孕28周后胎盘附着于子宫下段

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1、PlacentapreviaTheplacentaprovidesthefetuswithoxygenandnutrientsandtakesawaywastesuchascarbondioxideviatheumbilicalcord.DefinitionPlacentapreviaisaconditionthatmayoccurduringpregnancywhentheplacentaimplantsinthelowerpartoftheuterusandobstructsthecervicalopeningtoth

2、evagina(birthcanal).孕28周后胎盘附着于子宫下段,其下缘甚至达到或覆盖宫颈内口,其位置低于胎儿先露部。IncidenceTheincidenceofplacentapreviaisapproximately1outof200births.increaseswitheachpregnancy,anditisestimatedthattheincidenceinwomenwhohavehad6ormorepreviousdeliveriesmaybeashighas1in20births.doubledin

3、multiplepregnancy(suchastwinsandtriplets).EtiologyEndometriumfactors:ascarredendometrium(liningoftheuterus)CurretageforseveraltimesanabnormaluterusPlacentalfactorsLargeabnormalformationoftheplacenta.DevelopmentretardationoffertilizedeggRiskfactorsincludemultiparit

4、y(previousdeliveries),multiplepregnancy,previousmyomectomy(removalofuterinefibroidsthroughanincisionintheuterus),andapreviousC-section(ifthescarislowandclosetothevaginalcervixregion).classificationCompleteplacentapreviaPartialplacentapreviaMarginalplacentapreviaCl

5、inicalfindingsSymptomsSpottingduringthefirstandsecondtrimestersSudden,painless,andprofusevaginalbleedinginpregnancyduringthethirdtrimester(usuallyafter28weeks)--Bleedingmaynotoccuruntilafterlaborstartsinsomecases--Anemia,shockSignsTheuterusisusuallysoftandrelaxed.

6、Theinfantpositionisoblique(//)ortransverse(==)inabout15%ofcases.Fetaldistressisnotusuallypresentunlessvaginalbloodlosshasbeenheavyenoughtoinducematernalshock,placentaabruptio,oracordaccidentoccurs.Nodigitalexamination!AccessoryexaminationsUltrasonography:Accuracy9

7、5%34thweekPostpartumexaminationofplacentaandmembrane7cmDiagnosisDifferentialdiagnosisComplicationsMaternalcomplicationsmajorhemorrhage,shock,anddeath.ImplantedplacentaAnemiaandinfectionFetalcomplicationsPrematurity(infantislessthan36weeksgestation)isresponsiblefor

8、about60%ofinfantdeathssecondarytoplacentaprevia.Fetalbloodlossorhemorrhagemayoccurbecauseoftheplacentatearingawayfromtheuterinewallduringlabor.Itmayalso