CVS - Chorionic Villus Sampling
Early diagnostic test collecting placental tissue to test for genetic and chromosomal conditions.
📅 When Performed
Weeks 10-13
⏱️ Results Timeline
Rapid results: 2-3 days; Full results: 1-2 weeks
Overview
Chorionic villus sampling (CVS) is a diagnostic test that collects a small sample of placental tissue to test for genetic conditions. Since the placenta develops from the same cells as the baby, it contains the same genetic information.
CVS can be performed earlier than amniocentesis (10-13 weeks vs. 15-20 weeks), allowing for earlier diagnosis of genetic conditions. This earlier timing can be important for families making decisions about the pregnancy.
The procedure can be performed through the abdomen (transabdominal) or through the cervix (transcervical), depending on placenta location. Like amniocentesis, CVS provides definitive genetic diagnosis rather than risk assessment.
🎯 Purpose of Test
- •Diagnose chromosomal conditions (Down syndrome, trisomies)
- •Test for inherited genetic disorders
- •Provide early genetic diagnosis (earlier than amnio)
- •Confirm abnormalities found on ultrasound
- •Test when family history of genetic condition
- •Definitive diagnosis by first trimester
🔬 How It's Performed
- 1.Two methods: transcervical (through cervix) or transabdominal (through belly)
- 2.Method chosen based on placenta location
- 3.Ultrasound guidance throughout procedure
- 4.Transcervical: Thin catheter through cervix to placenta
- 5.Transabdominal: Needle through abdomen (like amnio)
- 6.Small sample of chorionic villi collected
- 7.Takes 5-10 minutes
- 8.Rest recommended after procedure
👀 What to Expect
- →Procedure performed in office or hospital
- →Ultrasound used to visualize placenta
- →Brief discomfort or cramping
- →Transcervical may feel like pap smear
- →Transabdominal similar to amniocentesis
- →Spotting or cramping common after
- →Rest recommended for 24 hours
- →Results in 1-2 weeks (rapid results in 2-3 days)
✓ Normal Results
Normal chromosomes, no genetic abnormalities detected
⚠️ Abnormal Results
- •Chromosomal abnormality detected
- •Genetic disorder identified
- •Meet with genetic counselor
- •Discuss implications and options
- •Additional testing may be recommended
- •Rarely, confined placental mosaicism (abnormality only in placenta, not baby)
⚠️ Risks & Considerations
- •Miscarriage risk: about 1 in 200-500 (0.2-0.5%)
- •Slightly higher risk than amnio
- •Infection (rare)
- •Vaginal spotting or bleeding
- •Cramping after procedure
- •Amniotic fluid leakage (rare)
- •Rh sensitization if mother Rh-negative (RhoGAM given)
📝 How to Prepare
- →Full bladder may be needed for transabdominal
- →Bring support person
- →Arrange transportation
- →Plan to rest afterwards
- →Discuss concerns with doctor beforehand
- →Consider genetic counseling before test
- →Understand what conditions are being tested
- →Rh-negative women receive RhoGAM after