Fetal blood testing involves the examination of a blood sample from a baby's scalp vein. It is done while the mother is in labor.

Who is a candidate for the procedure?

Fetal blood testing measures the oxygen to the baby's brain during labor. It can help determine if it is safe to continue labor. A fetal blood test is also used to check the baby's platelet count. This measures the clotting ability of the baby's blood.

How is the procedure performed?

The woman in labor lies on her back or side with her knees bent. Her cervix, or uterine opening, should be at least 3 centimeters dilated. A small round cone is inserted into the vagina. It is placed into the dilated cervix and against the baby's scalp.

The baby's scalp is cleaned to prevent contamination. A small cut is then made in the scalp. Fetal blood is extracted through a long tube placed at the site of the cut. This sample is immediately analyzed to measure the amount of oxygen in the blood. The acid level, or pH, and carbon dioxide content of the blood is also checked.

A low blood pH level indicates that the baby is getting too little oxygen. The baby's platelet count is also measured.