Twin pregnancy with a complete hydatidiform mole and surviving co-existent fetus

Introduction Twin pregnancy with complete hydatidiform mole and co-existent fetus (CHMF) resulting in a healthy take-home baby is rare, with only 30 cases documented in detail in the literature. Case report A 29-year-old woman conceived following two cycles of ovulation induction with clomiphene citrate. Successive ultrasound examinations demonstrated a normally growing live fetus alongside a normal placenta and an additional intrauterine echogenic mass with features of hydatidiform mole. At 17 week gestation, serum beta-hCG level was 25.38 multiples of the median. Genetic amniocentesis at 18.5 week gestation showed normal fetal 46XX karyotype. A cesarean section performed at 28 week gestation resulted in the delivery of a live normal female infant and two adjoining placentas. One placenta was normal and the other placenta was composed of vesicles of various sizes. Microscopic examination of the abnormal placenta confirmed complete hydatidifrom mole. The baby did well and serial maternal serum beta-hCG levels showed a declining trend and were undetectable by 7 weeks after delivery. Conclusion Continuation of a twin pregnancy with CHMF is an acceptable option. There is, however, an increased risk of developing pre-eclampsia and fetal loss due to miscarriage. The chance of a live term birth is < 50% with nearly 33% of the mothers developing persistent gestational trophoblastic disease after delivery. Thus, close surveillance of an ongoing twin pregnancy with CHMF is mandatory to detect potential early signs of maternal and fetal complications.