Outcome of Twin Pregnancies Complicated by Single Intrauterine Death in Relation to Vascular Anatomy of the Monochorionic Placenta

The objective of this study was to determine the relationship between the type of placentation, vascular anatomy of the monochorionic (MC) placenta and the perinatal outcome of the surviving twin following a single intrauterine fetal death (IUFD). In this retrospective study, 92 twin pregnancies complicated by a single intrauterine death were identified from three tertiary referral centres [50 MC and 42 dichorionic (DC)]. Antenatal and neonatal data as well as information on the chorionicity, vascular anastomoses, and autopsy findings were also obtained. The percentage risk of IUFD (26 versus 2.4; P < 0.001), anaemia (51.4 versus 0; P < 0.001) and intracranial lesions at birth (46 versus 0; P < 0.001) was greater in MC than in DC twins. In MC twins without twin-twin transfusion syndrome (TTTS), perinatal mortality was higher in the group with superficial arterioarterial (AA)/venovenous (VV) channels than those with only multiple bidirectional arteriovenous (AV) anastomoses (12/15 versus 0/8; P < 0.001). However, in the TTTS pregnancies (n = 26), perinatal outcome of the surviving twin was dependent on whether the recipient (n = 16) or the donor twin (n = 10) died first. Incidence of IUFD (9/16 versus 0/10; P < 0.001), severe anaemia (7/7 versus 1/10; P < 0.001) and intracranial lesions at birth (6/7 versus 2/10; P < 0.001) was common in pregnancies where the recipient twin died first. In the TTTS group, unidirectional AV anastomotic channels were found in all but two placentae. In conclusion, this study suggests that the outcome of twin pregnancies complicated by IUFD is dependent on the type of vascular anastomoses and TTTS.