A complete hydatidiform mole coexisting with a normal fetus was confirmed by variable number tandem repeat (VNTR) polymorphism analysis using polymerase chain reaction.

The diagnosis of a complete hydatidiform mole coexisting with a live fetus is often difficult because of the morphological similarity to a partial mole, but it is crucial to management in the postmolar course. We present a recent case in which DNA polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. DNA polymorphisms on three different variable number tandem repeat loci, which were detected by polymerase chain reaction, indicated that the cord/placenta and molar tissue were parental and androgenetic, respectively. Subsequently, the patient was admitted for chemotherapy of metastatic trophoblastic disease.