Cytogenetic Testing: Fluorescent In Situ Hybridization (FISH) Testing

Also known as: FISH testing, congenital blood test, cytogenetic testing.

What is cytogenetic testing: fluorescent in situ hybridization testing?

The FISH (fluorescent in situ hybridization) test is a blood test that “maps” the genetic material (passed from parent to child during maternal fertilization) in a child’s cells looking particularly for gene abnormalities which can give rise to developmental delays, autism, mental retardation and other rare genetic disorders that sometimes occur at birth.

What happens during the procedure?

A small amount of blood is drawn in the usual way from a child’s vein and sent to a Genetics laboratory for testing.

Is any special preparation needed?

No special preparation is needed for this test.

What are the risk factors?

There are slight risks of infection, bleeding, bruising, swelling or damage to nearby structures when the blood is drawn.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: 11/9/2018 9:51:16 AM

From the Newsdesk

What is the Personalized Medicine Biobank?
The Nicklaus Children's Hospital biobank and tissue repository is an essential resource for personalized medicine research efforts, enabling the study of both health and disease over time. The Biobank collects samples and health information from volunteers, regardless of health history. Once a participant becomes part of the Biobank, he or she contributes to ongoing health research. We partner with Sanford Health, a national leader on specimen storage, management and integration with participant health information.
What is Genetic Testing?
Dr. Parul Jayakar discusses genetic testing for family planning. Learn more at