Amniocentesis and Chorionic Villus Sampling (Green-top Guideline No. 8)

Published: 25 October 2021

Summary

Pregnant women are offered amniocentesis or chorionic villus sampling (CVS) for prenatal diagnosis for a variety of reasons including a higher chance aneuploidy screening result, fetal structural anomaly, or a known risk of inherited genetic disease.

CVS is usually performed between 11⁺⁰ and 13⁺⁶ weeks of gestation. If required, CVS can be performed between 14⁺⁰ and 14⁺⁶ weeks’ gestation. Individualised counselling of the merits of CVS versus amniocentesis should be provided for women considering CVS during this time period. Amniocentesis, performed to obtain amniotic fluid for analysis, is usually offered from 15⁺⁰ weeks.

Version history

The first edition of this guideline was published in 1996; the second edition was published in 2000; the third edition was published in 2005; and the fourth edition was published in 2010. This is the fifth edition of this guideline, published in October 2021; reviewed 2024 – no update required: Next review date: 2026

Developer declaration of interests

Dr K Navaratnam: None declared
Professor Z Alfirevic: None declared.

Key points

• Women should be informed that the additional risk of miscarriage following amniocentesis or CVS performed by a skilled operator is likely to be below 0.5%.
•  Amniocentesis should not be performed prior to 15⁺⁰ weeks gestation.CVS should be performed between 11⁺⁰ and 13⁺⁶ weeks; it should not be performed prior to 10⁺⁰ weeks gestation.