(GTN) a group of disorders characterized by persistence of gestational trophoblastic disease, with abnormal placental development and very high levels of human chorionic gonadotrophin (hCG). The chorionic villi are fluid-filled with vacuolation of the placenta and destruction of the normal stroma. GTN is rare in the UK, with a calculated incidence of 1/714 live births. It may develop after a molar pregnancy (see hydatidiform mole), a nonmolar pregnancy, or a live birth. The incidence after a live birth is estimated at 1/50,000. A malignant condition may develop (see choriocarcinoma) if the abnormal tissue is not completely removed and the risk of this is monitored by the fall in hCG levels. Choriocarcinoma complicates approximately 3% of complete moles, although in 50% of cases of choriocarcinoma there is no history of immediately preceding trophoblastic disease. It may also occur following a normal pregnancy. In the UK, there is an effective registration and treatment programme. The programme has achieved impressive results, with high cure (98–100%) and low chemotherapy (5–8%) rates.
Subjects: Medicine and Health.