Abdominal tap

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.

Normal Results

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

What Abnormal Results Mean

An examination of abdominal fluid may show:

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

Risks

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.

Alternative Names

Peritoneal tap; Paracentesis

References

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.

Update Date: 8/10/2012

Updated 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.