Prenatal Diagnosis - KP Genetics Northern California

Prenatal Diagnosis

Highlights

What is Prenatal Diagnosis?
Diagnostic Procedures
Results of Amniocentesis/CVS
Prenatal Ultrasound
Deciding whether to have a prenatal diagnostic procedure

Prenatal Testing for Birth Defects: A Guide to Helping You Decide

Summary

Purpose of prenatal diagnosis

Prenatal diagnostic procedures are medical tests which can be performed during the early part of pregnancy to detect certain birth defects. It is not possible to detect all birth defects prenatally.

Amniocentesis and chorionic villus sampling (CVS) are two prenatal diagnostic procedures currently available to detect specific birth defects. These procedures will be described, and the risks, benefits, and limitations of each will be presented to help you determine if you would like to have a prenatal diagnosis procedure. It is your choice whether or not to have a prenatal diagnostic procedure.

Summary of Prenatal Diagnostic Procedures

	Amniocentesis	CVS
Procedure	Amniotic fluid is removed by needle	Chorionic villi are removed by catheter (transcervical) or by needle (transabdominal), depending on location of placenta
Timing	15 - 20+ weeks. Early amnio is done between 14th and 15th week.	10 - 13+ weeks.
Accuracy of Chromosomal Analysis	Greater than 99% accuracy	Greater than 99% accuracy
Neural Tube Defects (NTDs)	AFP measured in amniotic fluid, with detection rate of 90 - 95%	Does not detect NTDs. Maternal AFP blood test offered between 15 and 20 weeks, with detection rate of 80 - 85%
Results	About 2 weeks	About 2 weeks
Miscarriage Due To Procedure	Less than 1 in 300. (Early amnio: less than 1 in 100)	Less than 1 in 100 (1%)
Vaginal Bleeding	Rare	Spotting may occur after transcervical CVS
Cramping	Occasional, usually mild	Occasional, usually mild
Infection, Fluid Leakage	Uncommon Fluid leakage may be slightly more common after early amniocentesis	Uncommon
Injury To Fetus	Extremely rare	Extremely rare
Frequency of Repeat Procedure	<1 in 300 (0.3%)	3-5%
Restriction of Activities	Limit physical activity for 24 hours after procedure (no sexual intercourse, strenuous exercise)	Limit physical activity for 24 hours after procedure (no sexual intercourse, strenuous exercise)

Program History

Please see our Regional Program history page for more information.

Condition Types

n/a