Health Encyclopedia - Test
An abdominal tap is a procedure used to remove fluid from the area between the belly wall and the spine. This space is called the abdominal cavity.
Peritoneal tap; Paracentesis
How the test is performed
This test may be done in an office setting, treatment room, or hospital.
The puncture site will be cleaned and shaved, if necessary. You then receive a local numbing medicine. The tap needle is inserted 1 - 2 inches into the abdomen. Sometimes a small cut is made to help insert the needle. The fluid is pulled out into a syringe.
The needle is removed. A dressing is placed on the puncture site. If a cut was made, one or two stitches may be used to close it.
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
How to prepare for the test
Let your health care provider know if you:
- Have any allergies to medications or numbing medicine
- Are taking any medications (including herbal remedies)
- Have any bleeding problems
- Might be pregnant
How the test will feel
You may feel a stinging sensation from the numbing medicine, or pressure as the needle is inserted.
If a large amount of fluid is taken out, you may feel dizzy or light-headed. Tell the health care provider if you feel dizzy.
Why the test is performed
Normally, the abdominal cavity contains only a small amount of fluid. In certain conditions, large amounts of fluid can build up in this space.
An abdominal tap can help diagnose the cause of fluid buildup. It may also be done to diagnose infected abdominal fluid, or to remove a large amount of fluid to reduce belly pain.
Normally, there should be little or no fluid in the abdominal space.
What abnormal results mean
An examination of abdominal fluid may show:
What the risks are
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 and kidney failure. There is also a slight chance of infection.
Garcia-Tiso G. Cirrhosis and its sequelae. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 156.
Runyon BA. Ascites and spontaneous bacterial peritonitis. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 91.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.