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What risks are involved in amniocentesis? - Carolyn in Holyoke, Colorado
The expert answers
Amniocentesis is a procedure during which a needle is passed, under ultrasound guidance, into the amniotic cavity ("bag of water") in order to extract amniotic fluid for evaluation. Fetal cells contained in the amniotic fluid can be cultured for karyotyping to detect chromosome anomalies, such as Down Syndrome. This procedure is typically done between 14 and 16 weeks of gestation. Also, at this time, if a neural tube defect (spina bifida, anencephaly, meningocele, encephalocele) is suspected, an assay for the presence of acetylcholine esterase (AchE) can be performed as a confirmatory test.
Later in pregnancy, it is sometimes necessary to document lung maturity prior to delivery. Certain substance/chemicals (lamellar bodies, phosphatidyl glycerol, lecithin/sphingomyelin ratio) can be assayed/calculated to help determine the status of lung maturity.
To rule out an intra-amniotic infection (chorioamnionitic), a culture of the amniotic fluid and/or Gram stain for bacteria can be performed.
Any invasive procedure has the potential for complications. With ultrasound guidance, the risk of complications is diminished, but is not completely eliminated. The most commonly associated complications associated with amniocentesis are:
- 1:1000 risk of intra-amniotic infection (chorioamnionitis)
- 1:100 risk of fluid leak ? typically self-limiting
- 1:200 risk of fetal loss (miscarriage)
Amniocentesis should not be considered a "routine" procedure, however, for many women, the benefits of this prenatal test outweigh the risks. If you have any questions or concerns about this test or your baby's well-being, be sure to talk to your doctor.