Amniocentesis is usually carried out in the 16th - 18th week of pregnancy. A very fine needle is inserted transabdominally and approx. 10 ml of fluid are removed from the amniotic sac. Local anesthesia is not required. The procedure usually lasts about 1 minute and is performed under constant ultrasound control.
Cells are cultured from the amniotic fluid for chromosomal analysis. The results are available about 10-14 days later. Upon request, the laboratory can carry out an additional rapid screening test (FISH, quick PCR), which gives a result after one or two days on the most common chromosomal abnormalities. In addition, the level of alpha-fetoprotein (AFP) in the amniotic fluid is determined. Elevated levels of AFP may indicate the development of spina bifida or an abdominal fissure. After genetic consultation, in special cases more tests can be performed for specific inherited diseases, such as metabolic disturbances. In rare cases, findings may be unclear, thus necessitating further examinations.
The risk of miscarriage from amniocentesis depends on the examiner and is usually given at around 0.25% - 1%. We recommend that patients go for a check-up examination with their regular gynecologist 1-2 days after the procedure, and that they avoid strenuous physical activity for a few days.