Risk of donor demise after laser therapy for twin-twin transfusion when complicated by growth discordance and abnormal umbilical artery Doppler findings*

Objective: To investigate the natural course of abnormal umbilical artery Doppler (UAD) findings in donor fetuses after laser surgery and the prognostic significance of resolution, persistence, or new onset UAD abnormalities with and without the presence of preoperative growth discordance. Study design: Retrospective cohort study of all monochorionic-diamniotic multi-fetal gestations diagnosed with twin-twin transfusion syndrome (TTTS) undergoing laser surgery at a single large metropolitan referral center from 2010-2016. The estimated fetal weight was measured preoperatively and the UAD were measured both pre- and postoperatively (median = 8 days). Patients were grouped according to the presence of abnormal UAD with or without growth discordance pre- and postoperatively. Risk ratios (RR) were calculated for each group for risk of intrauterine fetal demise compared to the pre- and postoperative normal UAD groups as the referents. Results: There were eighty-one women who met inclusion criteria throughout the study period. Forty-three (53.1%) patients had abnormal donor twin UAD preoperatively and 33 (40.7%) were diagnosed with growth discordance. However, 13 (44.8%) had normalization of the UAD postoperatively (median = 8 days) with a similar rate of donor fetal demise as the non-discordant preoperative normal UAD group (7.7% versus 10.3%, p = .79). Abnormal preoperative UAD was associated with an increased risk of donor demise (RR 3.6, CI 1.1-12.1), which was further elevated in the presence of growth discordance (RR 5.2, CI 1.7-16.3). The greatest risk for donor demise was seen if the UAD remained abnormal postoperatively with concomitant growth discordance (RR 10.3, CI 2.5-41.6). Conclusions: Preoperative abnormal donor UAD is a significant risk for donor demise post-laser therapy for TTTS. Persistent postoperative abnormal UAD with concomitant growth discordance confers the greatest risk for donor demise. However, resolution of abnormal UAD has a similar rate of donor demise when compared to patients with normal UAD preoperatively.