Definition

Alternative Names

Placental Biopsy

Who is CVS recommended for?

Chorionic Villus Sampling is recommended for women who:

• Are pregnant and over the age of 35
• Have a family history of genetic problems
• Had other tests that indicate the fetus may have health problems
• Already have children with birth defects
• Have a chromosome abnormality
• Have a different blood type than their baby
• Will have an early delivery and need to check if the baby's lungs are developed

What are the benefits of the procedure?

• It can detect nearly all chromosomal abnormalities, including Down Syndrome and sex chromosome abnormalities
• It can detect several hundred genetic disorders, including Cystic Fibrosis, Sickle Cell disease, and Tay-Sachs disease
• It is performed 5 to 7 weeks sooner than an Amniocentesis
• It has a 99% detection rate for chromosome abnormalities

What is Chorionic Villus Sampling?

The chorionic villus sampling procedure is completely voluntary. The patient will meet with a genetic counselor prior to the procedure to discuss the risks and benefits involved. Ultimately, the patient decides whether or not she would like to have the procedure.

Chorionic villus sampling is usually performed between the 11th and 14th week of pregnancy. The doctor will ask the patient to empty her bladder when she arrives at the hospital, and to drink two glasses of water while meeting with the genetic counselor. The patient has no dietary restrictions.

Chroionic villus sampling can be performed through the vagina (transvaginal), or through the abdomen (transabdominal). The patient's physician will choose the safest approach that will fit that patient's needs. Both approaches use an ultrasound to determine the position of the uterus, the size of the amniotic sac, and the position of the placenta within the uterus.

The transvaginal method is most commonly performed. The procedure is done if the placenta is located on the back wall of the uterus. It is performed by inserting a thin tube through the vagina and up the cervix to reach the placenta. The chorionic villi cells that are located on the placenta are gently removed through the tube. The cells are then sent to a lab for testing. The patient may have a small amount of vaginal bleeding and cramping after having the procedure. Women generally describe the procedure as being similar to a Pap smear.

The transabdominal procedure is done if the placenta is located on the front wall of the uterus. It is performed by inserting a needle though the abdomen and uterus to reach the placenta. The needle draws a sample of the chorionic villi cells that are located on the placenta. The cells are removed at the spot where the placenta is attached to the uterine wall. The cells are then sent to a lab for genetic testing. This is similar to an amniocentesis.

Both methods of performing chorionic villus sampling may take anywhere from 30-45 minutes, although the extraction itself will only last a few minutes. The patient should let her doctor know if she has an active sexually transmitted disease or if she has had any bleeding during her pregnancy.

The chorionic villus sampling procedure does not require an overnight stay at the hospital. Final results from both the transvaginal and the transabdominal chorionic villus sampling procedures are typically available 10-14 days after the sample is extracted.

After the procedure, the patient needs to call her doctor if she experiences:

• Excessive bleeding
• Loss of amniotic fluid vaginally
• Fever
• Severe cramping
• Infection

There is a very small risk of having a miscarriage after the procedure.

Rehabilitation

Patients should avoid heavy lifting and strenuous activity for 2-3 days after having the procedure. Patients should also avoid sexual intercourse and the use of tampons after transvaginal chorionic villus sampling.

1/20/2009