Difference in nuchal translucency between monozygotic and dizygotic spontaneously conceived twins

Abstract

During first-trimester ultrasonographic screening for Down syndrome, monochorionic twin pregnancies have the greatest NT thickness and monozygotic dichorionic twin pregnancies have the lowest inter-twin NT difference.

Impact of chorionicity on first‐trimester nuchal translucency screening in ART twin pregnancies

“…Overall, we observed a rather low rate of TTTS (4.7%), IUFT < 24 weeks of pregnancy (3.5%) and selective intrauterine growth restriction (9.6%). However, others described elevated NT thickness and inter‐twin NT difference in MC compared with DC pregnancies …”

“…However, others described elevated NT thickness and inter-twin NT difference in MC compared with DC pregnancies. 28…”

“…There are several reports about differences in NT thickness among monozygotic and dizygotic twins. In MC compared with DC twins, higher mean NT values and a larger inter‐twin NT difference have been observed . Both, increased and discordant NT thickness may also alert for early onset of twin‐to‐twin transfusion syndrome (TTTS) or other complications in MC pregnancies …”

“…In MC compared with DC twins, higher mean NT values and a larger inter-twin NT difference have been observed. 13 Both, increased and discordant NT thickness may also alert for early onset of twin-to-twin transfusion syndrome (TTTS) or other complications in MC pregnancies. 14,15 Measurement of foetal NT thickness is currently the most investigated and least affected screening method in ART singletons.…”

First-trimester Ultrasound and Aneuploidy Screening in Multifetal Pregnancies

“…There are controversial data whether twins have a higher FPR due to the increased incidence of enlarged NT measurements observed in monochorionic pregnancies, almost 1.5 times larger compared with dichorionic twins, as suggested by Sebire et al 37 and Cheng et al 38 It is thought that this increased fetal NT is an early manifestation of TTTS 28,29 ; however, this finding is not consistent in other studies, which have noted nonsignificant differences in mean NT measurements between dichorionic twins, monochorionic twins, and singletons. 35,39 FIRST-TRIMESTER SCREENING First-trimester aneuploidy screening combining NT with serum markers (free B-hCG and PAPP-A) is well established in singleton pregnancies, with a detection rate of 82% for Down syndrome with a 5% FPR.…”