Paracentesis

March 25, 2026

This page was reviewed under our medical and editorial policy by Barbara Buttin, M.D., gynecologic oncologist and associate clinical professor, Department of Surgery, City of Hope^® Cancer Center Chicago.

Paracentesis, also called abdominal tapping, is a procedure used to drain excess fluid from the abdominal cavity, which is the space between the abdominal wall and the spine. Doctors perform paracentesis to alleviate symptoms such as bloating, abdominal pain or pressure, large or growing belly and shortness of breath caused by fluid accumulation.

What Is Paracentesis?

Doctors use paracentesis to diagnose the cause of excess fluid, also called ascites, in the abdomen, and also to treat the symptoms caused by fluid buildup.

The most common cause of ascites is cirrhosis, or permanent scarring of the liver. Other conditions may also lead to excess fluid in the abdominal cavity, including portal hypertension, or high blood pressure in the liver’s main vein; fluid infection; abdominal injury; liver and heart failure; and cancer.

What Types of Cancer Cause Fluid in the Abdomen?

During paracentesis, fluid is collected and analyzed to help determine the cause of abdominal ascites. If cancer cells are present in the ascitic fluid, the patient has malignant ascites.

The following cancers most commonly cause abdominal ascites:

• Bladder cancer
• Breast cancer
• Colon cancer
• Liver cancer
• Lung cancer
• Ovarian cancer
• Pancreatic cancer
• Stomach cancer
• Uterine cancer

Paracentesis Versus Thoracentesis

Paracentesis involves removing fluid from the abdominal cavity, while thoracentesis involves removing fluid from the chest cavity. The procedures share some similarities, but are typically used to diagnose and treat different conditions.

Preparation

Before patients undergo paracentesis, the care team reviews their medical history, gives them a physical exam and orders other lab tests. The team will also advise patients about medicines and supplements to take or stop taking, and may recommend that they stop drinking liquids or eating certain foods a few hours or the night before the procedure.

Paracentesis Procedure Steps

Paracentesis is typically performed in a doctor’s office, outpatient clinic or hospital. It can take between 20 to 45 minutes, depending on how much fluid is removed.

Once the patient is ready with an empty bladder, the care team performs the procedure using the following steps.

Step 1: The patient lies flat on his or her back on a bed that is flat or slightly raised.

Step 2: The care team numbs the area (with a local anesthetic) where the needle or catheter will go.

Step 3: The care team inserts a thin, hollow needle or a catheter into the skin and muscles into the abdominal cavity. Sometimes, doctors use an ultrasound to help pinpoint where to put the needle.

Step 4: The care team extracts excess fluid with a syringe or vacuum-powered container.

Step 5: The care team removes the needle or catheter and covers the insertion area with a bandage.

Recovery

Following the procedure, the care team monitors the patient’s vital signs for about an hour, then discharges the patient with home care instructions. Resting for 24 hours after paracentesis is recommended.

It’s normal to see small amounts of fluid seeping from the drainage site for a day or two.

Patients are urged to follow the care team’s guidance on when it’s safe to resume eating, drinking and physical activities, especially if the patient received stitches.

Paracentesis Complications

Though rare, side effects of paracentesis include:

• Discomfort or pain at the wound site
• Dizziness
• Infection
• Needle puncturing the bowel, bladder or blood vessels
• Ongoing fluid leakage at the wound site
• Low blood pressure
• Internal bleeding or a blood clot that forms under the skin

Patients should contact the care team immediately if any signs of a complication are present, including:

• Fever and chills
• Bleeding or fluid leakage from the wound site
• Tenderness or redness at the wound site
• Foul-smelling drainage or pus
• Chest pain
• Severe pain or increased abdominal swelling
• Shortness of breath
• Light-headedness or fainting

Results

After paracentesis, the doctor may discuss the results with the patient to help identify the cause of fluid accumulation and recommend further tests, treatments or follow-up care.

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

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

The care team may also recommend chemotherapy, hormone therapy, surgery, diet modifications or the use of diuretics, sometimes called water pills.