Uncommon complications of monochorionic twin pregnancies: Twin reversed arterial perfusion sequence

Twin reversed arterial perfusion (TRAP) sequence occurs when there is one non-viable twin without cardiac structures and a viable pump twin that perfuses the acardiac mass. This study aims to investigate the management and immediate neonatal outcomes for monochorionic multiple pregnancies complicated by TRAP referred to the NSW Fetal Therapy Centre (NSW FTC).

Retrospective cohort study of multiple pregnancies referred to NSW FTC between April 2006 and April 2014, reviewing data for cases of TRAP sequence (n = 19, including two triplet cases) compared to a timeframe matched sample of uncomplicated monochorionic diamniotic (MCDA) twin pregnancies managed in the unit (n = 45).

Primary management of the 19 TRAP cases was expectant management in 10 (53%), radiofrequency ablation (RFA) in 6 (32%), and bipolar cord coagulation, amniodrainage and termination of pregnancy in 1 case each. 1 of 6 RFA cases had pump twin demise <1 week post-procedure. Average gestation at birth (35.1 ± 5.0 vs. 35.0 ± 2.8 weeks) and mean birthweight (2157 ± 1019 g vs. 2245 ± 537 g) were similar between TRAP pump fetuses and uncomplicated MCDA cases. Pump twin survival was 81% (twins only) compared to 98% for uncomplicated MCDA twins (P = 0.02), and in 5 of 19 (26%) TRAP pregnancies the pump fetus had a congenital anomaly.

Mean gestational age at birth and mean birthweight were similar for both TRAP and uncomplicated MCDA pregnancies. TRAP cases, however, had higher perinatal mortality, and high rates of congenital anomaly. The overall neonatal outcome at NSW FTC for TRAP cases is similar to reported international outcomes.