Cordocentesis – A Diagnostic Test for Fetal Abnormalities

Also known as fetal blood sampling or Percutaneous Umbilical Cord Blood Sampling (PUBS), cordocentesis is a diagnostic test mainly used to examine the blood of the fetus for detecting fetal abnormalities.

This prenatal testing is used to diagnose in utero complications along with Down syndrome and heart defects.

How is the test performed?

Advanced imaging ultrasound is used to find the area where the baby’s umbilical cord joins the placenta.

During the procedure, a thin needle is passed through the abdomen and uterine walls to the umbilical cord to get a blood sample.

The only difference between this test procedure and amniocentesis test is that blood is retrieved from the fetus.

When is the test performed?

Usually, the test is done when the required information is inconclusive or cannot be obtained from amniocentesis, ultrasound or CVs.

Usually, the right time to undergo this test is when you are just above 17 weeks pregnant, i.e. after the complete development of the umbilical cord.

How is cordocentesis useful?

The test is used to detect chromosomal abnormalities such as Down syndrome and other blood disorders like fetal hemolytic disease. It also helps diagnose the following abnormalities:

  • Fetal anemia;
  • Malfunction of the fetus;
  • Isoimmunisation;
  • Fetal platelet count of the mother;
  • Fetal infections like rubella or toxoplasmosis;
  • Respiratory illnesses;
  • Congenital heart defects.

Cordocentesis differs from amniocentesis, in that testing is not allowed to detect neural tube defects in the latter. The procedure is also successful in treating parvovirus in a twin pregnancy.

Are there any risks associated with cordocentesis?

Though this procedure is considered as safe, it is identified as an invasive diagnostic test that does cause potential risks. There is 1 to 2% risk for miscarriage signs with a small risk of infection.

There is no need for anesthesia as it can cause slight discomfort,  cramps and contractions, both during the test and for some days after the procedure.

Some other potential side effects of cordocentesis include:

  • Infection;
  • Premature rupture of membranes;
  • Loss of blood at the punctured location;
  • Reduction of fetal heart rate;
  • Vaginal bleeding.

You should immediately contact your practitioner if any of the above-mentioned symptoms remain or become worse. Also, contact your healthcare provider if you notice:

  • Chills;
  • Fever;
  • Leakage of amniotic fluid.

After undergoing the procedure, you will be told to take complete rest for 24 hours.


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