Amniocentesis
What is Amniocentesis?
Amniocentesis is an invasive prenatal diagnostic procedure performed between 15 and 20 weeks of pregnancy. It involves collecting a small amount of amniotic fluid, which contains fetal cells and biochemicals, to analyze for genetic, chromosomal, and biochemical conditions.
Why is it done?
- Diagnose chromosomal abnormalities (e.g., Down syndrome, Trisomy 18).
- Detect neural tube defects (e.g., spina bifida).
- Evaluate fetal lung maturity in high-risk pregnancies.
- Identify certain inherited metabolic disorders.
When should I get it?
Amniocentesis is typically performed between 15 and 20 weeks of gestation to minimize risks and ensure sufficient fluid volume for analysis.
How is the procedure done?
- Under ultrasound guidance, a sterile needle is inserted through the abdominal wall into the amniotic sac.
- Approximately 15–20 mL of amniotic fluid is withdrawn into a syringe.
- The fluid sample is sent to the laboratory for genetic and biochemical testing.
- The procedure takes about 20–30 minutes and is performed under local anesthesia.
Benefits and Risks
Benefits:
- Definitive diagnosis of many genetic and chromosomal conditions.
- Provides information for pregnancy management and counseling.
Risks:
- Miscarriage risk around 0.1–0.3%.
- Possible leakage of amniotic fluid.
- Infection or Rh sensitization (anti-D may be given).
Frequently Asked Questions (FAQs)
Do I need to prepare for amniocentesis?
No special preparation; a full bladder is not required.
Is the procedure safe?
Amniocentesis is generally safe but carries a small risk of miscarriage (<0.3%).
Will it hurt?
Local anesthesia minimizes pain; you may feel pressure or mild cramping.
When will I get the results?
Genetic results are available in 7–10 days; biochemical tests may be faster.
What if results are abnormal?
Your doctor will provide counseling and discuss management options.