PUBS stands for Percutaneous umbilical cord blood sampling, which is also called cordocentesis. This Percutaneous umbilical cord blood sampling is generally a genetic test which is done for examining the blood from the fetal umbilical cord to detect fetal abnormalities. Percutaneous umbilical cord blood sampling is also done for rapid chromosome analysis because sometimes the information cannot be obtained through amniocentesis, CVC or ultrasound. For these tests umbilical cord blood are required which can be get from the umbilical cord blood storage facilities. But this test are very dangerous because these test carries a risk of complications which is typically reserved for pregnancies determined to be at high risk for genetic problem.

For understanding PUBS it is necessary to understand, what is umbilical cord? The connecting cord between the developing embryo and fetus to the placenta is called the umbilical cord. It is also called birth cord or funiculus umbilicalis. The umbilical cord normally contains two arteries and one vein. These cords are composed of Wharton’s jelly, rather than ordinary skin and connective tissue. The vein helps in carrying oxygenated, nutrient rich blood. And the arteries help in carrying deoxygenated, nutrient depleted blood. It is very unusual to hear that the vein carries the oxygenated blood and on the other hand the artery carry the deoxygenated blood. But it is true. The vein continues towards the fissure of the liver from where it splits into two. After splitting one of the veins joins with the hepatic portal vein which carried blood into the liver and the second one flow via the hepatic vein into the inferior vena cava which carried blood to the heart. This second one also allows the incoming blood to bypass the liver. Before joining the umbilical cord these two branches pass on either side of the urinary bladder.

These samplings (PUBS) are similar to amniocentesis. But there is one major difference also, in PUBS the fetal blood are examined other the other hand in amniocentesis the amniotic fluid which surrounds the fetus are sampled. For inserting the needle into the placenta an imagined ultrasound is done in advance. The needle which is inserted is guided through the mother’s abdomen and uterine wall into the fetal vein of the cord and then the fetal blood sample is removed. After that the sample is sent for chromosomal analysis. The whole process takes about 1 hr. One more important thing is that these tests (PUBS) cannot be performed before 17 weeks into pregnancy.

In a turnaround time of 72 hours the chromosomal abnormalities can be detected in the PUBS testing. Other than chromosomal abnormalities, blood disorder, infections, metabolic disorder are also detected. In PUBS there is very high risk of miscarriage. And this occurs in 1-2% of procedures. Other than these there are some other risks also such as blood loss at the puncture site, infection, and premature rupture of membranes. All these things occur rarely but there are chances of these things. And all should know about these risks before testing. Most of the time, the mother feels discomfort at the time of testing.