A procedure usually performed at 16-20 weeks of pregnancy in which an amniotic fluid sample is obtained under ultrasound guidance for chromosomal and genetic evaluation of the fetus.
Indication
- High risk identified on screening tests (dual, triple, quadruple test, NIPT)
- Increased risk of chromosomal abnormality due to maternal age or family history
- Suspicious structural anomaly seen on ultrasound
- History of chromosomal or genetic disease in a previous pregnancy
- Prenatal diagnosis in known carriers of genetic disease
- Evaluation of fetal lung maturity at advanced gestational ages (selected cases)
- Evaluation of suspected intrauterine infection
Preparation
- Detailed information is provided and informed consent is obtained before the procedure
- Fasting is not required; a light meal can be eaten
- Rh immunoglobulin (anti-D) preparation is planned for Rh-negative mothers
- Use of blood-thinning medications must be reported to the physician in advance
- Whether the bladder should be full or empty is determined by the physician according to the procedure
How it's performed
- The patient is positioned supine and the abdominal area is sterilized
- Using ultrasound, the appropriate pocket of the baby, placenta, and amniotic fluid is identified
- A thin, long needle is inserted through the abdominal skin into the amniotic sac under ultrasound guidance
- Approximately 15-20 ml of amniotic fluid sample is collected
- After the needle is withdrawn, the entry site is closed and the baby's heartbeat is checked
- The procedure typically takes 5-10 minutes; the sample is sent to a genetic laboratory
Post-procedure
- After the procedure, avoidance of heavy lifting, long travel, and intense activity is recommended for 24-48 hours
- Mild abdominal cramping or pressure sensation is normal; if fever, bleeding, fluid leakage, or severe pain occurs, consult a physician
- Anti-D immunoglobulin is given to Rh-negative mothers
- Results are usually available within 2-5 days for rapid tests and 2-3 weeks for full karyotype
- Genetic counseling and further evaluation are planned based on the results
Risks
- Risk of miscarriage is approximately 0.1-0.3% (in experienced hands)
- Mild vaginal bleeding or amniotic fluid leakage may occur
- Rarely, intrauterine infection may develop
- Very rarely, contact with the baby or placenta with the needle
- Risk of sensitization in Rh-incompatible mothers if anti-D is not administered
FAQ
When is amniocentesis performed?
Amniocentesis for genetic purposes is generally performed between 16-20 weeks of pregnancy. Performing it at earlier weeks may increase the risk of miscarriage.
Is amniocentesis painful?
During the procedure, a brief stinging at needle entry and a mild pressure sensation are usually felt. Severe pain is not expected.
What is the risk of miscarriage?
In experienced centers, the procedure-related risk of miscarriage is reported at approximately 0.1-0.3%. The decision is made by weighing this risk against individual risk-benefit balance.
What is the difference from NIPT?
NIPT (a screening test from maternal blood) is a screening tool and is non-invasive; amniocentesis is a diagnostic test that gives a definitive result. Amniocentesis may be recommended to confirm positive or high-risk NIPT findings.
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