Indications for amniocentesis: what to know

Amniocentesis uses ultrasound guidance to take a small sample of amniotic fluid around the baby. Cells in the fluid can be tested for selected chromosome or genetic conditions, depending on the reason for testing. It is a diagnostic test, so your clinician should explain what the planned test can and cannot show.

It may be discussed after a screening result that suggests increased chance of a condition, an ultrasound finding, a known family or genetic risk, or a previous pregnancy or child affected by a condition. Screening and diagnostic testing answer different questions: screening estimates chance, while diagnostic testing examines sampled genetic material.

Ask the maternity or genetics team why the test is being offered, what conditions will be examined, when results may arrive, and how results could change pregnancy or newborn care. Discuss the procedure, possible discomfort, bleeding, infection and the small risk of pregnancy loss in terms you understand.

You can ask about alternatives. NIPT is a screening blood test, while chorionic villus sampling takes placental tissue for diagnostic testing earlier in pregnancy in suitable circumstances. The right option depends on gestational age, the question being investigated and your preferences.

After amniocentesis, contact your maternity unit promptly for heavy bleeding, fluid leaking from the vagina, fever, worsening abdominal pain, contractions or feeling acutely unwell. Follow the specific aftercare instructions given by your team.

Before the procedure, seek urgent advice for bleeding, severe pain, fluid loss or reduced fetal movement when movement is expected. These symptoms need assessment whether or not amniocentesis is planned.

Ask what prompted the offer, which result is being sought, whether the test is diagnostic or screening, what alternatives are suitable, and how a result would affect care. Ask about timing, sample analysis, waiting for results and support while making your decision.