Why is this procedure done?

Each human cell has 23 pairs of chromosomes. Inside of each chromosome are long, twisted units of genetic information. This is your DNA. Your chromosomes are made up of many tiny units called genes. Each person has a unique set of genes. Parents pass genes to their children.

Sometimes, you may have a problem with your genes. You may have too many chromosomes or a part of a chromosome may be missing. Each of these things may lead to a health problem.

Genetic testing looks at your genetic makeup. FISH genetic testing is short for fluorescence in situ hybridization. This kind of testing uses a fluorescent probe to check if there are extra or missing parts of genes or chromosomes.

The doctor may order a FISH genetic test to:

• Look for extra copies of a gene

• Find missing genes

• Learn if genes have been moved to a different place

• Look for extra or missing chromosomes

• Detect cancer in the cells

• Provide information about which drugs may be used to treat cancer

The decision to have a genetic test is a personal one. You may find you have many more questions after the test. Talk with your doctor about all possible outcomes of the test before having it.

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What will the results be?

• The doctor will look at the results of your test and what is normal. The doctor will know if you have an illness that needs treatment.

• If the results are normal, your chromosomes are likely normal in number and structure.

• If the results are not normal, you may have too many or too few chromosomes. They may also have a problem with one or more genes.

• Your doctor may order another test to verify the diagnosis.

• The doctor will talk with you about treatment.

What happens before the procedure?

• There are no special things to do before the test.

• Talk to your doctor about:

  • All the drugs you are taking

  • If you have any bleeding problems

  • Your family's medical history. You may want to talk with a genetic counselor.

What happens during the procedure?

If blood is used to run a FISH test, it will only take a few minutes to have this test. You will be awake the whole time. You will have a small amount of blood taken from you with a needle. You may have a small amount of pain. The needle will be taken out and a bandage will be put on your skin. The lab will test your blood to see your genes and chromosomes. Cells can also be tested from amniotic fluid, bone marrow, or tumor cells. The procedure for getting these cells is different.

What happens after the procedure?

• You may want to sit quietly for a few minutes before standing up. This will help keep you from feeling dizzy after the test.

• Put pressure with your other hand where the needle was. This will help with bruising and bleeding.

• Ask your doctor when you will get the results.

What care is needed at home?

You may do your everyday activities when you get back home.

What follow-up care is needed?

Your doctor may ask you to make visits to the office to talk about your results. Be sure to keep these visits. This test will help your doctor understand if you have a problem with your genes and chromosomes. Together you can make a plan for more care.

What problems could happen?

• Pain

• Bruising

• Bleeding

• Feeling dizzy

• Infection