First trimester diagnosis of partial mole

Partial mole is one of the two distinctive subtypes of hydatidiform mole. It is usually paternally derived triploid conceptions in which embryonal development occurs in association with trophoblastic hyperplasia. The definite diagnosis is confirmed by pathological and cytogenetic studies. Ultrasound might be helpful to diagnose partial mole in the first trimester.

A 25-year-old woman, gravida 2, para 0-0-1-0, was initially seen for antenatal care at 6 weeks' pregnant. Ultrasound was undertaken at 13 weeks' pregnancy due to her first fetal anomaly, which demonstrated partial mole and embryonic death. The serum beta hCG was 190,900 mIU/ml. Suction curettage was performed without complication. Histopathological study confirmed partial mole and cytogenetic study of the placenta revealed an uncommon karyotype, mosaicism of triploid (69,XXX/69,XXY). Serum beta hCG was declined and negative at 8 weeks. The patient was well and serum beta hCG remained normal throughout 6 months of follow-up.

Although the majority of partial mole pregnancies cannot be detected by routine first trimester ultrasound examination, first trimester ultrasound can be helpful in some cases, such as this one. If partial mole is sonographically suspected, it should be confirmed with histopathology and cytogenetic studies. The management is similar to complete mole including prompt evacuation and careful monitoring of beta hCG.