Risks of CVS and amniocentesis

Chorionic villus sampling takes a small sample from the placenta. It is usually offered earlier than amniocentesis, and the sample can provide information about certain genetic or chromosomal conditions. Amniocentesis removes a small amount of amniotic fluid around the baby, generally later in pregnancy. Ultrasound is used to guide the procedure and avoid the baby and placenta where possible.

Possible effects include brief cramping, spotting, fluid leakage, infection, or an unsuccessful sample. There is also a small chance of pregnancy loss. The risk depends on timing, technique, your medical history, placental position, and the experience of the service. Your clinician can explain what applies to you.

Before either test, share your blood group, medicines, allergies, bleeding conditions, and any infection symptoms. Ask when results are expected and whether you need a follow-up appointment. Rest if you feel crampy afterwards, use only pain relief approved for pregnancy, and follow the clinic's instructions about activity. Non-invasive prenatal testing, or NIPT, may provide screening information, but it does not answer every question in the same way as a diagnostic test.

Contact the maternity unit promptly after CVS or amniocentesis if you have heavy or continuing bleeding, fluid leaking from the vagina, fever, worsening pain, chills, contractions, or feel faint. Seek emergency help for severe abdominal pain, collapse, or difficulty breathing. Do not wait for the planned results call when symptoms are concerning.

Ask why a test is being offered, what it can and cannot detect, how the procedure will be guided, and which risks are relevant to your pregnancy. Discuss alternatives, including NIPT, and ask how a result could affect your care before deciding.