Antenatal Screening

	Ultrasound Scanning
	Amniocentesis
	Alpha feto protein Test (AFP)
	Chorionic Villus Sampling

Amniocentesis

During pregnancy your baby is safely cushioned by clear liquid called 'amniotic fluid', which is enclosed by a sac, made of a strong, waterproof material, called 'amnion'.
The amniotic fluid has several important properties which make it tremendously useful in prenatal diagnosis. Firstly, because the fluid is constantly recycled by the baby, it contains chemicals which reflect the baby's health, and secondly, cells are rubbed off the baby's skin, due to it moving about. When an amniocentesis is necessary, it is these cells that are used during testing.

How and why is it done?
An amniocentesis is carried out in the doctors consulting rooms or in a hospital, usually done at around 12-16 weeks. During this procedure, the doctor will extract a sample of amniotic fluid from the sac that surrounds the fetus. Using ultrasound, to allow a precise view of where to insert the needle, and to avoid touching the fetus. The doctor carefully guides the needle through the abdomen and the uterus into the amniotic sac. A small sample of fluid is then withdrawn, and sent to a lab for testing. Here the cells are grown in a special fluid for several days, before testing begins. If you are carrying twins, the doctor will need to take a sample from each sac.
The procedure takes about 10 to 20 minutes, with the results being available 3-4 weeks later.
This test allows the doctor to assess any chromosomal abnormalities or neural defects, that may be present, due to a family history of the condition. Many women complain of severe pain, while others experience only slight discomfort, so the severity of the pain you endure, probably depends on your personal pain threshold.

Are there problems with Amniocentesis?
Although, amniocentesis is extremely effective in detecting abnormalities, there are a few risks that have to be considered. Side effects that may occur include cramping, bleeding, infection and leaking of amniotic fluid after the procedure. Injury to the fetus is rare. There is a small risk of miscarriage following the procedure, so this and all other factors should be fully explained to you by your doctor - less than 1 in 200 women who have the test will have a miscarriage.