Chorionic villous sampling

WHAT IS CHORIONIC VILLUS SAMPLING?

Chorionic villus sampling (CVS), or chorionic villus biopsy, is a prenatal test that involves taking a sample of tissue from the placenta to test for chromosomal abnormalities and certain other genetic problems. The placenta is a structure in the uterus that provides blood and nutrients from the mother to the fetus.

The chorionic villi are tiny projections of placental tissue that look like fingers and contain the same genetic material as the fetus. It is these villi which are used for genetic testing

WHAT IS THE PURPOSE OF CHORIONIC VILLUS SAMPLING?

Chorionic villus sampling may be used for genetic and chromosome testing in the first trimester of pregnancy.

Here are some reasons that a woman might elect to undergo CVS:

• Previously Affected Child Or A Family History Of A Genetic Disease, Chromosomal Abnormalities, Or Metabolic Disorder
• If An Ultrasound Identifies Structural Abnormality In the fetus.
• If Prenatal Screening Shows There Is An Increased Chance Of A Chromosomal Problem Like Down Syndrome,
• There may be other reasons for your doctor to recommend a chorionic villus sampling.
• Getting the test done is completely your choice. We can suggest what is good practice based on evidence-based medicine. Knowing all the pros and cons, you can accept or decline the testing.

WHEN IT IS DONE?

CVS is usually done between 11-13 weeks of pregnancy.

WHAT PRECAUTIONS ARE TAKEN PRIOR TO THE PROCEDURE?

The fetal medicine specialist will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure. You will be asked to sign few consent forms that gives the permission to do the procedure. There is no special restriction on diet or activity prior to chorionic villus sampling.

Your doctor will note if you are allergic to any medications, anesthetic agents (local and general), medications that you are taking, any history of bleeding disorders or any anticoagulant (blood-thinning) medications, aspirin, or any other medications that may affect blood clotting. It may be necessary for you to stop these medications prior to the procedure. Your blood group will also be noted and if you are Rh negative, an injection anti-D will be given to you after the procedure.

How Is The Procedure Performed?

During the procedure of CVS , the doctor need to obtain a tissue sample from the placenta, which will be sent to a lab for analysis. The sample will be extracted through the abdomen(transabdominal).

These ultrasound waves will be used to help the doctor guide the needle through the abdominal wall and uterus to the placenta. The needle is used to collect a sample of the chorionic villus cells.

Before the procedure, the patient will have an ultrasound to confirm how far along the pregnancy is and make sure it’s possible to get a good sample for the test.

The amniotic sac where the baby is growing won’t be disturbed during the procedure. The procedure takes about 20 to 30 minutes from start to finish, and the extraction itself takes only a few minutes. Once the procedure is done, the doctor checks the baby’s heart rate.

Is CVS painful??

Even though local anesthesia is administered,some patients may experience some pain or discomfort in the abdominal area.

When Is CVS Not Recommended?

When the patient has an active infection

When the patient has experienced vaginal bleeding during pregnancy

How accurate is the CVS report??

CVS has an accuracy rate of 98%. However, there are 1 to 2% chances of getting an unclear report. This is called confined placental mosaicism. Under this situation, the situation is confirmed with further testing.