Amniocentesis is performed between weeks 15 and 20 of the pregnancy. The procedure is preceded by an ultrasound, which reveals the length of the pregnancy, the number of foetuses, and the placental location. The examination also inspects the anatomy of the foetus, which can help detect possible deformities. As there is no evidence of ultrasound affecting the pregnancy, it can be performed repeatedly throughout the pregnancy if needed.
A small sample of amniotic fluid is taken with a thin needle through the abdominal wall, under continuous ultrasound guidance. This feels similar to having a blood test. Afterwards the mother can resume normal activity and return to work.
The amniotic fluid contains cells from the skin and membranes of the foetus, which are separated from the fluid and sent to a laboratory for chromosome analysis. The results are available in approximately two weeks.
Does amniocentesis involve risks?
Amniocentesis in early pregnancy is rarely harmful, but the procedure is not entirely risk-free. The sampling does not damage the foetus when performed by an experienced doctor under ultrasound guidance. Even from week 16, approximately 1-2% of pregnancies end in miscarriage. Amniocentesis carries a miscarriage risk of 0.5%. The results of the chromosome analysis are extremely reliable.
D.Med.Sc., Specialist, Obstetrics and Gynaecology and Specialist, Perinatology
Docent, Specialist, Obstetrics and Gynaecology
Docent, Specialist, Obstetrics and Gynaecology and Specialist, Perinatology
LT, naistentautien ja synnytysten erikoislääkäri, lisääntymislääketieteen lisäkoulutus, seksuaalineuvoja
Docent, Obstetrics and Gynaecology and Specialist, Perinatology