Invasive Fetal Medicine Procedures — Amniocentesis and CVS

Our approach to invasive procedures

Every patient considering an invasive procedure receives structured pre-procedure counselling: indications, what the result will and won’t tell, procedural technique, miscarriage risk (current data suggests below 0.5% in experienced hands), and what happens if a positive result is found. The procedure itself is performed under ultrasound guidance with continuous monitoring; recovery is typically uncomplicated.

Amniocentesis

Performed from around 15 weeks. A small volume of amniotic fluid is sampled transabdominally under ultrasound guidance. Fetal cells in the fluid undergo karyotyping or specific genetic testing. Used for diagnostic confirmation after positive screening, advanced maternal age combined with anxiety about uncertainty, or specific family-history indications.

Chorionic Villus Sampling (CVS)

Performed from 11 weeks. Placental tissue is sampled transabdominally or transcervically under ultrasound guidance. Allows earlier diagnostic information than amniocentesis. Used where early diagnosis materially affects decision-making.

Post-procedure care

Patients receive structured post-procedure information (warning symptoms, when to call), and we contact each patient personally with results. The conversation about a result — whether reassuring or otherwise — is unhurried.

Procedures covered

Guidelines we follow

• ISUOG practice guidelines on invasive prenatal procedures
• RCOG green-top guideline on amniocentesis and CVS
• FMF training standards for invasive procedures

Where this fits

Invasive procedures typically follow positive findings from screening or scans. Results inform decisions about specific conditions.