Landspitali - University Hospital
Prenatal diagnosis 22B
Table of contents
Prenatal diagnosis – chorionic villus sampling (CVS) and amniocentesis
Prenatal diagnostic testing can identify certain chromosomal abnormalities or genetic conditions in a baby before birth. It may be offered when screening results or other information indicate that further testing is needed.
A sample is taken from the placenta or amniotic fluid using a fine needle inserted through the pregnant woman's abdomen. These procedures carry a small risk of miscarriage, approximately 0.2–0.5%.
Chorionic villus sampling (CVS) – a small sample of tissue is taken from the placenta.
Amniocentesis – a small amount of amniotic fluid is taken for testing.
What tests are performed on the sample?
Different methods can be used to analyse the baby's genetic material, depending on what is being investigated. Some tests can detect changes in the number of chromosomes, while others can identify smaller changes in chromosomes or individual genes.
A midwife or doctor can explain which tests may be appropriate, what they can detect and their limitations.
Results are usually available within a few days to several weeks, depending on the type of test.
After the procedure
Mild abdominal cramps, similar to period pain, may occur after chorionic villus sampling (CVS) or amniocentesis. These usually settle within one to two days. Resting for the remainder of the day is recommended.
If there is any vaginal bleeding, leakage of amniotic fluid, fever, or severe or persistent abdominal pain, medical advice should be sought.
If there is a genetic condition in the family
If there is a known genetic condition or inherited syndrome in either parent's family, targeted prenatal diagnostic testing may be considered.
The Department of Genetics and Molecular Medicine at Landspítali can be contacted, and a request can be submitted through the Landspítali app. Following an assessment, an appointment is usually offered to discuss the available tests and their limitations.
Further information
No test can detect all genetic conditions in a baby. A midwife or doctor can explain which tests may be appropriate and what the results can and cannot tell us.
For more detailed information about the tests, results and their limitations, see the leaflet Prenatal genetic testing – non-invasive prenatal testing (NIPT) and prenatal diagnostic testing (in Icelandic).