Amniocentesis

A prenatal procedure sampling amniotic fluid for genetic and fetal lung testing

Definition

Amniocentesis is a diagnostic procedure in which a sterile needle is inserted through the abdominal and uterine walls, guided by ultrasound, to withdraw a small sample of amniotic fluid. It is used for genetic testing (typically 15 to 20 weeks) and fetal lung maturity assessment (late pregnancy).

Indications

Advanced maternal age (≥35)
Abnormal prenatal screening results (cfDNA, quad screen)
Family history of genetic disorders
Rh isoimmunization monitoring
Lecithin/sphingomyelin (L/S) ratio ≥ 2:1 indicates lung maturity

Risks

Miscarriage (1 in 300 to 500), infection, fetal injury, Rh sensitization in Rh-negative mothers, amniotic fluid leakage, preterm labor.

Nursing Considerations

Obtain informed consent and verify baseline fetal heart rate. Have the patient empty her bladder after 20 weeks (full bladder pre-20 weeks). Monitor fetal heart rate and uterine activity for at least 30 minutes post-procedure. Administer RhoGAM to Rh-negative mothers. Teach patients to report fever, contractions, bleeding, or decreased fetal movement.

NCLEX Relevance

Focus on post-procedure monitoring for fetal distress and maternal complications. Distinguish from chorionic villus sampling (earlier, 10 to 13 weeks) which cannot assess lung maturity.