Spontaneous Twin Anemia Polycythemia Sequence: Diagnosis, Management and Outcome in an International Cohort of 249 Cases

Abstract Background Twin anemia polycythemia sequence (TAPS) is a chronic form of unbalanced feto-fetal transfusion through minuscule placental anastomoses in monochorionic twins, leading to anemia in the donor and polycythemia in the recipient. Due to the low incidence of TAPS, data on diagnosis, management and outcome are scarce. Objective To investigate the diagnosis, management and outcome in a large international cohort of spontaneous TAPS. Study design Data of the international TAPS Registry, retrospectively collected between 2014-2019, were used for this study. Seventeen fetal therapy centers contributed to data collection. The primary outcomes were perinatal mortality and severe neonatal morbidity. Secondary outcomes included a risk factor analysis for perinatal mortality and severe neonatal morbidity. Results A total of 249 spontaneous TAPS cases were included in this study, of which 219 (88%) were diagnosed antenatally and 30 (12%) postnatally. TAPS was diagnosed antenatally at a median gestational age (GA) of 23.7 weeks (IQR: 19.7-28.8; range: 15.1-35.3). Antenatal management included laser surgery in 39% (86/219), expectant management in 23% (51/219), delivery in 16% (34/219), intrauterine transfusion (with partial exchange transfusion) in 12% (26/219), selective feticide in 8% (18/219) and termination of pregnancy in 1% (3/219). Perinatal mortality rate was 15% (72/493) for the total group; 22% (54/243) for donors and 7% (18/242) for recipients (p Conclusions Spontaneous TAPS can develop at any time in pregnancy, from the beginning of the second trimester to the end of the third. Management for TAPS varies considerably, with laser surgery being the most frequent intervention. Perinatal mortality and severe neonatal morbidity were high, the former especially in donor twins.