Invasive Tests

Chorion Villus Sampling (CVS)

What is Chorion Villus Sampling?

Chorion Villus Sampling (CVS) involves analyzing chorionic villi (placental tissue). Since both the placenta and the baby originate from the same cells, the chromosomes in the placenta are identical to those in the baby.

How is CVS Done?

1. A local anesthetic is administered.
2. A fine needle is passed through the abdomen to collect a sample of the placental villi.
3. The procedure is performed under ultrasound guidance to ensure accuracy.
4. The process lasts about 1 minute, and afterward, the fetal heartbeat is checked.

What Should I Expect After CVS?

• For the first 1-2 days, you may experience:
  
  • Abdominal discomfort
  • Period-like pain
  • Light bleeding
    These symptoms are common and do not usually lead to complications. In most cases, the pregnancy continues without any issues.

When Will I Receive the Results?

• Down syndrome and major chromosomal defects: Results are available within 3 days.
• Rare defects: Results take about 2 weeks.
  You will be notified by phone as soon as the results are available.

Will the Procedure Need to Be Repeated?

• In approximately 1% of cases, the test may need to be repeated due to inconclusive results.

What Are the Risks of CVS?

1. Miscarriage: There is a 1% risk, similar to the risk of amniocentesis at 16 weeks. If a miscarriage occurs, it typically happens within 5 days of the procedure.
2. Risk of limb abnormalities: When CVS is performed before 10 weeks, there is a small risk of abnormalities in the baby’s fingers or toes. To avoid this, CVS is only performed after 11 weeks of pregnancy.

Amniocentesis

What is Amniocentesis?

Amniocentesis involves examining cells in the amniotic fluid surrounding the baby. The chromosomes in these cells are the same as the baby’s chromosomes.

How is Amniocentesis Done?

1. A thin needle is passed into the uterus to extract a small amount of amniotic fluid.
2. The needle’s progress is monitored through an ultrasound scan.
3. The extracted fluid, which is primarily fetal urine, is replenished by the body within a few hours.
4. The procedure lasts 1 minute, followed by a check of the fetal heartbeat.

What Should I Expect After Amniocentesis?

• You may experience mild abdominal discomfort or period-like pain for a couple of days.
• Pain relief: You can take paracetamol to ease discomfort.
• Seek medical advice immediately if you experience:
  
  • Severe pain
  • Heavy bleeding
  • Loss of fluid from the vagina
  • Fever or high temperature

Comparison of CVS and Amniocentesis

Both procedures are essential diagnostic tools used to identify chromosomal and genetic abnormalities in the fetus.