Hydatidiform mole with a surviving coexistent fetus following in-vitro fertilization

A case of a hydatidiform mole with a surviving coexistent fetus following in-vitro fertilization and embryo transfer is reported. The diagnosis was established at 12 weeks gestation and pregnancy was maintained until 31 weeks, during which time transient hyperthyroidism and lung metastasis developed. No difference was observed in pronucleus formation and early embryonic development between the two embryos, which resulted in a complete mole and a normal fetus. DNA finger-print analysis, karyotype analysis and histopathological examination confirmed that the pregnancy was a twin of a complete mole and a normal conception. DNA fingerprint analysis was performed with a single-locus probe cocktail. All DNA bands from the tumour were of paternal origin, and the bands from the placenta were of paternal and maternal origin.