Amniootsentese

Amniootsentese, commonly referred to as amniocentesis, is a prenatal diagnostic procedure in which a small amount of amniotic fluid is withdrawn from the uterus via a needle inserted through the mother's abdomen under ultrasound guidance. The collected fluid contains fetal cells and biochemical markers that can be analyzed to assess fetal genetics, metabolism, and well-being.

Indications for amniocentesis include screening for fetal chromosomal abnormalities (for example, trisomies such as Down syndrome), neural tube defects, certain genetic disorders, and fetal infections. It may also be used to determine fetal sex in specific clinical contexts and to assess fetal lung maturity later in pregnancy to help plan delivery in high-risk cases.

Timing and technique: amniocentesis is most commonly performed between about 15 and 20 weeks of gestation, though some indications may permit later sampling. The procedure is ultrasound-guided; a thin needle is passed through the abdominal wall into the amniotic sac, and a small amount of fluid (about 20 mL) is collected. The sample is sent to the laboratory for cytogenetic analysis (karyotype), molecular tests (such as chromosomal microarray), and biochemical assays.

Risks and limitations: as with any invasive procedure, amniocentesis carries risks, including miscarriage (rates typically around 0.1% to 0.5% in experienced hands), infection, rupture of membranes, and fetal injury or cramping. Not all conditions can be diagnosed by amniocentesis, and results may require confirmation or follow-up testing. Noninvasive prenatal testing from maternal blood is increasingly used as a screening tool, with diagnostic confirmation by amniocentesis or CVS when indicated.