This page was reviewed under our medical and editorial policy by

Chukwuemeka Obiora, MD, Surgical Oncologist

This page was reviewed on April 7, 2023.

Paracentesis is a procedure used to remove excess fluid, or ascites, from the abdominal area. If you have cancer, ascites may develop because of pressure from tumors, causing discomfort.

You may need a paracentesis for advanced cancer, particularly if you have any of the following types:

A paracentesis is also called an abdominal tap or peritoneal tap.

Four ways to prepare for a paracentesis

A paracentesis doesn’t typically require a lot of preparation, but there are several steps you may wish to complete before the procedure.

  1. Inform your care team of any and all medications that you use. These include over-the-counter drugs and herbal supplements as well as topical creams and patches. If you use blood-thinning medications such as aspirin or anticoagulants, your doctor may ask you to stop taking them for a couple of days before your paracentesis.
  2. Also, be sure to communicate any allergies to medicines.
  3. Ask whether you will need an ultrasound before the paracentesis and make sure to get it done with ample time. Some doctors perform an ultrasound in advance to help guide how and where they perform the procedure.
  4. Check whether you may eat and drink normally before the procedure or if you have any limitations. You may be asked to avoid eating and drinking up to 12 hours before a scheduled paracentesis.

What to expect from a paracentesis

Doctors typically perform a paracentesis in a hospital, outpatient clinic or their office. The procedure takes about 45 minutes.

For the procedure, you lie down in a bed with your head raised. Your abdomen area is exposed and cleaned, and a numbing medicine is applied. (The medicine may cause you to feel some stinging.) Next, a needle is inserted about an inch or two into the abdomen. The doctor may need to make a small cut to help with needle insertion.

The doctor then removes fluid with a syringe. It’s normal to feel lightheaded if the doctor is removing a lot of fluid, but let your care team know if you experience this feeling.

When the procedure is over, the incision site is bandaged. If a cut was made, the doctor may close it with one or two stitches. Then:

  • You rest briefly after having the procedure.
  • If you feel discomfort, ask your doctor about taking an over-the-counter pain reliever. You may also experience some fluid leakage at the procedure site for the first 24 hours. Be sure to call your doctor if this leaking persists.
  • Your doctor or nurse should let you know when you can shower after a paracentesis. Usually, it’s 24 hours later. You should be able to resume normal activities after the procedure.

Benefits and risks of a paracentesis

The benefit of a paracentesis is that it provides relief from any discomfort caused by ascites. However, it’s common for the fluid to return. You may need to have the procedure repeated in a few weeks, or have a special tube called a catheter placed so fluid can continuously drain out.

While a paracentesis for someone with cancer usually focuses on providing relief from fluid buildup, doctors also may choose to analyze the fluid. In this case, the fluid is sent to a laboratory to try to identify a cause for the buildup. Finding a cause is important because it could be related to an advancing cancer, heart disease, infection or other condition.

Although the risks of a paracentesis are low, they are still a possibility. Risks associated with a paracentesis include:

  • Infection (alert your care team if you have a fever of 100.4°F or higher after the procedure, redness at the puncture site, or abdominal pain that increases)
  • Kidney damage
  • Low blood pressure
  • Puncturing of the bladder, blood vessels or bowel during the procedure

Reviewing the results of a paracentesis

If you underwent a paracentesis to remove uncomfortable excess fluid related to a previously diagnosed cancer, your doctor may suggest additional ways to control the fluid and prevent it from building up again.

One way is by placing a catheter inside your body that attaches to a receptacle outside the body, allowing the fluid to drain without you having to return for another paracentesis.

Your doctor may also recommend chemotherapy, surgery, changes to your diet or the use of a diuretic.

If the doctor used a paracentesis to find out the cause of your excess fluid buildup, then the results may help show which other treatments, if any, you may need. Make sure to ask your care team any questions that you have along the way.

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