OP05.02: Single umbilical artery: is it a risk factor in multiple pregnancies?

Abstract

Objectives: To examine the association between a single umbilical artery (SUA) and perinatal outcomes in multiple pregnancies in an Australian tertiary referral centre. Methods: Multiple pregnancies with at least one fetus diagnosed with a SUA at the midtrimester scan between August 2003 and January 2011 were included in the study. All patients have undergone detailed morphology ultrasound examination at our unit. Colour Doppler was used to visualize the umbilical arteries adjacent to the fetal bladder and in a section of a free loop of cord. The diagnosis of a SUA was confirmed on histopathologic examination of placentae and umbilical cords. Results: Twenty-six fetuses with a SUA were identified in the study period and complete follow-up data were available for 22 cases. In all pregnancies included in the study only one of the fetuses of each multiple pregnancy had a SUA. Of the 22 fetuses comprising the study population, 13 were dichorionic twins, 5 MCDA twins, 1 MCMA twin and 3 triplets. Fifteen (68%) cases were isolated, i.e., no chromosomal or structural fetal anomalies were present. In 7 fetuses (32%) with a SUA there were structural anomalies and just one of them had a chromosomal abnormality (trisomy 18). Eight cases (36%) of fetal growth restriction (3 with structural anomalies) and 2 cases of twin-to-twin transfusion syndrome were detected. In terms of perinatal mortality there were 2 intrauterine fetal deaths and 2 neonatal deaths (18%), 1 selective termination (triplets to twins) and 1 cord ligation in a monochorionic twin with multiple abnormalities. The mean gestational age of delivery was 31 weeks with preterm delivery before 34 weeks happening in 15 cases (68%). Seven (32%) patients had a normal vaginal delivery and 15 (68%) a caesarean section. The mean birth weight was 1505 g in the cases of a SUA and 1643 g in the fetuses with 3 vessel cords. Conclusions: Our study shows that multiple pregnancies with at least one fetus with a SUA are at increased risk for adverse perinatal outcomes.