What Is Percutaneous Umbilical Blood Sampling (PUBS)? This quick test — also called cordocentesis, fetal blood sampling, or umbilical vein sampling — examines fetal blood directly from the umbilical cord. It's used to detect disorders in the fetus. PUBS isn't done as commonly as other diagnostic tests (such as amniocentesis and chorionic villus sampling), but may be used if results from those tests are not conclusive. Why Is Percutaneous Umbilical Blood Sampling Done? Percutaneous umbilical blood sampling usually is done in addition to an ultrasound and amniocentesis if a health care provider: needs to quickly check a baby's chromosomes for defects or disorders is concerned that the baby may have another problem, such as a low platelet count or a thyroid condition The advantage to PUBS is its speed. If the fetus might be anemic or have a platelet disorder, this test is the only way to confirm it because it uses a blood sample rather than an amniotic fluid sample. It also allows transfusion of blood or needed fluids into the baby while the needle is in place. Should I Have Percutaneous Umbilical Blood Sampling? Your health care provider may recommend this test if: an abnormality was noted on an ultrasound results from other tests aren't conclusive Rh incompatibility might be an issue the baby might have an infection (such as toxoplasmosis) Risks are associated with PUBS, such as miscarriage or infection. Discuss the risks and benefits with your health care provider if you choose to have this test. What Happens During a Percutaneous Umbilical Blood Sampling? This test takes a fetal blood sample by guiding a needle into the umbilical cord. A fine needle is passed through the abdomen and uterus into the umbilical cord, then the blood is withdrawn for testing. When Are Percutaneous Umbilical Blood Samplings Done? Percutaneous umbilical blood sampling usually is done after the 18th week of pregnancy. When Are the Results Available? PUBS results usually are ready within 3 days. Back to Articles Related Articles Prenatal Tests: First Trimester Find out what tests may be offered to you during the first trimester of pregnancy. Read More Prenatal Tests: Second Trimester Find out what tests may be offered to you during weeks 13 through 26 of pregnancy. Read More Prenatal Tests: Third Trimester Find out what tests may be offered to you during weeks 27 through 40 of pregnancy. Read More Prenatal Tests: FAQs Every parent-to-be hopes for a healthy baby, but it can be hard not to worry. Find out what tests can keep you informed of your health — and your baby's — throughout pregnancy. Read More Prenatal Test: Ultrasound A prenatal ultrasound is a safe and painless test that shows a baby's shape and position. It can be done in the first, second, or third trimester of pregnancy. Read More Prenatal Genetic Counseling Genetic counselors work with people who are either planning to have a baby or are pregnant to determine whether they carry the genes for certain inherited disorders. Find out more. Read More Prenatal Test: Multiple Marker Test The multiple marker test is a blood test done to screen for neural tube defects and chromosomal disorders. Read More Folic Acid and Pregnancy One of the most important things you can do to help prevent serious birth defects in your baby is to get enough folic acid every day - especially before conception and during early pregnancy. Read More Medical Care During Pregnancy The sooner in pregnancy good care begins, the better for the health of both moms and their babies. Here's what to expect. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.