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Percutaneous umbilical blood sampling, also referred to as cordocentesis, is a prenatal test that is highly specialized in which a sample of fetal blood is obtained from the umbilical cord to be tested for infections or genetic problems. This test can be done at 18 weeks pregnant or later. This test is quick with the results being available in as little as two hours and as long as 72 hours. This test can also be done to transport medication and blood transfusions to the baby when the baby is still inside of the mother.
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Why is this Test Done?
This test is done to figure out key information concerning an unborn baby's health. This test is generally only done when no other tests provide the information needed and when the possible results could have a significant impact in the pregnancy and how it is managed. This test is used to identify:
- Blood disorders
- Restricted growth
- Chromosomal conditions
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How to Prepare for this Test
Patients are able to eat and drink normally before having percutaneous umbilical blood sampling. The patient will be asked to sign a consent form and will be made aware of all of the possible risks. The patient may need to give a sample of blood prior to having this test done. The patient will also need to arrange to have a ride home after having this test done.
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What to Expect and How it is Done
Patients will be given antibiotics about thirty to sixty minutes prior to this procedure in order to decrease their chance of developing a uterine infection. Ultrasound will be done to figure out exactly where the baby is located. Antiseptic will be used to cleanse the abdominal area. A thin, hollow needle, guided by ultrasound, will be inserted into the uterus through the abdominal wall. The needle will puncture the umbilical cord vein and a small amount of blood will be drawn into a syringe. The needle is then removed.
Most women report that this procedure is uncomfortable, but not painful. The needle may sting when it pierces the abdominal wall and cramping can occur as the needle is inserted into the uterus.
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What do the Results Mean?
The patient's genetic counselor or health care provider will help them understand the results. If it is determined the baby has an infection, the patient's doctor will talk to them about the available treatment options. If it is determined that the baby has severe anemia, a blood transfusion, via the umbilical cord, may be necessary. Some patients will have to have their labor induced early. If it is determined that the baby has a chromosomal disorder, the parents with be faced with the decision of whether or not to continue with the pregnancy.
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What are the Possible Risks?
Various risks are associated with this procedure. These include:
- Slowing of the baby's heart rate
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Mayo Clinic. (2010). Cordocentesis. Retrieved on July 23, 2010 from the Mayo Clinic: http://www.mayoclinic.com/health/percutaneous-umbilical-blood-sampling/MY00147
American Pregnancy Association. (2003). Percutaneous Umbilical Blood Sampling. Retrieved on July 23, 2010 from the American Pregnancy Association: http://www.americanpregnancy.org/prenataltesting/percutaneousumbilical.html