Alternative Names foetal scalp blood, foetal scalp sampling
Definition In this procedure, a small amount of blood is taken from a baby's scalp. It is done while the mother is in labour. This is to determine if the baby is getting enough oxygen during the birth process.
Who is a candidate for the procedure? A baby's health during labour is measured through foetal monitoring. Sometimes, labour complications occur that can interfere with the working of the placenta. This could result in the baby not getting enough oxygen to the brain, a condition known as hypoxia. If the baby's heart rate becomes abnormal, and the baby is in foetal distress, foetal scalp sampling can indicate if there is enough oxygen going to the brain to safely continue labour. Otherwise, a caesarean section, may have to be performed right away to prevent further problems. Sometimes, foetal scalp sampling is also used to check the baby's platelet count, which is associated with the clotting ability of the blood.
How is the procedure performed?
The woman in labour lies on her back or side with her knees bent. Her cervix, which is the lower part of the uterus should be at least 3 centimetres 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. Foetal blood is extracted through a long tube placed at the site of the cut. This sample is immediately analysed to measure the amount of oxygen in the blood. The acid level (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. At this point a decision is made whether to let the labour continue or to perform a caesarean section. Other factors influencing the outcome are the mother's medical condition, the amount her cervix is dilated, and the severity of the baby's lack of oxygen. The baby's platelet count, which relates to the ability of the blood to clot, also affects the decision. If it is low, the baby runs the risk of intracranial haemorrhage or bleeding when passing through the birth canal. A caesarean section would be performed in this event.
What happens right after the procedure? Depending on the results of the test, a decision is made whether or not to continue with labour or to perform a caesarean section.
What are the potential complications after the procedure? Bleeding and infection are rare possibilities. The benefits of identifying foetal distress out weigh the small risk of the procedure.
Author: Eva Martin, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 12/06/2005 Contributors Potential conflict of interest information for reviewers available on request
