Cordocentesis: Cord Blood Sampling

March 3, 2010

How A Cordocentesis Is Performed

Percutaneous umbilical blood sampling (PUBS) also known as cordocentesis, is a type of diagnostic test that takes some of the unborn baby's blood and examines it for fetal abnormalities. It is an invasive test performed by using an advanced imaging ultrasound and a thin needle. The ultrasound picture indicates the location of the juncture of the umbilical cord and placenta. A thin needle is guided via ultrasound through the abdomen and uterine walls in into the umbilical cord where a small sample of the baby's blood is drawn. The sample is then sent for analysis to a lab and the results are usually back within 72 hours. This procedure is not unlike amniocentesis. However, the fluid drawn in an amniocentesis is amniotic fluid, while in a cordocentesis, the fluid is blood.

Why Have PUBS? Testing For Defects

Performed after 17 weeks gestation, a cordocentesis is usually requested when information gleaned through amniocentesis, CVS, ultrasound is inconclusive or the information cannot be obtained any other way. This test is used to detect chromosome abnormalities, such as is found in Down syndrome, and blood disorders in the baby. It can also be used to diagnose malformations of the baby, infection or anemia in the baby, isoimmunization, and the fetal platelet count in the mother. It does not test for neural tube defects, as does the amniocentesis.

Risks Of PUBS

The cordocentesis can detect certain blood disorders and abnormalities with high levels of accuracy. However, it cannot detect the severity of the situation. It is considered to be a safe procedure, but it is invasive and it does pose the potential risk of miscarriage, which happens in about 2 out of every 100 procedures. There are other potential repercussions of this diagnostic tool that include loss of blood from the puncture site, infection, premature rupture of the membranes and a drop in the baby's heart rate. Fever, chills, and amniotic fluid leakage are also risk factors.

Pros And Cons of Having Percutaneous Umbilical Blood Sampling

There are advantages to having the test and confirming the diagnosis as it does provide opportunities for pursuing medical interventions. A couple can begin preparing for lifestyle changes that may be necessary in caring for a child with special needs. Support groups can be identified and resources gathered. A couple may also make a decision about carrying the baby to term.

For some people, the idea of doing the testing is a moot point. They may decline the test and opt out of additional testing for reasons such as being comfortable with having the baby regardless the outcome or deciding against it because of potential harm or risk to the developing baby. Others, for moral, religious, or personal reasons have determined that carrying the child to term in not optional and they will deal with the results when the time comes.

The important factor is to gain all the information possible, including risks and benefits of cordocentesis. Seek help from the medical provider to determine whether the benefits outweigh the risks.

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