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Cordocentesis is usually done in an outpatient facility or the health care provider's office, but in some cases it may be done in the hospital. At least one assistant will likely help your health care provider during the procedure.
During the procedure
About 30 to 60 minutes before the procedure, you may be given antibiotics to reduce the risk of a uterine infection.
When the procedure begins, your health care provider will use ultrasound to determine the baby's exact location in your uterus. You'll lie on your back on an exam table, and your health care provider will apply a special gel to your abdomen. He or she will then use a small device known as an ultrasound transducer to show your baby's position on a monitor.
Next, your health care provider will clean your abdomen with an antiseptic. Generally, anesthetic isn't needed. Most women report only mild discomfort during the procedure.
Guided by ultrasound, your health care provider will insert a thin, hollow needle through your abdominal wall and into your uterus. A small amount of blood from the vein in the umbilical cord will be withdrawn into a syringe, and the needle will be removed.
You'll need to lie still while the needle is inserted and the blood is withdrawn. You may notice a stinging sensation when the needle enters your skin, and you may feel cramping when the needle enters your uterus. The entire procedure usually takes about an hour, although most of that time is devoted to the ultrasound exam. Your baby will naturally replace the small amount of blood that's removed.
Rarely, a blood sample can't be taken from the umbilical cord. In these cases, a blood sample may be taken from a vein in the fetal liver.
After the procedure
After cordocentesis, your health care provider may use ultrasound or an external labor monitor to watch your baby's heart rate. You may experience cramping or a small amount of vaginal bleeding immediately after the blood sample is taken. Your health care provider may suggest resting after the procedure. You may want to ask someone to drive you home. You'll likely be able to resume normal activities the next day.
If you experience fever, chills or vaginal bleeding, contact your health care provider right away.
Meanwhile, the blood sample will be analyzed in a lab. Test results are typically available within 72 hours.
- Ghidini A. Fetal blood sampling: Indications and invasive fetal therapy. http://www.uptodate.com/home/index.html. Accessed March 9, 2010.
- Ghidini A. Fetal blood sampling: Technique and complications. http://www.uptodate.com/home/index.html. Accessed March 9, 2010.
- Grace D, et al. Training for percutaneous umbilical blood sampling during Maternal Fetal Medicine fellowship in the United States. Prenatal Diagnosis. 2009;29:790.
- Diagnosing birth defects. American Congress of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp164.cfm. Accessed March 9, 2010.
- Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. March 30, 2010.
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