[Prenatal diagnosis of trisomy 18 via hydramnion detected by echosonography (author's transl)].

Amniocentesis was prompted by an hydramnion which existed before the 30th week of pregnancy. Examination of amniotic fluid revealed trisomy 18 with increased alpha-fetoprotein values. Interruption of pregnancy was considered but refused by the patient. This enabled control fetal development during the subsequent weeks. After the patient has given birth to a dead female fetus in the 18th of pregnancy, pathological examination of the foetus confirmed the existence of trisomy 18.