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Kan gereelde ultraklankdiagnostiek skadelik wees?

Kan gereelde ultraklankdiagnostiek skadelik wees?


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Is daar enige kort- of langtermyn-effekte sigbaar in weefsels as 'n sone (of die hele) van die menslike liggaam dikwels met ultrasoniese golwe geskandeer word?


Ultraklank word beskou as 'n veilige prosedure (verwysing) wat ook deur die WGO aanvaar word (verwysing). Daar is egter studies wat die verband van ultraklankbehandeling met sommige ongewenste eienskappe toon.

Ultraklank kan moontlik gekoppel word aan 'n afname in liggaamsgewig by geboorte van babas (verwysing).

Gereelde gebruik van ultraklank kan babas beïnvloed wat geskandeer word om linkshandig groot te word (verwysing)

'n Beduidende migrasie van neurone (verandering van neurone vanaf hul regmatige area) is waargeneem by muise wat hulle aan ultraklank blootgestel het in die prenatale stadium. (verwysing).

'n Studie het gevind dat die brein van muise nadelig is tydens blootstelling aan ultraklank in die fetale stadium (verwysing).

So gebaseer op hierdie vraestelle, sou ek hulle nie 'n 100% veilig noem nie, maar hierdie toetse hou almal verband met herhaalde gebruik van ultraklankbeelding. Ultraklank gebruik spaarsamig en op geldige mediese aanduiding behoort nie 'n saak van kommer te wees nie.


Voordele en risiko's van ultraklank tydens swangerskap

Ultraklank is waarskynlik die mees algemene diagnostiese prosedure in verloskunde. Dit is gerieflik, pynloos, lewer onmiddellike, uitgebreide resultate, en word algemeen as veilig beskou. Sommige (maar nie alle) voordele wat in die literatuur beskryf word, is bekragtig deur bewysgebaseerde analise, soos swangerskapdatering. Ander word as klinies nuttig beskou, hoewel objektiewe bewyse minder sterk kan wees. Soos die geval is met byna enige mediese prosedure, hou die uitvoering daarvan egter sekere risiko's in: verkeerde diagnose aan die een kant en moontlike ongewenste effekte aan die ander kant. Die algemene opvatting bestaan ​​dat diagnostiese ultraklank (DUS) geen risiko vir die swanger pasiënt of haar fetus inhou nie. Nietemin is ultraklank 'n vorm van energie en demonstreer as sodanig effekte in biologiese weefsels wat dit deurkruis (bioeffekte). Die fisiese meganismes wat vir hierdie effekte verantwoordelik is, is termies of nie-termies (meganies). Dit is die rol van die wetenskap om te wys of enige van hierdie bio-effekte skadelik kan wees. ’n Risiko-voordeel-analise kan ook belangrik wees, asook opvoeding van die eindgebruikers om pasiënte se veiligheid te verseker.

Sleutelwoorde: Bioeffekte Fetus Meganiese effekte Swangerskap Risiko's Termiese effekte Ultraklank.


Ultraklankskanderings - rede tot kommer

Voorheen weergawes is gepubliseer in Mothering-tydskrif, uitgawe 102, Sept-Okt. 2000, en Nexus-tydskrif, vol 9, nr. 6, Okt-Nov. 2002.
'n Ten volle bygewerkte en uitgebreide weergawe word gepubliseer in Sagte geboorte, sagte moederskap: 'n Dokter se gids tot natuurlike bevalling en sagte vroeë ouerskapskeuses (Sarah J Buckley, Celestial Arts, 2009).

Toe ek in 1990 swanger was met my eerste baba, het ek besluit om nie 'n skandering te doen nie. Dit was 'n taamlik ongewone besluit, aangesien ek en my maat albei dokters is en selfs swangerskapskanderings self gedoen het - taamlik onbekwaam, maar soms nuttig - terwyl ek 'n paar jaar tevore in algemene verloskunde/huisdokter opgelei het.

Wat my die meeste beïnvloed het, was my gevoel dat ek iets belangriks as ma sou verloor as ek iemand toelaat om my baba te toets. Ek het geweet dat as 'n geringe of onsekere probleem opduik – en dit is nie ongewoon nie — dat ek verplig sou wees om weer en weer terug te keer, en dat dit na 'n rukkie sou voel asof my baba aan die stelsel behoort, en nie vir my nie.

In die jare sedertdien het ek nog drie ongeskandeerde babas gehad, en het baie artikels en navorsingsartikels oor ultraklank gelees. Niks wat ek gelees het, het my my besluit laat heroorweeg nie. Alhoewel ultraklank soms nuttig kan wees wanneer spesifieke probleme vermoed word, is my gevolgtrekking dat dit op sy beste ondoeltreffend en in erger geval gevaarlik is wanneer dit as 'n "siftingsinstrument" vir elke swanger vrou en haar baba gebruik word.
Ultraklank verlede en hede

Ultraklank is tydens die Tweede Wêreldoorlog ontwikkel om vyandelike duikbote op te spoor, en is daarna in die staalbedryf gebruik. In Julie 1955 het Ian Donald, Glasgow-chirurg, 'n industriële masjien geleen en, met behulp van beesvleis as kontrole, begin eksperimenteer met buikgewasse wat hy van sy pasiënte verwyder het. Hy het ontdek dat verskillende weefsels verskillende patrone van ultraklank-“eggo” gee, wat hom laat besef het dat ultraklank 'n revolusionêre manier bied om na die voorheen geheimsinnige wêreld van die groeiende baba te kyk.1

Hierdie nuwe tegnologie het vinnig na kliniese verloskunde versprei. Kommersiële masjiene het in 1963 beskikbaar geword 2 en teen die laat 1970's het ultraklank 'n roetine-deel van verloskundige sorg geword.3 Ultraklank word vandag as veilig en doeltreffend beskou en skandering het 'n oorgangsrite vir swanger vroue in ontwikkelde lande geword. Hier in Australië word beraam dat 99 persent van babas ten minste een keer in swangerskap geskandeer word – meestal as 'n roetine voorgeboortelike ultraklank (RPU) op 4 tot 5 maande. In die VSA, waar hierdie koste deur die versekeraar of privaat gedra word, het ongeveer 70 persent van swanger vroue 'n skandering.4

Daar is egter toenemende kommer oor die veiligheid en bruikbaarheid daarvan. Die Britse verbruikersaktivis Beverley Beech noem RPU "die grootste onbeheerde eksperiment in die geskiedenis",5 en die Cochrane Collaborative Database – die piek wetenskaplike gesag in medisyne - kom tot die gevolgtrekking dat,

… geen duidelike voordeel in terme van 'n substantiewe uitkomsmaatstaf soos perinatale mortaliteit [aantal babas wat sterf rondom die tyd van geboorte] kan nog gesien word as gevolg van die roetine-gebruik van ultraklank nie.6

Dit blyk 'n baie swak beloning vir die groot koste daaraan verbonde. In 1997-'8, byvoorbeeld, is $39 miljoen deur die Australiese federale regering vir swangerskapskanderings betaal - 'n enorme uitgawe vergeleke met $54 miljoen vir alle ander verloskundige mediese kostes.7 Hierdie syfer sluit nie die bykomende koste in wat die vrou self betaal het nie. In die VSA sal 'n geraamde US$1,2 miljard jaarliks ​​bestee word as elke swanger vrou 'n enkele roetine-skandering ondergaan.

In 1987 het die Britse radioloog H.D.Meire, wat al 20 jaar swangerskapskanderings gedoen het, gesê:

Die toevallige waarnemer kan dalk vergewe word dat hy wonder hoekom die mediese beroep nou betrokke is by die groothandelondersoek van swanger pasiënte met masjiene wat baie verskillende kragte uitstraal wat nie bewys is dat dit skadeloos is om inligting te bekom wat nie bewys is dat dit van enige kliniese waarde is nie. deur operateurs wat nie gesertifiseer is as bevoeg om die operasies uit te voer nie.8

Die situasie vandag is onveranderd, op elke punt.

Die verslag van die Senaatskomitee van 1999, 'Rocking the Cradle', het aanbeveel dat die koste-voordeel van roetine-skandering, en van huidige ultraklankpraktyke, formeel beoordeel word. Aanbevelings is ook gemaak om riglyne te ontwikkel vir die veilige gebruik van alle obstetriese ultraklank, asook vir die ontwikkeling van standaarde vir die opleiding van ultrasonograwe (sien hieronder). Tot dusver is nie een van hierdie aanbevelings geïmplementeer nie.7

Wat is ultraklank?

Die term "ultraklank" verwys na die ultrahoë frekwensie klankgolwe wat vir diagnostiese skandering gebruik word. Hierdie golwe beweeg teen 10 tot 20 miljoen siklusse per sekonde, vergeleke met 10 tot 20 duisend siklusse per sekonde vir hoorbare klank.2 Ultraklankgolwe word uitgestraal deur 'n transducer (die deel van die masjien wat op die liggaam geplaas word), en 'n prentjie van die onderliggende weefsels word opgebou uit die patroon van "eggo" golwe wat terugkeer. Harde oppervlaktes soos been sal 'n sterker eggo gee as sagte weefsel of vloeistowwe, wat die benige skelet 'n wit voorkoms op die skerm gee.

Gewone skanderings gebruik pulse van ultraklank wat slegs 'n breukdeel van 'n sekonde duur, met die interval tussen golwe wat deur die masjien gebruik word om die eggo wat terugkeer te interpreteer. Daarteenoor het Doppler-tegnieke, wat gebruik word in gespesialiseerde skanderings, fetale monitors en hand-held fetale stetoskope ("sonicids") deurlopende golwe, wat baie hoër vlakke van blootstelling gee as 'gepulste' ultraklank. Baie vroue besef nie dat die klein masjiene wat gebruik word om na hul baba se hartklop te luister, eintlik Doppler-ultraklank gebruik nie, alhoewel met redelike lae blootstellingsvlakke.

Meer onlangs het ultrasonograwe vaginale ultraklank gebruik, waar die transducer hoog in die vagina geplaas word, baie nader aan die ontwikkelende baba. Dit word meestal in vroeë swangerskap gebruik, wanneer abdominale skanderings swak beelde kan gee. Met vaginale ultraklank is daar egter min tussenliggende weefsel om die baba, wat in 'n kwesbare stadium van ontwikkeling is, te beskerm, en blootstellingsvlakke sal hoog wees. Om 'n vaginale ultraklank te hê is nie 'n aangename prosedure vir die vrou nie. Die term "diagnostiese verkragting" is geskep om te beskryf hoe sommige vroue vaginale skanderings ervaar.

Nog 'n onlangse toepassing vir ultraklank is die "nukale deurskynendheidstoets", waar die dikte van die velvou aan die agterkant van die baba se kop op ongeveer 3 maande gemeet word. 'n dik 'nukale (nek)vou' maak die baba statisties meer waarskynlik, Downs-sindroom te hê.

Wanneer die baba se risiko meer as een uit 250 geskat word, word 'n definitiewe toets aanbeveel. Dit behels die neem van van die baba se weefsel deur amniosentese of chorionvillus monsterneming. Ongeveer 19 uit 20 babas wat as 'hoërisiko' gediagnoseer word deur nekdeurskynendheid sal nie deur Downsindroom geraak word nie, en hul ma's sal etlike weke van onnodige angs ervaar het.

’n Nekdeurskynendheidsskandering bespeur nie alle babas wat deur Downsindroom geraak word nie. (Vir meer oor voorgeboortelike toetse, sien Sarah se artikel, oor voorgeboortelike diagnose, wat binnekort as e-boek en oudio-pakket verskyn.)

Inligting verkry uit ultraklank

Ultraklank word hoofsaaklik vir twee doeleindes tydens swangerskap gebruik - óf om 'n moontlike probleem op enige stadium van swangerskap te ondersoek, óf as 'n roetine-skandering op ongeveer 18 weke.

As daar byvoorbeeld bloeding in vroeë swangerskap is, kan ultraklank voorspel of miskraam onvermydelik is. Later in swangerskap kan ultraklank gebruik word wanneer 'n baba nie groei nie, of wanneer 'n stuitliggaam baba of tweeling vermoed word. In hierdie gevalle kan die inligting wat deur ultraklank verkry word, baie nuttig wees in besluitneming vir die vrou en haar versorgers. Die gebruik van roetine voorgeboortelike ultraklank (RPU) is egter meer omstrede, aangesien dit die skandering van alle swanger vroue behels in die hoop om die uitkoms vir sommige moeders en babas te verbeter.

Die tydsberekening van roetine-skanderings (18 tot 20 weke) word om pragmatiese redes gekies. Dit bied 'n redelik akkurate sperdatum — hoewel datering die akkuraatste is in die vroeë stadiums van swangerskap, wanneer babas die minste verskil in grootte — en die baba groot genoeg is om die meeste van die abnormaliteite te sien wat op ultraklank waarneembaar is. Op hierdie stadium is die EDD (verwagte afleweringsdatum) egter net tot 'n week weerskante akkuraat, en sommige studies het voorgestel dat 'n vroeë ondersoek, of berekeninge gebaseer op 'n vrou se menstruele siklus, so akkuraat soos RPU kan wees.9 10

En terwyl baie vroue gerusgestel word deur 'n normale skandering, bespeur RPU eintlik net tussen 17 en 85 persent van die 1 uit 50 babas wat groot abnormaliteite by geboorte het.11 12 'n Onlangse studie van Brisbane het getoon dat ultraklank by 'n groot vrouehospitaal ongeveer gemis het. 40 persent van abnormaliteite, met die meeste hiervan wat moeilik of onmoontlik is om op te spoor.13 Groot oorsake van intellektuele gestremdheid soos serebrale gestremdheid en Downsindroom sal waarskynlik nie op 'n roetine-skandering opgetel word nie, so ook hart- en nierabnormaliteite.

Wanneer 'n abnormaliteit opgespoor word, is daar 'n klein kans dat die bevinding 'n "vals positief" is, waar die ultraklankdiagnose verkeerd is. ’n Britse opname het getoon dat vir een uit 200 babas wat weens ernstige abnormaliteite geaborteer is, die diagnose op nadoodse ondersoek minder ernstig was as wat deur ultraklank voorspel is en die beëindiging was waarskynlik ongeregverdig. In hierdie opname het 2,4 persent van die babas wat met groot misvormings gediagnoseer is, maar nie geaborteer is nie, toestande gehad wat aansienlik oor- of ondergediagnoseer was.14

Daar is ook baie gevalle van foute met meer geringe abnormaliteite, wat angs en herhaalde skanderings kan veroorsaak, en daar is 'n paar toestande wat spontaan opgelos het.15

Sowel as vals positiewe, is daar ook onsekere gevalle, waar die ultraklankbevindinge nie maklik geïnterpreteer kan word nie, en die uitkoms vir die baba nie bekend is nie. In een studie wat vroue met 'n hoë risiko betrek het, was byna 10 persent van skanderings onseker.16 Dit kan geweldige angs vir die vrou en haar gesin skep, en die bekommernis word dalk nie besweer deur die geboorte van 'n normale baba nie. In dieselfde studie het moeders met “twyfelagtige” diagnoses drie maande ná die geboorte van hul baba steeds hierdie angs gehad.

In sommige gevalle van onsekerheid kan die twyfel opgelos word deur verdere toetse soos amniosentese. In hierdie situasie kan daar tot twee weke wag vir resultate, waartydens 'n ma moet besluit of sy die swangerskap sal beëindig as 'n abnormaliteit gevind word. Selfs ma's wat gerusstellende nuus ontvang, het gevoel dat hierdie proses inmeng met hul verhouding met hul baba.17

Behalwe om die EDD te skat en na te gaan vir groot abnormaliteite, kan RPU ook 'n laagliggende plasenta (plasenta praevia) identifiseer en die teenwoordigheid van meer as een baba in 'n vroeë stadium van swangerskap opspoor. 19 uit 20 vroue wat plasenta praevia op 'n vroeë skandering opgespoor het, sal egter onnodig bekommerd wees: die plasenta sal effektief opbeweeg, en nie probleme by die geboorte veroorsaak nie. Verder is die opsporing van plasenta praevia deur RPU nie gevind as veiliger as opsporing in kraam nie.15 Geen verbetering in uitkoms is getoon vir meervoudige swangerskappe nie, of die oorgrote meerderheid hiervan sal voor kraam opgespoor word, selfs sonder RPU.

Die American College of Obstetricians, in hul 1997-riglyne oor roetine-ultraklank in laerisiko-swangerskap, kom tot die gevolgtrekking

In 'n populasie van vroue met 'n lae-risiko swangerskappe, kan nie 'n vermindering in perinatale morbiditeit [skade aan babas rondom die tyd van geboorte] en mortaliteit of 'n laer koers van onnodige intervensies van roetine diagnostiese ultraklank verwag word nie. Dus moet ultraklank uitgevoer word vir spesifieke aanduidings in laerisiko swangerskap.18

Biologiese effekte van ultraklank

Dit is bekend dat ultraklankgolwe weefsels op twee hoofmaniere beïnvloed. Eerstens veroorsaak die sonarstraal verhitting van die gemerkte area met ongeveer een graad celsius. Dit word veronderstel om nie-beduidend te wees nie, gebaseer op die hele liggaam verhitting tydens swangerskap, wat blyk te wees veilig tot 2,5 grade Celsius.19

Die tweede erkende effek is kavitasie, waar die klein sakke gas wat in soogdierweefsel bestaan, vibreer en dan ineenstort. In hierdie situasie

… temperature van baie duisende grade celsius in die gas skep 'n wye reeks chemiese produkte, waarvan sommige potensieel giftig is. Hierdie gewelddadige prosesse kan geproduseer word deur mikro-sekonde-pulse van die soort wat in mediese diagnose gebruik word...19

Die betekenis van kavitasie-effekte in menslike weefsel is onbekend.

'n Aantal studies het voorgestel dat hierdie effekte werklik kommerwekkend is in lewende weefsels. Die eerste studie wat probleme voorstel, was 'n studie oor selle wat in die laboratorium gekweek is. Daar is gesien dat selafwykings wat veroorsaak word deur blootstelling aan ultraklank vir verskeie generasies voortduur.20 Ageen studie het getoon dat, by pasgebore rotte, (wat in 'n soortgelyke stadium van breinontwikkeling as mense is op vier tot vyf maande in utero), ultraklank die miëlien wat senuwees bedek, kan beskadig,21 wat aandui dat die senuweestelsel veral vatbaar kan wees vir skade deur hierdie tegnologie.

Brennan en kollegas, het berig dat die blootstelling van muise aan dosisse tipies van obstetriese ultraklank 'n 22 persent vermindering in die tempo van seldeling, en 'n verdubbeling van die tempo van aptose, of geprogrammeerde seldood, in die selle van die dunderm veroorsaak.22

Mol kommentaar

As blootstelling aan ultraklank ... die dood van selle veroorsaak, dan sal die praktyk van ultrasoniese beelding op 16 tot 18 weke verlies van neurone [breinselle] veroorsaak met min vooruitsig op vervanging van verlore selle ... Die kwesbaarheid is nie vir misvorming nie, maar vir wanontwikkeling wat lei tot verstandelike gestremdheid veroorsaak deur algehele vermindering in die aantal funksionerende neurone in die toekomstige serebrale hemisfere.23

Studies op mense wat aan ultraklank blootgestel is, het getoon dat moontlike nadelige effekte voortydige ovulasie, 24 premature kraam of miskraam, 15 25 lae geboortegewig, 26 27 swakker toestand by geboorte, 28 29 perinatale dood, 28-30 disleksie, 31 vertraagde spraakontwikkeling, insluit, 32 en minder regshandigheid.33-36 Nie-regshandigheid word, in ander omstandighede, gesien as 'n merker van skade aan die ontwikkelende brein.35 37 Een Australiese studie het getoon dat babas wat aan 5 of meer doppler-ultraklanke blootgestel is, 30% meer was sal waarskynlik intrauteriene groeivertraging (IUGR) ontwikkel - 'n toestand wat ultraklank dikwels gebruik word om op te spoor.26

Twee langtermyn gerandomiseerde gekontroleerde proewe, wat blootgestelde en onblootgestelde kinders se ontwikkeling op agt tot nege jaar oud vergelyk het, het geen meetbare effek van ultraklank gevind nie.38 39 Soos die skrywers egter opmerk, is intensiteite wat vandag gebruik word baie keer hoër as in 1979 tot 1981 Verder, in die hooftak van een proef, was skanderingstyd slegs drie minute.40 Meer studies is uiteraard nodig in hierdie area, veral in die gebiede van Doppler en vaginale ultraklank, waar blootstellingsvlakke baie hoër is.

'n Verdere probleem met die bestudering van die effek van ultraklank is die groot verskeidenheid uitset, of dosis, moontlik vanaf 'n enkele masjien. Moderne masjiene kan vergelykbare ultraklankfoto's gee met 'n laer, of 'n 5 000 keer hoër dosis,8 en daar is geen standaarde om te verseker dat die laagste dosis gebruik word nie. As gevolg van die kompleksiteit van masjiene, is dit moeilik om selfs die dosis wat in elke ondersoek gegee word te kwantifiseer.41 In Australië is opleiding vrywillig, selfs vir verloskundiges, en die vaardigheid en ervaring van operateurs verskil baie.

'n Opsomming van die veiligheid van ultraklank in menslike studies, gepubliseer in Mei 2002 in die gesogte Amerikaanse joernaal Epidemiology

…daar kan 'n verband wees tussen voorgeboortelike ultraklankblootstelling en nadelige uitkoms. Sommige van die gerapporteerde effekte sluit in groeibeperking, vertraagde spraak, disleksie en nie-regshandigheid wat verband hou met ultraklankblootstelling. Voortgesette navorsing is nodig om die potensiële nadelige gevolge van ultraklankblootstelling tydens swangerskap te evalueer. Hierdie studies moet die akoestiese uitset, blootstellingstyd, aantal blootstellings per proefpersoon, en die tydsberekening tydens die swangerskap wanneer blootstelling(s) plaasgevind het, meet.42

Vroue se ervarings van ultraklank

Vroue is in geen stadium in die ontwikkeling van hierdie tegnologie geraadpleeg nie, en hul ervarings en wense word veronderstel om saam te val met, of minder belangrik te wees as, die mediese inligting wat ultraklank verskaf. Ondersteuners van RPU veronderstel byvoorbeeld dat vroeë diagnose en/of beëindiging voordelig is vir die geaffekteerde vrou en haar gesin. Die ontdekking van 'n groot abnormaliteit op RPU kan egter tot baie moeilike besluitneming lei.

Sommige vroue wat instem om 'n ultraklank te kry, is onbewus daarvan dat hulle inligting oor hul baba kan kry wat hulle nie wil hê nie, aangesien hulle nie 'n beëindiging sal oorweeg nie. Ander vroue kan onder druk voel om 'n beëindiging te hê, of ten minste 'n mate van emosionele distansie van hul "abnormale" baba voel.17 Verder is daar geen bewyse dat vroue wat beëindiging gekies het, op die lang termyn sielkundig beter daaraan toe is as vroue wie se babas in werklikheid by geboorte gesterf het, is daar voorstelle dat die teenoorgestelde in sommige gevalle waar kan wees.43 En wanneer beëindiging gekies is, is dit onwaarskynlik dat vroue hul storie met ander sal deel en kan hulle aansienlike skuld en pyn ervaar uit die wete dat hulle het self die verlies gekies.

Wanneer geringe abnormaliteite gevind word - wat moontlik by geboorte teenwoordig is of nie, soos hierbo bespreek - kan vroue voel dat sommige van die plesier van hul swangerskap weggeneem is.

Vroue se ervarings met ultraklank en ander toetse wat vir voorgeboortelike diagnose gebruik word (bv. amniosentese) word deurdagte weergegee in die boek The Tentative Pregnancy deur Barbara Katz Rothman.44 Die skrywer dokumenteer die hartseer waardeur vroue kan gaan wanneer 'n moeilike diagnose gemaak word - vir sommige vroue , kan hierdie pyn jare neem om op te los. Sy stel voor dat die groot aantal siftingstoetse wat tans aangebied word om na abnormaliteite te kyk, elke vrou kan laat voel dat haar swangerskap ‘voorlopig’ is totdat sy gerusstellende resultate kry.

Na my mening verteenwoordig ultraklank ook nog 'n manier waarop die diep interne kennis wat 'n ma het van haar liggaam en haar baba sekondêr gemaak word tot tegnologiese inligting wat van 'n 'kundige' afkomstig is wat 'n masjien gebruik. So word die 'kultus van die deskundige' vanaf die vroegste lewensweke ingeprent.

Verder deur die baba as 'n aparte wese te behandel, skei ultraklank ma kunsmatig van baba lank voordat dit 'n fisiologiese of psigiese werklikheid is. Dit beklemtoon verder ons kulture wat individualisme bo wedersyds bevoordeel en skep die toneel vir moontlike maar na my mening kunsmatige belangebotsings tussen ma en baba tydens swangerskap, geboorte en ouerskap.

Gevolgtrekkings en aanbevelings

Ek wil alle swanger vroue aanmoedig om diep te dink voordat hulle kies om 'n roetine-ultraklank te hê. Dit is nie verpligtend nie, ten spyte van wat sommige dokters gesê het, en die risiko's, voordele en implikasies van skandering moet vir elke ma en baba oorweeg word, volgens hul spesifieke situasie.

As jy kies om 'n skandering te hê, wees duidelik oor die inligting wat jy doen en nie wil hê dat dit vertel word nie. Laat jou skandering deur 'n operateur met 'n hoë vlak van vaardigheid en ervaring doen (gewoonlik beteken dit om ten minste 750 skanderings per jaar uit te voer) en sê dat jy die kortste moontlike skandering wil hê. Vra hulle om die vorm in te vul, of vir jou die inligting te gee, soos hierbo, en dit te onderteken.

Indien 'n abnormaliteit gevind word, vra vir berading en 'n tweede opinie so gou as prakties. En onthou dat dit jou baba, jou liggaam en jou keuse is.

Vir die hele storie oor swangerskap-ultraklank, sien dr Buckley se webinar "Swangerskap-ultraklank", insluitend 'n 2016-opdatering van hierdie hoofstuk. Beskikbaar vir GentleNaturalBirth professionele lede. Sien alle GNB professionele webinars hier.

Verwysings

1. Wagner M. Ultraklank: meer skade as goed? Verloskunde Vandag Int Vroedvrou 1999(50):28-30.

2. de Crespigny L, Dredge R. Watter toetse vir my ongebore baba?- Ultraklank en ander voorgeboortelike toetse. 2de uitg. Melbourne: Oxford University Press, 1996.

3. Oakley A. Die geskiedenis van ultraklank in verloskunde. Geboorte 198613(1):8-13.

4. Martin J, et al. Geboortes: Finale data vir 2002. Nasionale belangrike statistiekverslae. Hyattsville MD: Nasionale Sentrum vir Gesondheidstatistiek, 2003.

5. Beuk BL. Ultraklank ongeldig? Praat by Mercy-hospitaal, Melbourne, April 1993.

6. Neilson JP. Ultraklank vir fetale assessering in vroeë swangerskap. Cochrane Database Syst Rev 2000(2):CD000182.

7. Senaat Gemeenskapsake Verwysingsgroep. Rocking the Cradle 'n Verslag oor bevallingprosedures. Canberra: Statebond van Australië, 1999.

8. Meire HB. Die veiligheid van diagnostiese ultraklank. Br J Obstet Gynaecol 198794(12):1121-2.

9. Olsen O, Aaroe Clausen J. Roetine-ultraklankdatering is nie meer akkuraat as die kalendermetode getoon nie. Br J Obstet Gynaecol 1997104(11):1221-2.

10. Kieler H, et al. Vergelyking van ultrasoniese meting van bipariëtale deursnee en laaste menstruasieperiode as 'n voorspeller van dag van aflewering by vroue met gereelde 28-dae-siklusse. Acta Obstet Gynecol Scand 199372(5):347-9.

11. Ewigman BG, et al. Effek van prenatale ultraklank sifting op perinatale uitkoms. RADIUS Studiegroep. N Engl J Med 1993329(12):821-7.

12. Geluk CA. Waarde van roetine-ultraklankskandering op 19 weke: 'n vier jaar studie van 8849 aflewerings. Br Med J 1992304(6840):1474-8.

13. Chan F. Beperkings van Ultraklank. Perinatale Vereniging van Australië en Nieu-Seeland 1ste jaarlikse kongres. Freemantle, Australië, 1997.

14. Brand IR, et al. Spesifisiteit van voorgeboortelike ultraklank in die Yorkshire-streek: 'n voornemende studie van 2261 ultraklankbespeurde anomalieë ACOG-komitee-opinie. Nommer 297, Augustus 2004. Nie-mediese gebruik van obstetriese ultraklank. Br J Obstet Gynaecol 1994101(5):392-7.

15. Saari-Kemppainen A, et al. Ultraklank sifting en perinatale mortaliteit: beheerde proef van sistematiese een-stadium sifting tydens swangerskap. Die Helsinki-ultraklankproef. Lancet 1990336(8712):387-91.

16. Sparling JW, et al. Die verhouding van obstetriese ultraklank tot ouer- en babagedrag. Obstet Gynecol 198872(6):902-7.

17. Brookes A. Women’s ervaring van roetine prenatale ultraklank. Healthsharing Women: The Newsletter of Healthsharing Women’s Health Resource Service, melbourne 1994/55(3-4):1-5.

18. Amerikaanse Kollege van Verloskundiges en Ginekoloë. ACOG oefen patrone. Roetine-ultraklank in laerisiko swangerskap. Nommer 5, Augustus 1997. Int J Gynaecol Obstet 199759(3):273-8.

19. American Institute of Ultrasound in Medicine Bioeffects Committee. Bioeffekte-oorwegings vir die veiligheid van diagnostiese ultraklank. J Ultraklank Med 19887(9 Suppl):S1-38.

20. Liebeskind D, et al. Diagnostiese ultraklank: effekte op die DNA en groeipatrone van dierselle. Radiologie 1979131(1):177-84.

21. Ellisman MH, et al. Diagnostiese vlakke van ultraklank kan miëlinasie ontwrig. Exp Neurol 198798(1):78-92.

22. Stanton MT, et al. Diagnostiese ultraklank veroorsaak verandering binne getalle van kriptale mitotiese en apoptotiese selle in dunderm. Life Sci 200168(13):1471-5.

23. Mole R. Moontlike gevare van beelding en Doppler ultraklank in verloskunde. Geboorte 198613 Suppl:23-33 Suppl, p 26.

24. Testart J, et al. Voortydige ovulasie na ovariale ultraklank. Br J Obstet Gynaecol 198289(9):694-700.

25. Lorenz RP, et al. Gerandomiseerde voornemende proef wat ultraklank en bekkenondersoek vir premature kraamtoesig vergelyk. Am J Obstet Gynecol 1990162(6):1603-7 bespreking 1607-10.

26. Newnham JP, et al. Effekte van gereelde ultraklank tydens swangerskap: 'n gerandomiseerde beheerde proef. Lancet 1993342(8876):887-91.

27. Geerts LT, et al. Roetine-obstetriese ultraklankondersoeke in Suid-Afrika: koste en effek op perinatale uitkoms–a voornemende gerandomiseerde beheerde proef. Br J Obstet Gynaecol 1996103(6):501-7.

28. Newnham JP, et al. Dopplervloeisnelheidsgolfvormanalise in hoërisiko-swangerskappe: 'n gerandomiseerde beheerde proef. Br J Obstet Gynaecol 199198(10):956-63.

29. Thacker SB. Kwaliteit van beheerde kliniese proewe. Die geval van beeldende ultraklank in verloskunde: 'n oorsig. Br J Obstet Gynaecol 198592(5):437-44.

30. Davies JA, et al. Gerandomiseerde beheerde proef van Doppler ultraklank sifting van plasentale perfusie tydens swangerskap. Lancet 1992340(8831):1299-303.

31. Stark CR, et al. Kort- en langtermynrisiko's na blootstelling aan diagnostiese ultraklank in utero. Obstet Gynecol 198463(2):194-200.

32. Campbell JD, et al. Gevalle-kontrole studie van prenatale ultraklankblootstelling by kinders met vertraagde spraak. Can Med Assoc J 1993149(10):1435-40.

33. Salvesen KA, et al. Roetine ultraklank in utero en daaropvolgende handigheid en neurologiese ontwikkeling. Br Med J 1993307(6897):159-64.

34. Salvesen KA, Eik-Nes SH. Ultraklank tydens swangerskap en daaropvolgende kinderjare nie-regshandigheid: 'n meta-analise. Ultraklank Obstet Gynecol 199913(4):241-6.

35. Kieler H, et al. Sinistraliteit–a newe-effek van prenatale sonografie: 'n vergelykende studie van jong mans. Epidemiologie 200112(6):618-23.

36. Kieler H, et al. Roetine ultraklank sifting in swangerskap en die kinders se daaropvolgende handigheid. Early Hum Dev 199850(2):233-45.

37. Odent M. Waar kom handigheid vandaan? Handigheid vanuit 'n oergesondheidsnavorsingsperspektief. Primal Health Research 19986(1):1-6.

38. Kieler H, et al. Roetine ultraklank sifting in swangerskap en die kinders se daaropvolgende neurologiese ontwikkeling. Obstet Gynecol 199891(5 Pt 1):750-6.

39. Salvesen KA, et al. Roetine ultraklank in utero en skoolprestasie op ouderdom 8-9 jaar. Lancet 1992339(8785):85-9.

40. Salvesen KA, et al. Roetine-ultrasonografie in utero en daaropvolgende groei tydens die kinderjare. Ultraklank Obstet Gynecol 19933(1):6-10.

41. Taylor KJ. 'n Versigtige benadering tot ultraklankbeelding van die fetus en pasgebore baba. Geboorte 199017(4):218-21, 223 bespreking 221-2.

42. Marinac-Dabic D, et al. Die veiligheid van prenatale ultraklankblootstelling in menslike studies. Epidemiologie 200213(3 Suppl):S19-22.

43. Watkins D. 'n Alternatief vir beëindiging van swangerskap. Praktisyn 1989233(1472):990, 992.

44. Rothman B. Die voorlopige swangerskap. Amniosentese en die seksuele politiek van moederskap. 2de uitg. Londen: Pandora, 1994.


Fetale termiese effekte van diagnostiese ultraklank

Sentrum vir Biomediese Fisika, Temple University Medical School, Philadelphia, Pennsylvania.

Ontvang 12 April 2007 van die Departement Verloskunde en Ginekologie, Rush Universiteit, Chicago, Illinois, VSA

Fakulteit Gesondheidswetenskappe, Universiteit van Sydney, Sydney, Nieu-Suid-Wallis, Australië

Bath Universiteit en Royal United Hospitaal, Bath, Engeland

SRI International, Molekulêre Fisika Laboratoria, Menlo Park, Kalifornië, VSA

Departement Radiologie, Harvard Mediese Skool, Boston, Massachusetts, VSA

Sentrum vir Biomediese Fisika, Temple University Medical School, Philadelphia, Pennsylvania.

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Abstrak

Prosesse wat 'n biologiese effek kan produseer met 'n mate van verhitting (dws ongeveer 1°C bo die fisiologiese temperatuur) werk via 'n termiese meganisme. Ondersoeke met laboratoriumdiere het gedokumenteer dat gepulseerde ultraklank verhogings van temperatuur en skade in biologiese weefsels in vivo kan veroorsaak, veral in die teenwoordigheid van been (intrakraniale temperatuurverhoging). Akoestiese uitsette wat gebruik word om hierdie nadelige bio-effekte te veroorsaak, is binne die diagnostiese omvang, hoewel blootstellingstye gewoonlik aansienlik langer is as in kliniese praktyk. Toestande teenwoordig tydens vroeë swangerskap, soos 'n gebrek aan perfusie, kan bio-effekte bevoordeel. Termies-geïnduseerde teratogenese is in baie dierestudies getoon, sowel as verskeie gekontroleerde menslike studies, maar menslike studies het nie 'n oorsaaklike verband tussen diagnostiese ultraklankblootstelling tydens swangerskap en nadelige biologiese effekte op die fetus getoon nie. Alle menslike epidemiologiese studies is egter uitgevoer met kommersieel beskikbare toestelle wat voor 1992 gedateer het, dit wil sê met akoestiese uitsette wat nie 'n ruimtelike-piek tydelike-gemiddelde intensiteit van 94 mW/cm 2 oorskry nie. Huidige limiete in die Verenigde State laat 'n ruimtelike-piek tydelike-gemiddelde intensiteit van 720 mW/cm 2 vir fetale toedienings toe. Die sinergistiese effek van 'n verhoogde liggaamstemperatuur (koorsstatus) en ultraklankinsonasie is nie in diepte ondersoek nie. Beskikbare bewyse, eksperimenteel of epidemiologies, is onvoldoende om tot die gevolgtrekking te kom dat daar 'n oorsaaklike verband is tussen obstetriese diagnostiese ultraklankblootstelling en ooglopende nadelige termiese effekte op die fetus. Baie subtiele effekte kan egter nie uitgesluit word nie en dui op 'n behoefte aan verdere navorsing, hoewel navorsing by mense uiters moeilik kan wees om te realiseer.

This article analyzes thermal effects of fetal ultrasound exposure. The normal core human body temperature is generally accepted to be 37°C with a diurnal variation of ±0.5°C to 1°C, 1 , 2 although 36.8°C ± 0.4°C (95% confidence interval) may be closer to the actual mean for large populations. 3 During the entire gestation, the temperature of the human embryo/fetus is higher than the maternal core body temperature 4 and gradually rises until, in the final trimester (near term), it exceeds that of the mother by 0.5°C. 5 Thermally induced teratogenesis has been shown in many animal studies, as well as several controlled human studies. 6 Edwards 7 and others have shown that hyperthermia is teratogenic for numerous animal species, including the human, and suggested a 1.5°C temperature elevation above the normal value as a universal threshold. 8 An elevated maternal temperature in early gestation has been associated with an increased incidence of congenital anomalies. 9 Tolerance to increased temperature (thermotolerance) is an important aspect of thermal teratogenesis. Thermotolerance is induced by the production of heat shock proteins (HSPs), which occurs (up to a limit) during a relatively slow (10- to 15-minute) temperature increase of the whole body. 10 Diagnostic ultrasound exposures of mammalian embryos or fetuses in vivo and in vitro do not cause a whole-body temperature increase in the mother but can potentially do so in the embryo. In principle, heating with ultrasound could occur so rapidly that the protective effects of HSPs might not come into play. There are data on effects of hyperthermia and measurements of in vivo temperature induced by pulsed ultrasound but not in the human. 11 – 14 These data have been widely reviewed. 15 – 20 However, there is a serious lack of data on the effects of ultrasound while rigorously excluding other confounding factors. A number of epidemiologic studies of possible developmental effects of obstetric ultrasound were performed before 1992, when exposures of the fetus, if anything, were lower on average than they are today. The results overall were negative. Around 1992, the maximum permitted acoustic output of clinical ultrasound instruments operating in the obstetric mode was allowed to increase by a factor of almost 8. 21 Potentially of even greater significance, no report clearly defines the duration of actual exposure. Epidemiology, of course, cannot be expected to reveal subtle effects. Today, ultrasound is so much a part of obstetric care that it would be very difficult to design an ethically acceptable epidemiologic study.

The material in this article will be presented in the following manner: “Definitions,” “Mechanisms of Tissue Heating,” “Measured Temperature Rise in Human Fetal Tissue,” “Intracranial Temperature Elevation,” “Epidemiologic Data,” “Clinical Studies,” “Discussion Regarding Obstetric Issues in the Human,” and “Conclusions and Recommendations.”


Ultrasound: More Harm than Good?

The ultrasound story begins in July 1955 when an obstetrician in Scotland, Ian Donald, borrowed an industrial ultrasound machine used to detect flaws in metal and tried it out on some tumours, which he had removed previously, using a beefsteak as the control. He discovered that different tumours produced different echoes. Soon Donald was using ultrasound not only for abdominal tumours in women but also on pregnant women. Articles surfaced in the medical journals, and its use quickly spread throughout the world.

The dissemination of ultrasound into clinical obstetrics is reflected in inappropriate statements made in the obstetrical literature regarding its appropriate use: “One of the lessons of history is, of course, that it repeats itself. The development of obstetric ultrasound thus mirrors the application to human pregnancy of diagnostic X-rays. Both, within a few years of discovery, were being used to diagnose pregnancy and to measure the growth and normality of the fetus. In 1935 it was said that “antenatal work without the routine use of X-rays is no more justifiable than would be the treatment of fractures“ (Reece, 1935: 489). In 1978: “It can be stated without qualification that modern obstetrics and gynecology cannot be practiced without the use of diagnostic ultrasound“ (Hassani, 1978). Two years later, it was said that “ultrasound is now no longer a diagnostic test applied to a few pregnancies regarded on clinical grounds as being at risk. It can now be used to screen all pregnancies and should be regarded as an integral part of antenatal care“ (Campbell & Little, 1980). On neither of these dates did evidence qualify the speakers to make these assertions.

It is not only doctors who have tried to promote ultrasound with statements that go beyond the scientific data. Commercial interests also have been actively promoting ultrasound, and not only to doctors and hospitals. As an example, an advertisement in a widely read Sunday newspaper (The Times, London) claimed: Toshiba decided to design a diagnostic piece of equipment that would be absolutely safe … .The name: Ultrasound. A consumer organization in Britain complained to the Advertising Standards Authority that Toshiba was making an untrue claim, and the complaint was upheld. In many countries, the commercial application of ultrasound scanning during pregnancy is widespread, offering “baby look“ and “fun ultrasound“ in order to “meet your baby“ with photographs and home videos.

The extent to which medical practitioners nevertheless followed such scientifically unjustified advice, and the degree to which this technology proliferated, can be illustrated by recent data from three countries. In France, in one year three million ultrasound examinations were done on 700,000 pregnant women-an average of more than four scans per pregnancy.

These examinations cost French taxpayers more than all other therapeutic and diagnostic procedures done on these pregnant women. In Australia, where the health service pays for four routine scans, in one recent year billing for obstetrical ultrasound was $60 million in Australian dollars. A 1993 editorial in U.S.A. Today makes the following statement: “Baby’s first picture-a $200 sonogram shot in the womb-is a nice addition to any family album. But are sonograms medically worth $1 billion of the nation’s scarce health-care dollars? That’s the question raised by a United States study released this week. It found the sonograms that doctors routinely perform on healthy pregnant women don’t make any difference to the health of their babies.“

After a technology has spread widely in clinical practice, the next step is for health policymakers to accept it as standard care financed by the official health sector.

Several European countries now have official policy for one or more routine ultrasound scans during pregnancy. For example, in 1980 the Maternity Care Guidelines in West Germany stated the right of each pregnant woman to be offered at least two ultrasound scans during pregnancy. Austria quickly followed suit, approving two routine scans. Do the scientific data justify such widespread use and great cost of ultrasound scanning?

When Is Ultrasound Helpful?

In assessing the effectiveness of ultrasound in pregnancy, it is essential to make the distinction between its selective use for specific indications and its routine use as a screening procedure.

Essentially, ultrasound has proven valuable in a handful of specific situations in which the diagnosis “remains uncertain after clinical history has been ascertained and a physical examination has been performed.“ Yet, considering whether the benefits outweigh the costs of using ultrasound routinely, systematic medical research has not supported routine use.

One of the most common justifications given today for routine ultrasound scanning is to detect intrauterine growth retardation (IUGR). Many clinicians insist that ultrasound is the best method for the identification of this condition. In 1986, a professional review of 83 scientific articles on ultrasound showed that “for intrauterine growth retardation detection, ultrasound should be performed only in a high-risk population.“ In other words, the hands of an experienced midwife or doctor feeling a pregnant woman’s abdomen are as accurate as the ultrasound machine for detecting IUGR. The same conclusion was reached by a study in Sweden comparing repeated measurement of the size of the uterus by a midwife with repeated ultrasonic measurements of the head size of the fetus in 581 pregnancies. The report concludes: “Measurements of uterus size are more effective than ultrasonic measurements for the antenatal diagnosis of intrauterine growth retardation.“

If doctors continue to try to detect IUGR with ultrasound, the result will be high false-positive rates. Studies show that even under ideal conditions, such as do not exist in most settings, it is likely that over half of the time a positive IUGR screening test using ultrasound is returned, the test is false, and the pregnancy is in fact normal. The implications of this are great for producing anxiety in the woman and the likelihood of further unnecessary interventions.

There is another problem in screening for IUGR. One of the basic principles of screening is to screen only for conditions for which you can do something. At present, there is no treatment for IUGR, no way to slow up or stop the process of too-slow growth of the fetus and return it to normal. So it is hard to see how screening for IUGR could be expected to improve pregnancy outcome.

We are left with the conclusion that, with IUGR, we can only prevent a small amount of it using social interventions (nutrition and substance abuse programs), are very inaccurate at diagnosing it, and have no treatment for it. If this is the present state of the art, there is no justification for clinicians using routine ultrasound during pregnancy for the management of IUGR. Its use should be limited to research on IUGR.

Once again it is interesting to look at what happened with the issue of safety of X-rays during pregnancy. X-rays were used on pregnant women for almost fifty years and assumed to be safe. In 1937, a standard textbook on antenatal care stated: “It has been frequently asked whether there is any danger to the life of the child by the passage of X- rays through it it can be said at once there is none if the examination is carried out by a competent radiologist or radiographer.“ A later edition of the same textbook stated: “It is now known that the unrestricted use of X-rays through the fetus caused childhood cancer.“ This story illustrates the danger of assuming safety. In this regard, a statement from a 1978 textbook is relevant: “One of the great virtues of diagnostic ultrasound has been its apparent safety. At present energy levels, diagnostic ultrasound appears to be without injurious effect … all the available evidence suggests that it is a very safe modality.“

That ultrasound during pregnancy cannot be simply assumed to be harmless is suggested by good scientific work in Norway. By following up on children at age eight or nine born of mothers who had taken part in two controlled trials of routine ultrasound in pregnancy, they were able to show that routine ultrasonography was associated with a symptom of possible neurological problems.

With regard to the active scientific pursuit of safety, an editorial in Lancet, a British medical journal, says: “There have been no randomized controlled trials of adequate size to assess whether there are adverse effects on growth and development of children exposed in utero to ultrasound. Indeed, the necessary studies to ascertain safety may never be done, because of lack of interest in such research.“

The safety issue is made more complicated by the problem of exposure conditions. Clearly, any bio-effects that might occur as a result of ultrasound would depend on the dose of ultrasound received by the fetus or woman. But there are no national or international standards for the output characteristics of ultrasound equipment. The result is the shocking situation described in a commentary in the British Journal of Obstetrics and Gynaecology, in which ultrasound machines in use on pregnant women range in output power from extremely high to extremely low, all with equal effect. The commentary reads, “If the machines with the lowest powers have been shown to be diagnostically adequate, how can one possibly justify exposing the patient to a dose 5,000 times greater?“ It goes on to urge government guidelines on the output of ultrasound equipment and for legislation making it mandatory for equipment manufacturers to state the output characteristics. As far as is known, this has not yet been done in any country.

Safety is also clearly related to the skill of the ultrasound operator. At present, there is no known training or certification for medical users of ultrasound apparatus in any country. In other words, the birth machine has no license test for its drivers.

Looking Ahead: Ultrasound and the Future

Although ultrasound is expensive, routine scanning is of doubtful usefulness, and the procedure has not yet been proved to be safe, this technology is widely used, and its use is increasing rapidly without control. Nevertheless, health policy is slow to develop. No country is known to have developed policies with regard to standards for the machines, nor for the training and certification of the operators. A few industrialized countries have begun to respond to the data showing lack of effectiveness for routine scanning of all pregnant women. In the United States, for example, a consensus conference on diagnostic ultrasound imaging in pregnancy concluded that “the data on clinical effectiveness and safety do not allow recommendation for routine screening at this time there is a need for multidisciplinary randomized controlled clinical trials for an adequate assessment.“

Denmark, Sweden, and the United Kingdom have made similar statements against routine screening. The World Health Organisation (WHO), in an attempt to stimulate governments to develop policy on this issue, published the following statement:

“The World Health Organisation stresses that health technologies should be thoroughly evaluated prior to their widespread use. Ultrasound screening during pregnancy is now in widespread use without sufficient evaluation. Research has demonstrated its effectiveness for certain complications of pregnancy, but the published material does not justify the routine use of ultrasound in pregnant women. There is also insufficient information with regard to the safety of ultrasound use during pregnancy. There is as yet no comprehensive, multidisciplinary assessment of ultrasound use during pregnancy, including: clinical effectiveness, psychosocial effects, ethical considerations, legal implications, cost benefit, and safety.

“WHO strongly endorses the principle of informed choice with regard to technology use. The health-care providers have the moral responsibility: fully to inform the public about what is known and not known about ultrasound scanning during pregnancy and fully to inform each woman prior to an ultrasound examination as to the clinical indication for ultrasound, its hoped-for benefit, its potential risk, and alternative available, if any.“

This statement, sadly, is as relevant today. During the 1980s and early 1990s, a number of us were raising questions about both the effectiveness and safety of fetal scanning. Our voice of caution, however, was like a cry in the wilderness as the technology proliferated.

Then, during the course of one month in late 1993, two landmark scientific papers were published. The first paper, a largely randomized trial of the effectiveness of routine prenatal ultrasound screening, studied the outcome of more than 15,000 pregnant women who either received two routine scans at 15 to 22 weeks and 31 to 35 weeks, or were scanned only for medical indications.

Results showed that the mean number of sonograms in the ultrasound group was 2.2 and in the control group (for indication only) was 0.6. The rate of adverse outcome (fetal death, neonatal death, neonatal morbidity), as well as the rate of preterm delivery and distribution of birth weights, was the same for both groups. In addition, in the author’s words: “The ultrasonic detection of congenital abnormalities has no effect on perinatal outcome.“ At last we have a randomized clinical trial of sufficient size to conclude that there is no value to routine scanning during pregnancy.

The second landmark paper, also a randomized controlled trial, looked at the safety of repeated prenatal ultrasound imaging. While the original purpose of the trial was hopefully to demonstrate the safety of repeated scanning, the results were the opposite. From 2,834 pregnant women, 1,415 received ultrasound imaging at 18, 24, 28, 34 and 38 weeks gestation (intensive group) while the other 1,419 received single ultrasound imaging at 18 weeks (regular group). The only difference between the two groups was significantly higher (one-third more) intrauterine growth retardation in the intensive group. This important and serious finding prompted the authors to state: “It would seem prudent to limit ultrasound examinations of the fetus to those cases in which the information is likely to be of clinical importance.“ Ironically, it is now likely that ultrasound may lead to the very condition, IUGR, that it has for so long claimed to be effective in detecting.

Although we now have sufficient scientific data to be able to say that routine prenatal ultrasound scanning has no effectiveness and may very well carry risks, it would be naive to think that routine use will not continue.

Unfortunately, medical doctors are inadequately educated in the basics of scientific method. It will be a struggle to close the gap between this new scientific data and clinical practice.

Verwysings

  • Beech, B. and Robinson, J. (1993). Ultrasound? Unsound . Association for the Improvement in Maternity Services Journal 5.
  • Campbell, S. and Little, D. (1980). Clinical potential of real-time ultrasound. In M. Bennett & S. Campbell (Eds), Real-time Ultrasound in Obstetrics . Oxford: Blackwell Scientific Publications.
  • Chassar Moir, J. (1960). The uses and values of radiology in obstetrics. In F. Browne & McClure-Brown (Eds), Antenatal and Postnatal Care (9th ed.). London: J. & A. Churchill.
  • Cnattingius, J. (1984). Screening for Intrauterine Growth Retardation . Doctoral dissertation, Uppsala University, Sweden.
  • Ewigman, B. G. et al. and RADIUS study group. (1993). Effect of prenatal ultrasound screening on perinatal outcome. New England Journal of Medicine 329(12).
  • Hassani, S. (1978). Ultrasound in Gynecology and Obstetrics . New York: Springer Verlag.
  • Nasionale Instituut van Gesondheid. (1984). Diagnostic ultrasound imaging in pregnancy. Consensus Development Conference Consensus Statement 5, No. 1. Washington, D.C.
  • Neilson, J. and Grant, A. (1991). Ultrasound in pregnancy. In I. Chalmers et al. (Eds), Effective Care in Pregnancy and Childbirth . Oxford, England: Oxford University Press.
  • Newnham, J. et al. (1993). Effects of frequent ultrasound during pregnancy: A randomised controlled trial. Lancet .
  • Newnham, J. (1992). Personal correspondence.
  • Oakley, A. (1984). The Captured Womb . Oxford, England: Blackwell Publishing.
  • Reece, L. (1935). The estimation of fetal maturity by a new method of x-ray cephalometry: its bearing on clinical midwifery. Proc Royal Soc Med 18.
  • Salmond, R. (1937). The uses and values of radiology in obstetrics. In F. Browne (Ed), Antenatal and Postnatal Care (2nd ed.). London: J. & A. Churchill.
  • Salveson, K. et al. (1993). Routine ultrasonography in utero and subsequent handedness and neurological development. British Medical Journal 307.
  • World Health Organisation. (1984). Diagnostic ultrasound in pregnancy: WHO view on routine screening. Lancet 2.

Excerpted and adapted from Pursuing the Birth Machine: The Search for Appropriate Birth Technology , copyright 1994 by Marsden Wagner, published by ACE Graphics. Available in the United States and Canada from the ICEA Bookcenter, (800) 624-4934 Fax (612) 854-8772.


Are Prenatal Ultrasounds Dangerous?

Several questionable sources are spreading alarms about the possible dangers of prenatal ultrasound exams (sonograms). An example is Christine Anderson’s article on the ExpertClick website. In the heading, it says she “Never Liked Ultrasound Technology.”

[She] has never been sold on the safety using Ultrasounds for checking on the fetuses of pregnant women, and for the last decade her fears have been confirmed with a series of studies pointing to possible brain damage to the babies from this technology.

Should We Believe Her?

Should we avoid ultrasounds because Anderson never liked them? Should we trust her judgment that her fears have been confirmed by studies? Who is she?

“Dr.” Christine Anderson is a pediatric chiropractor in Hollywood who believes a lot of things that are not supported by science or reason. Her website mission statement includes

We acknowledge the devastating effects of the vertebral subluxation on human health and therefore recognize that the spines of all children need to be checked soon after birth, so they may grow up healthy.

It also states that “drugs interfere… and weaken the mind, body, and spirit.” Anderson is a homeopath, a craniosacral practitioner, a vegan, and a yoga teacher. She advises her pregnant patients to avoid toxins by only drinking filtered water and only eating organic foods. She sells her own yoga DVD.

In her own pregnancies she refused ultrasound and other prenatal screening tests. This was her idiotic reasoning:

I trusted in my body’s innate wisdom that if the pregnancy was moving forward, then everything was going OK in my baby’s development.

Apparently on her planet if a pregnancy has not spontaneously aborted that means the baby is developing normally, and no abnormal child is ever born. And perhaps all the children are above average?

She believes in many alleged benefits of chiropractic that are not substantiated by any evidence. She says that our emotions create chemical changes in our bodies that can affect our developing babies and that chiropractic helps to keep those feel good chemicals flowing freely. She believes that chiropractic frees up any interference to the nervous system and since the nervous system controls all the functions in the body, chiropractic manipulations allow the organs to optimally process any toxins they encounter. She believes getting regular chiropractic care reduces labor times.

Based on this, I am not impressed by her medical judgment or her understanding of biology or science, but that doesn’t necessarily mean she is wrong about ultrasound. What does she say?

Alleged Risks of Ultrasound According to Anderson

  • Ultrasound heats the tissue and researchers suspect that the waves cause small local gas pockets which vibrate and collapse called cavitation. The gas can reach up to temperatures of thousands of degrees (Celsium) [sic] leading to production of potentially toxic chemical reactions.
  • Studies done on mice have shown intestinal bleeding caused by changes in the cells. Scientists conclude that there would be similar effects in humans.
  • Ultrasound has been linked to the following abnormalities:
    • Left handedness in children who are supposed to be right-handed. Although there is nothing inherently wrong with being left handed, the change is attributed to a subtle damage to the brain. Males are more affected than female fetuses, probably because the male brain develops later.
    • Early labor, premature birth, miscarriage, low birth weight, poorer health at birth, and perinatal death.
    • Increased learning disabilities, epilepsy, delayed speech development, dyslexia

    She also alleges that no studies have been done to prove the safety of these devices. This is demonstrably false.

    Risks According to Scientists

    Obstetricians and radiologists who have evaluated the peer-reviewed literature have found no evidence of harm except for an apparent correlation between ultrasound exposure and left-handedness (in males only!). Such odd-sounding correlations are usually not significant, and are mostly good for a chuckle.

    Experts place little reliance on the mouse studies, since the dosages tested were higher than what humans are exposed to and since no corresponding clinical consequences have been detected in humans. Nevertheless, they acknowledge theoretical reasons for concern, and they recommend that medically unnecessary ultrasounds be avoided under the precautionary principle.

    Does Routine Ultrasound Affect Outcomes?

    A large study (15,530 women) published in Die New England Journal of Medicine found that routine screening did not reduce perinatal morbidity and mortality. There were no significant differences in the rate of preterm delivery, distribution of birth weight, or outcomes within the subgroups of women with multiple gestations, small-for-gestational-age infants, and post-date pregnancies. Finally, the detection of major anomalies by ultrasound examination did not alter outcomes. The authors pointed out that routinely screening more than 4 million pregnant women annually in the United States at $200 per scan would increase costs by more than $1 billion.

    A Finnish study found that perinatal mortality was significantly lower in the screened than in the control group (4.6/1000 vs 9.0/1000) but this was attributed to improved early detection of major malformations which led to induced abortion. All twin pregnancies were detected before the 21st gestational week in the screening group compared with 76.3% in the control group perinatal mortality in the small series of twins was 27.8/1000 vs 65.8/1000, respectively.

    Caveats: These studies did not look for long-term consequences like learning disabilities. And there are other considerations besides morbidity and mortality. Ultrasound can reassure patients or allow them to plan ahead for multiple births or abnormal infants, and it can guide obstetric management.

    Reasons for Doing Ultrasounds

    Ultrasounds can detect fetal abnormalities and can help guide obstetric care by detecting problems like multiple fetuses and placenta previa. There are many legitimate reasons for doing them, especially in high-risk pregnancies or when a specific problem is suspected.

    Reasons for Not Doing Routine Ultrasounds

    False alarms can be raised. Apparent abnormalities may cause worry but turn out not to be significant. Placenta previa detected early in pregnancy frequently resolves before delivery.

    There is no way to completely rule out the possibility of a low risk of long-term consequences. Trying to identify such consequences by even the most careful epidemiologic studies is fraught with pitfalls, since if you look for every possibility you will inevitably find a few spurious correlations. Experts agree that routine ultrasound screening is not necessary in low-risk pregnancies and that ultrasounds for nonmedical reasons should be discouraged.

    Some nonmedical uses are particularly objectionable. Ultrasounds are being used in India and elsewhere to determine sex for the purpose of aborting undesired female fetuses. Ultrasound is being commercially promoted for “keepsake” pictures and movies like this 5 minute video. Tom Cruise was roundly criticized by doctors for buying his own ultrasound machine for home use.

    There is no reason to fear prenatal ultrasounds that are ordered by science-based medical professionals and performed by qualified technicians, but it seems prudent to exercise caution and not do them for frivolous reasons.

    Considering that Anderson practices homeopathy, subluxation-based chiropractic, and craniosacral therapy, disparages drugs, and manipulates the spines of newborn infants, I think her own practices are far more worrisome than the ultrasounds she fears.


    Is Your Doctor Ordering Too Many Ultrasounds?

    Summary: Moms-to-be are getting more ultrasounds than is medically indicated &mdash an average of 5.2 per delivery, up 92 percent since 2004, according to new data reported on by The Wall Street Journal. The American College of Obstetricians and Gynecologists (ACOG) recommends getting one to two scans per low risk pregnancy &mdash and it's estimated that 75 percent of all pregnancies are considered low-risk.

    For moms-to-be, ultrasounds are often the most exciting part of your doctor's visit. Not only do you get to see your little bundle of joy for the first time, there's some peace of mind in knowing that he's safe and healthy inside of you. Ultrasounds can also serve as a bonding tool, to let new moms know that this is really happening &mdash those daily kicks are actually your growing baby. But although seeing your little guy or girl is reassuring and exciting, experts warn against getting too many ultrasounds when they're not medically necessary.

    According to research analyzed and reported on by The Wall Street Journal and compiled by the non-profit FAIR Health, doctors gave an average of 5.2 ultrasounds per delivery. The study included more than 150 million individuals, some of whom were high-risk patients. That means the number could have been inflated because high-risk pregnancies &mdash for example, moms-to-be with chronic conditions like type 2 diabetes,high blood pressure, lupus or growth restricted fetuses &mdash often require more constant scanning.

    That said, although high-risk pregnancies do require more frequent ultrasounds, an estimated three in four pregnancies are low-risk. Experts recommend that additional scans should not be used unless necessary or for recreational purposes to provide a sneak peak at baby. So while fetal ultrasounds are considered safe when used infrequently, we don't know the long-term side effects for sure, according to Dr. Jeffrey A. Kuller, Professor of Obstetrics and Gynecology in the Division of Maternal-Fetal Medicine at Duke University Medical Center. That's mostly because no scientist would knowingly put a fetus at risk of potential harm to study the effects of ultrasounds.

    ACOG recommends one to two ultrasounds per pregnancy:

    • An earlyultrasound at 10 to 12 weeks to establish due date and whether the pregnancy is viable. This scan is used to confirm the fetal heartbeat and a uterine (as opposed to ectopic or tubular) pregnancy, for example.
    • A more detailedanatomy scanat 18 weeks to screen for fetal growth, placenta location and umbilical cord, as well as the baby's general health and anatomy.

    Additional ultrasounds, including 3D and 4D ultrasounds, should only be performed if the mother is considered high-risk or if there's a suspected fetal abnormality &mdash which means you should avoid those offered outside a doctor's office as keepsakes along with at-home Doppler ultrasound machines.

    Dr. Kuller says that beyond these necessary scans, ultrasounds have the potential for negative, unintended risks.

    "While fetal weight is reasonably accurate, within about 10 percent, if the ultrasound under-estimates or over-estimates weight, patients can end up with unnecessary C-sections or premature deliveries in some cases," says Dr. Kuller. "Patients should also be warned that doctors can't rule out all defects or chromosomal abnormalities using ultrasound."

    A variety of factors seem to be contributing to the dramatic increase in ultrasound scans. Increased pressure from patients who want both a keepsake of their baby-to-be and assurance that he or she is thriving inside the womb are part of the picture, but Dr. Kuller contends there's more to it.

    "We live in a medical climate where doctors are constantly afraid of getting sued," he says. "Scans give patients and doctors assurance that things are good, and fear of litigation pushes doctors to do more testing in everything, including ultrasounds. I think the average patient is probably getting scanned more than they need to be."

    What this means to you. There's no doubt about it: A view inside the womb is exciting! And since it's impossible to know for sure what's going on in there otherwise, seeing your baby moving on-screen can put to rest some fears. However we don't know the long-term side effects of ultrasounds on the developing fetus for sure, which means unnecessary scans could have some unintended consequences. The best plan of action? Get a scan at 10 to 12 weeks and another at 18 weeks, per ACOG's recommendations. If your doctor requests more than that, ask questions and make sure what you're receiving is medically necessary for the optimal health of your baby-to-be.


    Side effects of ultrasound therapy

    Ultrasound therapy is used for treating many conditions such as cancers, tumors, dental conditions, and many others. In most of these, ultrasound is used physically, to establish diagnosis or to provide an image of certain internal organs or parts of our body, making it easy to track down any problems or possible illnesses. However, it can also be used when fighting tumors or relaxing one’s body, though these cases are far less frequent.

    The Good Side

    The ultrasound has two good sides. Firstly, it is an excellent tool for fighting cancerous cells, cysts, tumors, bacteria and numerous others. Secondly, it is known to speed up the healing process of our organism significantly, some claiming that in certain situations it provides even a 30% faster healing process.

    The Bad Side

    Unfortunately, there are those as well. One of them is the so called “cavitation”. This mainly manifests through pain and burning sensation the patient feels during exposure. Namely, the gas in the nuclei of our tissue cells gets heated, thus causing this pain and discomfort or even nausea, breathing problems and disorientation.

    We see that even though most doctors claim this therapy to be completely safe and recommended, there may be certain problems caused by it. Regardless, any overexposure to these sound frequencies may be dangerous. That being said, if pain and or kind of discomfort are felt during the ultrasound treatment, one should complain immediately and stop the treatment since the frequencies, if wrong, may cause permanent tissue damage and may even harm one’s nervous system.

    Furthermore, this therapy should not be applied over certain body parts or under some specific conditions. Pregnant women or women having their periods should not have their pelvic regions, their lower abdomen or back exposed to ultrasound treatment. Also, our eyes, sex organs or female breasts are not suitable for this treatment. Ultrasound frequencies should not be applied over certain bone fracture, skin wounds or malignant tumors of any sorts. Additionally, people with pacemakers or breast implants should avoid ultrasound as well.

    Finally, even though the ultrasound treatment has proven to be quite effective, some still doubt it’s worthiness claiming that it does nothing that other similar treatments involving heat or stretching could not do. There have also been cases of diverse efficiency, where the therapy worked on some people, while on others it did not.

    The most important thing is that it can and is beneficial and life-saving in some cases. Nevertheless, one should bear in mind all the negative sides of it and be careful, using only the best the ultrasound treatment has to offer.


    Studies have shown that ultrasound is generally safe. There are no known harmful side effects and there is virtually no discomfort during the test. In addition, ultrasound does not use radiation, as X-ray tests do. Although there are no known risks, ultrasound can heat up tissues in the body slightly and can also cause small gas pockets (known as cavitation) to form. The possible long-term effects of these are not known.

    Before the Ultrasound

    Generally, no special preparation is needed for an ultrasound. Depending on the type of test, you may need to drink fluid before the ultrasound or you may be asked to fast for several hours before the procedure.


    Future trends of imaging in cancer

    There are extraordinary future opportunities for imaging techniques in tumor biology evaluation, including the development of imaging biomarkers and radiomics/radiogenomics, the use of multiparametric analysis and artificial intelligence, and theranostic. To date, most research has been focusing on validating biomarkers extracted from tissue or blood samples, which has improved patient stratification and assisted oncologic drug development. Imaging techniques can evolve into clinically useful biomarkers for tumor assessment and evaluation of therapy response. The advantages of imaging are its versatility, its widespread disponibility, its capability of evaluating whole tumor burden, and its relatively noninvasive nature [140,141,142,143,144]. Adequate quantification of imaging biomarkers is of paramount importance when extracted data are going to be used in patient management. In this setting, data must be reproducible and the technology used to extract them must be standardized. Biomarkers precise a complex process of validation and qualification [140, 143]. On the other side, in recent years, imaging has been boosted by the technological development generating a large volume of data. Such information has increased in complexity and may offer prognostic value and may reveal meaningful information for decision-support in cancer diagnosis and treatment. Radiomics refers to the extraction and quantitative analysis of tumor characteristics from medical images. On its part, radiogenomics investigates the relationship between imaging features and gene expression. The -omic approach is based on numerical calculus and computer science methods, allowing the management and analysis of a very large number of variables for each sample and modality. There is a rapid increase in the number of publications that have highlighted the utility of imaging -omics in many different tumor types and based on different imaging techniques [145,146,147,148,149,150,151,152,153,154,155]. Radiomics and radiogenomics approaches may show clinical utility for assisting in cancer diagnosis, assessment of tumor aggressiveness, response assessment, and evaluation of patients’ outcome. Integrating (quantitative) imaging data with other relevant information (clinical, pathological, etc.) and multi-omics (genomics, proteomics, and metabolomics) will be essential for unraveling tumor heterogeneity and making real-time clinical decisions for patients in personalized medicine. However, this process still necessitates improvement and standardization in order to achieve routine clinical adoption. In this scenario, computers may be useful tools for the assessment of tumor characteristics and for the evaluation of therapy response. Computers can learn (machine learning) to extract meaningful patterns (including patterns that are beyond human perception) by processing massive datasets (big data) through mathematical models (algorithms). Machines can also correct algorithm mistakes by training. Machine learning algorithms are just useful components of computer-aided diagnosis and decision support system in oncology. Imaging representation and interpretation of tumor biology will require computational models to understand and predict the complex nonlinear dynamics that result in combinations of imaging features [156,157,158]. 3D printing is also an emerging computer-based technique that may be useful in oncology for research, surgical planning (using an exact 3D model of the patient’s organs to practice a procedure), device designing and manufacturing, and tissue or organ replacement [159]. The analysis of multi-dimensional imaging datasets is also increasingly required for imaging tumor phenotype. The correlation between imaging features obtained with different techniques must be explored for understanding the underlying tumor biology (Fig. 21). Significant differences in vascular, physiological, and metabolic characteristics have been identified in metastatic and nonmetastatic cancers. In this setting, high glycolytic activity and poor perfusion (vascular-metabolic mismatch) result in an aggressive tumor phenotype [160]. Finally, advances in the understanding of cancer biology together with developments in diagnostic technologies, and expansion of therapeutic options have all contributed to the concept of personalized cancer care with accurate and specific targeting of cancer cells. Theranostics is the systematic integration of targeted diagnostics and therapeutics. Imaging may select the therapeutic choice and may monitor subsequent changes in the biological characteristics of the tumor [161, 162].

    In conclusion, clinical imaging has tremendous potential in the evaluation of a wide spectrum of biological tumor characteristics at all stages of a cancer patient’s management and in drug discovery. Imaging techniques have also the ability to show the spatial and temporal heterogeneity of tumors (Fig. 22). In the time of precision oncology, clinical imaging represents a basic decision-making tool in cancer patients.

    Colorectal cancer liver metastasis in a 56-year-old man. FDG-PET (left) and b500 diffusion-weighted (middle) images demonstrated the presence of a mismatch between the obtained parameters. Note that the size of the FDG abnormality is smaller than the diffusion one (black arrow) (right). Tumor biology may explain this feature. Higher FDG uptake occurs at the edge of the necrotic cavity (white arrow) which is of relative low SI on b500 image. The edge of the necrotic cavity usually represents an area of relative tumor hypoxia, which may promote a high metabolic activity (vascular metabolic-mismatch). On its part, the periphery of the mass generally presents good perfusion and it is the most cellular area of the tumor, explaining the restricted diffusion at this level

    Whole-body DWI evaluation in a 72-year-old man with metastatic prostate cancer treated with (docetaxel + prednisone). A comparison between images pre (left) and posttherapy (right) demonstrated that tumor volume decreased (1280 cm 3 → 640 cm 3 ) and mean ADC moved from 0.7 to 1.61 confirmed an increasing % of voxels at higher ADC values after therapy consistent with reductions in cellularity due to tumor necrosis. However, tumor response was heterogeneous in this patient and there were some anatomical areas that presented a limited tumor response (black dotted circle on lumbar spine and black arrows)