Sometimes diagnostic testing is suggested to you by your doctor for reasons outlined below. It is important that you know what you are in for. CVS or chorionic villus is one such invasive test. It is usually carried out during the 1st trimester if your doctor suspects the fetus having any chromosome or biochemical abnormalities. This diagnostic test involves a sample or biopsy of the chorionic villi (tiny finger like projection on the placenta). These cells contain genetic information that can analyse chromosomal problems and inform you on your baby's gender as well if you like. This test is used to determine specific conditions like:
- Down's syndrome
- Cystic fibrosis
- Certain types of hemophilia
- Duchene's muscular dystrophy
- Turner syndrome
- Sickle cell anemia
- Fragile-X syndrome
- Antitrypsin deficiency
Who is the likely candidate for CVS testing during pregnancy
You may qualify for CVS if you:
- are over 35
- already have or had a child affected by one of the conditions listed above
- have a family history of one of these conditions
- have an 'increased risk' blood test result
- have a clue from the nuchal fold test that all is not right with the fetus
Although this test can detect chromosomal defects, don't count on it to test for Spina bifida. The safe period for testing is between weeks 10 and 12; CVS is able to indicate the presence of a problem much earlier than the other popular diagnostic test called amniocentesis. This test can be conducted in two ways: transvaginal and transabdominal. There isn't really much difference as both involve the ultrasound and the insertion of a catheter either through the vagina or abdomen. However check with your doctor on which method will be suitable for you. (Factors include the preference of your doctor, the position of the placenta and how advanced are you in your pregnancy).
The Down side of CVS is
- the main risk involved, which is miscarriage. According to some experts there is up to 30% chance of miscarrying
- it is not always accurate. If cells are inaccurately taken from the site, this test won't be able to offer any indication on the health of the unborn child.
- some abnormalities in chorionic tissues don't surface in the fetus. It is therefore important to seek a second opinion of any negative report before you decide on anything.
- it can be uncomfortable or even painful especially if it is done via the abdomen. Done vaginally, the sensation can be compared to a pap smear.
The Up side of CVS is
- the procedure is short, about 10-20 minutes
- it can be performed earlier and therefore you get to know the results sooner
- results take about a week and in some cases as early as 2 days
- since the preliminary results come earlier it is often less painful emotionally and physically easier if you decide to terminate a pregnancy involving a baby with an abnormality
The procedure itself
- you will need a full bladder
- you will be given an anesthetic if its transabdominal method
- you will need to lie still while the technician uses an ultrasound to see exactly where the baby is inside the sac
- a tube is then inserted either through your vagina or directly into your abdomen.
- The fresh cells are examined right away and some answers can be obtained within 48 hours after a CVS
After the CVS test
- Rest for at least 24 hours and take it easy for 3 days
- Expect to feel cramping pains and slight vaginal bleeding for 2 - 3 days
- Report to your doctor immediately if the blood loss is severe or goes beyond 3 days
- Also contact your doctor if you experience loose clear fluid as this may be amniotic fluid
- If everything is normal, you will receive the results through the post
- You can request that your report not state the gender findings; notify your doctor beforehand.