Perinatal Outcome of Conservative Management versus Fetal Intervention for Twin Reversed Arterial Perfusion Sequence with a Small Acardiac Twin

Objective: To examine the outcomes of patients with twin reversed arterial perfusion (TRAP) sequence in which the acardiac twin was ≤50% the weight of the pump twin. Methods: This was a retrospective study conducted with institutional review board approval. The records of all patients referred to UCSF for suspected diagnosis of TRAP between 1994 and 2009 were reviewed (n = 76). Patients with pregnancies complicated by TRAP with an acardiac twin ≤50% the weight of the pump twin were included (21 patients). Exclusion criteria were loss to follow-up (1 patient) and syndromic abnormalities in the pump twin (2 patients). Results: Of the 18 patients with viable pregnancies that met the criteria for analysis, 7 (39%) underwent radiofrequency ablation (RFA) of the acardiac twin and 11 (61%) underwent conservative management. None of the pump twins in either group had hydrops fetalis. Three of the 11 acardiac twins in the conservative management group did not undergo RFA because they did not have blood flow at presentation to UCSF. Survival to delivery was 100% (7/7) in the RFA group and 91% (10/11) in the conservative management group. When we eliminated from our analysis the 3 pregnancies in the conservative management group without blood flow to the acardiac twin, survival to delivery was 88% (7/8). The single death occurred in 1 of the 3 monochorionic-monoamniotic pregnancies in the conservative management group, all of whom had blood flow to the acardiac twin. There were no statistically significant differences in gestational age at delivery, birth weight or survival between the RFA and conservative management groups, even after stratification by blood flow. Conclusions: Conservative management with close monitoring appears to be a safe option for TRAP pregnancies in which the acardiac twin is ≤50% the weight of the pump twin.