In Utero Bipolar Diathermy to Salvage a Phenotypically Normal Fetus in 45,X/46,XY Heterokaryotypic Monochorionic Twins

Abstract

Heterokaryotypic monozygotic twins are rare. We report a set of monochorionic diamniotic twins complicated with lethal malformations and hydrops in one fetus at menstrual age of 16 weeks’. Sonographic appearances and genetic am-niocentesis result suggested for 45,X and 46,XY heterokaryotypic twins. Coexisting polyhydramnios found in the sac of severely malformed 45,X fetus threatened miscarriage and premature delivery. To salvage the phenotypically normal male fetus, the hydropic 45,X co-twin was selectively terminated by occlusion of its umbilical cord with bipolar dia-thermy. Complete cessation of funicular flow was achieved, resulting in normalization of total amniotic fluid volume. A healthy 2200-gram baby boy was born at 38 weeks’. His neurodevelopment was intact at 2 years of age. His physical examination was significant for slight growth delay (15 percentiles), with 6% of 45,X mosaicism found in his peripheral blood. Owing to the rarity of the cases, limited data is available regarding an optimal treatment for heterokaryotypic monochorionic twins with discordant lethal malformation. Intrauterine intervention may be offered should demise or permanent disabilities are imminent to the apparently normal fetus.