[Early sonographic determination of hydatidiform mole with a simultaneously developed fetus]

The incidence of hydatidiform mole with an associated foetus is between 1 in 10,000 and 1 in 100,000 pregnancies. Two cases are presented which are diagnosed prenatally before the 22nd week of gestation. They illustrate the two possible forms of molar pregnancy: Type I is characterised by large hydropic villi in a major discrete portion of the placenta. In Type 2 small hydropic villi are scattered diffusely all over the placenta. The characteristic clinical and microscopic differences between the two types of hydatidiform mole associated with foetus are outlined, among those the different risk for malignant development, the sex preferences and cytogenetic aspects. There is a high risk of pre-eclampsia already early in pregnancy. Sonography, HCG determinations and cytogenetic examinations are the basis for an early diagnosis and treatment of hydatidiform moles.