Complete hydatidiform mole in higher-order multiple pregnancies

Molar degeneration of the trophoblast is a rare, yet possible, complication of pregnancies. Complete hydatidiform mole is the most common histological type among all trophoblastic tumors and it is the result of the fertilization of an empty oocyte from two sperms or by one sperm that then duplicates. Complete mole is characterized by hydropic degeneration of abnormal chorionic villi, diffused trophoblast hyperplasia and the absence of identifiable embryonic or fetal tissue; the hyperplastic trophoblast justifies the common finding of high serum beta HCG levels. Twin molar pregnancy is an uncommon obstetric event, and even less frequent are triplet/quadruplet molar pregnancies. We hereby report a case of a complete hydatidiform mole with two coexistent fetuses in a triplet pregnancy after in vitro fertilization procedure; the pregnancy ended with a therapeutic abortion. During the follow-up, the serum beta human chorionic gonadotropin concentration started to rise, and the diagnosis of post-molar gestational trophoblastic neoplasia was made and consequently methotrexate treatment was started. Due to the rarity of this condition, there are no specific guidelines for the management of multiple pregnancies complicated by complete hydatidiform mole. We therefore performed a review of the literature including all reported cases of triplets/quadruplets pregnancies complicated by complete mole of a fetus focusing on ultrasound diagnosis, treatment and outcomes of this rare and life-threatening condition.