A dichorionic diamniotic (DCDA) twin pregnancy is a type of twin pregnancy where each twin has its own chorionic and amniotic sacs. This type occurs most ...×ArticlesLogInCasesSignUpCoursesQuizDonateAbout×MenuSearchADVERTISEMENT:Radiopaediaisfreethankstooursupportersandadvertisers.BecomeaGoldSupporterandseenoads.ArticlesCasesCoursesLogInLoginSignup{"url":"/signup-modal-props.json?lang=us\u0026email="}ArticlesCasesCoursesQuizAboutRecentEditsGoad-freeSearchDichorionicdiamniotictwinpregnancyDrYurangaWeerakkody◉andRadswiki◉etal.Adichorionicdiamniotic(DCDA) twinpregnancyisatypeoftwinpregnancywhereeachtwinhasitsownchorionicandamnioticsacs.Thistypeoccursmostcommonlywithdizygotic twins,butmayalsooccurwithmonozygotic twinpregnancies.Thistypeofpregnancymayhavecharacteristicfindingsonultrasound.Onthispage:Article:EpidemiologyPathologyRadiographicfeaturesComplicationsRelatedarticlesReferencesImages:CasesandfiguresEpidemiologyDCDApregnanciesaccountforthemajority(~76%)ofalltwinpregnancies.Theyaccountforalldizygoticpregnanciesand~20%ofmonozygoticpregnancies.PathologyEtiologyWithadizygoticpregnancy,twoovaareindependentlyfertilisedbytwospermleadingtotwozygotes. Withamonozygotictwinpregnancy,DCDApregnancyresultsfromtheseparationofthezygotesat~1-4dayspostfertilisation(morula)stage. RadiographicfeaturesUltrasoundSonographicassessmentofchorionicityismostaccurateinthefirsttrimester.FirsttrimesterFeaturessupportingaDCDApregnancy:presenceoftwogestationalsacswithathickechogenicchorionsurroundingeachembryoathickinter-twinmembrane (oftentakenas> 2mm)twinpeaksign (lambda(λ) sign)twoyolksacsmaybeseen(this,however,doesnotdifferentiateaDCDApregnancyfromamonochorionicdiamniotic(MCDA) pregnancy)Secondtrimesterwhenthereisnoplacentalfusion,twoseparateplacentalsitesmaybeseen4afindingoftwodifferentgendersforeachtwinisadefinitivefeatureforadizygoticpregnancywhichinturnwillinvariablymeanaDCDApregnancyIfthetwinsareofthesamegenderthenitisextremelydifficultifnotimpossibletodetermineiftheyaremonozygoticordiz