Introduction: Molar pregnancies belong to a group of diseases classified as gestational trophoblastic diseases, which result from an altered fertilization. Partial molar pregnancy with a live fetus is a very rare condition, occurring in 0.005 to 0.01% of all pregnancies; it presents a challenging diagnosis, especially when clinical signs are almost completely absent.
Case presentation: Here we report a rare case of partial molar pregnancy in which a normal-appearing male fetus with diploid karyotype was delivered at 31 weeks gestation by a 37-year-old white woman. The pregnancy was characterized by an episode of threatened abortion in the first trimester and an ultrasonographic diagnosis of intrauterine growth restriction. Our patient did not report any suspicious symptoms for trophoblastic disease. Due to impaired umbilical artery velocimetry with an absence of the diastolic phase, she underwent an emergency caesarean section at 31 weeks and delivered an 880 g male baby. The male baby was normal without any complications at 3-month and 12-month follow-up and the mother had no evidence of recurrence after 3 and 12 months of follow-up. Pathological examination of the placenta showed changes of partial hydatidiform mole.
Conclusion: Partial molar pregnancy with a live fetus is a very rare condition that presents a challenging diagnosis. Recognizing it is of primary importance for patient care and the placenta should always be investigated at birth, especially in a newborn with intrauterine growth restriction.
Keywords: Gestational trophoblastic disease; IUGR; Misdiagnosis; Partial molar pregnancy; Placental histologic examination.