Amniocentesis

This webpage will give you information about an amniocentesis. If you have any questions, you should ask your GP or other relevant health professional.

What is an amniocentesis?

An amniocentesis involves using a needle to remove some of the amniotic fluid that surrounds your baby in your uterus (womb). It can usually be performed from 15 weeks of your pregnancy. 

An amniocentesis can help find out if your baby has one of the following problems.

• A chromosome disorder such as Down’s syndrome.
• A genetic or hereditary disease such as cystic fibrosis or sickle cell anaemia.
• A neural tube defect such as spina bifida.
• A Rhesus problem.

However, an amniocentesis does not cover all possible problems.

In the later stages of pregnancy, an amniocentesis can show if you have an infection. It can also help find out how mature your baby’s lungs are, in case you need an early delivery or are in premature labour.

Are there any alternatives to an amniocentesis?

Chorionic villus sampling is a procedure that involves removing a small piece of the placenta and can be performed between 11 and 13 weeks. 

It is possible to have a detailed scan or a blood test but these tests can show only if your baby may have a problem.

What does the procedure involve?

Removing the fluid usually takes about 30 seconds.

Your obstetrician will place the needle in the skin, through your abdominal wall and into your womb (see figure 1). 

They will remove about 15mls of fluid (1 tablespoon). 

What complications can happen?

• Miscarriage
• Vaginal spotting or bleeding
• Premature rupture of the membranes
• Infection in the womb
• Discomfort or cramping
• Injury to the baby
• Failure to get the fluid at the first attempt
• Failed culture
• Uncertain results of your baby’s chromosome pattern
• Removing blood-stained fluid

How soon will I recover?

Your baby’s heartbeat will be monitored for a while using the ultrasound scan and then you will be able to go home. 

You should rest for the next couple of days.

Most results of an amniocentesis are normal.

Summary

An amniocentesis is usually a safe and effective way to help find out if there is a problem with your pregnancy.

Acknowledgements

Author: Mr Andrew Woods MBBS MRCOG FRANZCOG 

Illustrations: Medical Illustration Copyright © 2011 Nucleus Medical Art. All rights reserved. www.nucleusinc.com.

This document is intended for information purposes only and should not replace advice that your relevant health professional would give you.