Comparison of bilateral and unilateral umbilical artery diastolic blood flow abnormalities in monochorionic diamniotic twin pregnancies

Abstract

Aim: Our study aimed to clarify the prognosis of bilateral and unilateral umbilical artery end-diastolic blood flow abnormalities (BFAs) in monochorionic diamniotic twin pregnancies.Methods: Monochorionic diamniotic twin pregnancies were classified into bilateral (group 1), unilateral (group 2), and no (group 3) umbilical artery end-diastolic BFAs. After the usual obstetric management, short- and long-term prognoses were analyzed.Results: A total of 171 monochorionic diamniotic twins were analyzed and classified into group 1 (13 twins, 7.6%), 2 (12 twins, 7.0%), and 3 (146 twins, 85.4%). Gestational age at delivery was significantly lower in group 1 than in groups 2 and 3 (median, 29.3, 35.6, and 35.6 weeks, respectively; p < .01 and p < .001). The survival rate of fetuses with BFAs was significantly lower in group 1 than in group 2 (23.0% [3/13] versus 100% [12/12]; p < .001). However, the survival rate of the co-twin was not significantly different between groups 1 and 2 (84.6% [11/13] versus 100% [12/12]; p = .48). The survival rate of both fetuses was significantly lower in group 1 than in groups 2 and 3 (53.8% [14/26], 100% [24/24], and 98.6% [288/292], respectively; both p < .001). In cases with fetal therapy, the survival rate of both fetuses tended to be lower in group 1 than in group 2 (44.4% [8/18] versus 83.3% [10/12]; p = .05). In cases without fetal therapy, the gestational age at delivery tended to lower in group 1 than in group 2 and was significantly lower than in group 3 (median, 29.1, 35.6, 35.6 weeks, respectively; p = .05 and p < .05). The survival rate of fetuses with BFA tended to be lower in group 1 than in group 2 (50.0% [2/4] versus 100% [12/12]; p = .05). The survival rate of the co-twin was not significantly different between groups 1 and 2 (100% [4/4] versus 100% [12/12]; p = 1). The survival rate of both fetuses tended to be lower in group 1 than in group 2 and was significantly lower than in group 3 (75% [6/8], 100% [24/24], and 99.2% [278/280], respectively; p = .05 and p < .01).Conclusions: In monochorionic diamniotic twin pregnancies, bilateral umbilical artery end-diastolic BFAs demonstrated a poor prognosis. However, unilateral abnormalities exhibited a good prognosis similar to that in twins with normal umbilical artery blood flow. If such abnormalities are detected during a routine checkup, the umbilical artery pulse wave on the other side should be examined.