A decade of mid-trimester amniocentesis in Johannesburg. Prenatal diagnosis, problems and counselling.

Selected data from 4,554 cases of amniocentesis performed in Johannesburg over a decade are presented. The demand for the service increased fivefold over the 10 years. The indications were: chromosome defects (83%), neural tube defects (11%), other disorders (4%) and parental anxiety (2%). A correct prenatal diagnosis was made in 99.9% of cases and sexing was correct in 99.6% of cases. Abnormalities were detected in 3.2% of pregnancies. The rate of 'spontaneous' abortion within 1 week after amniocentesis was 0.7%, and the total 16-28-week fetal loss rate is not much increased over the risk for such an event in any second-trimester pregnancy. The procedure has become a safe and a successful one in expert hands.