Partial molar pregnancy and coexisting fetus with diploid karyotype.

Objectives: To evaluate cases of partial hydatidiform mole coexisting with a live fetus, including an observation of our own, and to discuss the proper antenatal management of women wishing to continue with a partial molar pregnancy.
Method: A PubMed search was then undertaken, extending over the time period from 1975 to 2006, using the keywords 'partial hydratidiform mole', 'hydatidiform mole' and 'coexisting fetus'.
Results: At 16 weeks of gestation, an ultrasonographic examination revealed a normal fetus with an extremely large, multicystic placenta. The woman was informed of future risks but wished to continue with the pregnancy. The pregnancy progressed until 28 weeks without any complication but ended spontaneously with a vaginal delivery; the fetus had died in utero. Pathologic examination of the placenta revealed areas of hydropic degeneration and necrosis. Including our own observation, 17 cases of partial hydatidiform mole associated with a fetus of normal karyotype have been documented.
Conclusion: Although the rate of adverse perinatal outcome is high, we still believe that if amniocentesis or fetal blood sampling reveals a normal karyotype, then continuing the affected pregnancy with close follow-up in tertiary centers is a feasible choice.