Early prediction of severe twin-to-twin transfusion syndrome

Abstract

This extended series of 303 monochorionic twin pregnancies examined at 10-14 weeks gestation explores the possible association of increased fetal nuchal translucency thickness (NT) in the early prediction of severe twin-to-twin transfusion syndrome (TTS). Of 303 pregnancies, there were 16 in which at least one fetus was structurally or chromosomally abnormal and in the remaining 287 ongoing pregnancies there were 43 (15%) which developed severe TTS. The median fetal NT was 1.0 multiples of the median (MOM) and NT was >95th centile in 47 (8.2%) fetuses and in at least one fetus in 37 (12.9%) pregnancies. The prevalence of increased NT in the pregnancies that developed TTS [17.4% (n = 15) of fetuses and 28% (n = 12) of pregnancies] was significantly higher than in the non-TTS group [6.6% (n = 32) and 10.2% (n = 25) respectively; Z: = -3.4, P: < 0.001 and Z: = 3.2, P: < 0.001 respectively], likelihood ratio of increased fetal NT for prediction of TTS = 3.5 [95% confidence interval (CI) 1.9-6.2]. In 153 of the pregnancies, an ultrasound examination was also performed at 15-17 weeks gestation and intertwin membrane folding was seen in 49 (32%) cases; 21 of these (43%) subsequently developed TTS compared to two (1.9%) of the 104 pregnancies without membrane folding (Z: = 6.6, P: < 0.001), likelihood ratio of membrane folding for prediction of TTS = 4.2 (95% CI 3.0-6.0).

Prevalence and perinatal outcome of dichorionic and monochorionic twins with nuchal translucency above the 99th percentile and normal karyotype

“…In chromosomally normal dichorionic twins, increased NT is likely to be due to an underlying mechanism similar to that in a singleton fetus, leading to a similar increased risk for adverse pregnancy outcome, although no specific data are available. However, in monochorionic twins, increased NT may also be produced by hemodynamic imbalances between the fetuses through the vascular anastomoses, which may result in severe early onset of TTTS 3,4 . Previous studies in singleton pregnancies have reported that an increased NT in a fetus with normal karyotype was associated with a poor pregnancy outcome, the chances of which increased exponentially with increasing NT thickness, from 8% when NT ranged between the 95 th and 99 th percentiles to 80-85% when the NT was above 6.5 mm 1,14 .…”

“…It has been suggested that this sign might constitute an early manifestation of TTTS 3,4 , but this notion has been questioned in more recent studies 5,6,22 . Therefore, it is suggested that this finding in a monochorionic twin should prompt a search for signs of TTTS.…”

“…Earlier reports suggested an association between increased NT (> 95 th percentile) in one fetus and subsequent development of twin-twin transfusion syndrome (TTTS) 3,4 , but according to recent studies this association is controversial 5,6 . In a recent series of monochorionic twins, a ≥ 20% discordance in NT was found to increase the risk of subsequent fetal demise or severe TTTS to more than 30% 7 .…”

A Coaxial Laser Endoscope with Arbitrary Spots in Endoscopic View for Fetal Surgery

“…Twin-to-twin transfusion syndrome (TTTS) occurs in about 15% of monochorionic twins, caused by imbalance in the net flow of blood between them across the placental communicating vessels [1,2]. The mortality rate of these twins exceeds 80%, and the risk of disability in the survivors is estimated to be 15-50% if untreated [3].…”

Ductus venosus in twins: science matters

“…Although the content is in many ways commendable, the disregard of previous pivotal publications relating to the topic is disappointing. On Page 251, when the authors discuss the implications of discordance in nuchal translucency thickness (NT) and crown-rump length (CRL), they ignore the clinically relevant contribution of abnormal flow in the ductus venosus (DV) in screening for twin-to-twin transfusion syndrome (TTTS).We know from the papers of Sebire et al 2,3 that a higher prevalence of increased NT was noted among monochorionic (MC) twins along with a four-fold increase in the risk of developing TTTS in this subgroup. An intertwin difference in NT of more than 20% was a stronger marker for TTTS, but its sensitivity was unsatisfactory (around 50%) 4 .…”