An abdominal tap is a procedure in which a needle is inserted through the abdominal wall to remove fluid from the abdomen. Normally, the abdomen contains only a small amount of fluid. In certain conditions, large amounts of fluid can accumulate in the abdomen.

There are two kinds of abdominal taps:

• Diagnostic tap -- a small amount of fluid is taken and sent to the laboratory for testing
• Large volume tap -- several liters may be removed to relieve abdominal pain and fluid buildup

This test may be done in an office setting, in a treatment room, or in a hospital.

The puncture site will be cleansed and shaved, if necessary. You then receive a local anesthetic. The tap needle is inserted 1 to 2 inches into the abdomen. Sometimes a small incision is made to help insert the needle. The fluid is then withdrawn into a syringe.

The needle is removed, and a dressing is applied to the puncture site. If an incision was made, one or two stitches may be used to close it.

Inform your health care provider if you have any allergies to medications or anesthetic, are taking any medications (including herbal remedies), have any bleeding problems, or might be pregnant.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experience, and level of trust. For general information regarding how you can prepare your child, see the following topics:

• Infant test/procedure preparation (birth to 1 year)
• Toddler test/procedure preparation (1 to 3 years)
• Preschooler test/procedure preparation (3 to 6 years)
• Schoolage test/procedure preparation (6 to 12 years)
• Adolescent test/procedure preparation (12 to 18 years)

You may feel a stinging sensation from the anesthetic or pressure as the needle is inserted.

If a large amount of fluid is withdrawn, you may experience dizziness or lightheadedness. Tell the health care provider if you feel dizzy.

An abdominal tap may be performed to diagnose the cause of fluid accumulation, to diagnose infected abdominal fluid, or to remove a large amount of fluid to reduce abdominal pain.

Normally, there should be little or no fluid in the abdomen.

An examination of abdominal fluid may reveal:

• Infection
• Tumor (cancerous or noncancerous)
• Appendicitis
• Cirrhosis of the liver
• Pancreatic disease
• Kidney disease
• Heart disease
• Damaged bowel

There is a slight chance of the needle puncturing the bowel, bladder, or a blood vessel in the abdomen. If a large quantity of fluid is removed, there is a slight risk of lowered blood pressure. There is also a slight chance of infection.