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Umbilical Cord Sampling

Percutaneous umbilical blood sampling (PUBS) is a prenatal diagnostic procedure in which a specially trained doctor extracts a sample of fetal blood from the vein in the umbilical cord. This sample of blood can be analyzed for:

• Certain chromosomal abnormalities
• Blood disorders such as hemophilia or anemia
• Some structural malformations of the fetus
• Some metabolic disorders
• Infections affecting the fetus, such as toxoplasmosis or rubella
• Intrauterine growth retardation
• Incompatibility between the mother and fetus’ blood type

This procedure is also utilized to perform blood transfusions on the fetus and to administer medication directly to the fetal blood supply. PUBS is also known as umbilical vein sampling, fetal blood sampling, and cordocentesis.

Dr. Lescale may suggest PUBS if ultrasound, amniocentesis, or chorionic villus sampling do not provide adequate information about the condition of the fetus. Also the procedure may be recommended if the doctor suspects the fetus may have an infection or blood disorder.

PUBS is similar to amniocentesis, but instead of sampling amniotic fluid that contains fetal cells fetal blood is extracted. With the aid of advanced imaging ultrasound the doctor inserts a fine needle through the woman’s abdomen into the fetal vein in the umbilical cord and extracts a sample of fetal blood. This blood is then sent to the lab to be analyzed. Results from the analysis are normally available very soon. Because the fetal vein in the umbilical cord is fragile in early pregnancy, the test is not performed prior to 18 weeks of gestation.

The risks associated with PUBS are a miscarriage rate of about 1%, infection, cramping, and bleeding. In each case Dr. Lescale explains the benefits of early diagnosis and the risks associated with the procedure so the mother can make an informed decision about pursuing testing.