Large proximal intertwin vascular anastomoses as a rare cause of twin anaemia-polycythaemia sequence (TAPS): case report

Background: Twin anaemia-polycythaemia sequence (TAPS) is a form of chronic twin-to-twin transfusion syndrome (TTTS) secondary to slow unidirectional blood flow across minuscule arteriovenous (AV) anastomoses. We present case presumed TAPS unusual, large, proximal Case report: Monochorionic diamniotic (MCDA) twins were born at 25+6 weeks gestation following intrauterine fetal demise. Ultrasound scan two beforehand showed mild growth discordance (0.7%) with normal amniotic fluid volumes. At post-mortem, 1 (825g) appeared pale and 2 (770g) plethoric. Placental examination revealed side-by-side, fused cord insertions the extreme placental edge, one artery-to-artery (AA) anastomosis close insertion umbilical vein-to-umbilical vein (UV-UV) within 1's cord. All chorionic veins drained into 1’s UV anastomosis. Discussion: characterised by anaemia in donor twin polycythaemia recipient without oligohydramnios or polyhydramnios typically caused very small (<1 mm diameter) AV To our knowledge, this first reported associated large AA UV-UV The possibility acute exsanguination from demise cannot be excluded. Reference 1. Tollenaar LSA, Slaghekke F, Lewi L, et al. Spontaneous anemia polycythemia sequence: diagnosis, management, outcome an international cohort 249 cases. Am J Obstet Gynecol 2021; 224: 213.