<gynaecology, oncology, tumour> A relatively rare mass or tumour that can form within the uterus at the beginning of a pregnancy. The cause of hydatidiform mole is unknown.
Symptoms include vaginal bleeding, uterine growth, nausea and vomiting. Some hydatidiform moles may become malignant (cancerous) where they are referred to as a choriocarcinoma.
Incidence: 1 in 1,500 births.
(02 Jan 1998)