5 Min Read
Last Updated: 02/02/2024
Fact Checked

Written by Karen Selby, RN | Medically Reviewed By Dr. Daniel Landau | Edited By Walter Pacheco

What Is a Paracentesis?

Paracentesis, sometimes called an abdominal tap or ascites tap, is a type of minor surgery. A doctor uses a hollow needle to take away extra fluid from the patient’s belly.

The inside of your abdomen has a lining that separates the organs from the abdominal wall. There is a small amount of liquid between these two layers. When more than an ounce (30 ml) of fluid develops in the peritoneal cavity, it is called ascites or ascitic fluid.

When too much ascitic fluid builds up in the peritoneal space, it can put pressure on the abdominal organs and the diaphragm. This accumulation of ascitic fluid can be caused by infection, injury, liver damage or cancer. Ascites is commonly found in cases of peritoneal mesothelioma.

If the purpose is only to diagnose the cause of the ascites, a doctor may take as little as 50 mL of fluid for analysis. For a therapeutic paracentesis, a doctor may drain a liter of fluid or more.

A 2021 research report said a paracentesis may also help improve the clarity of radiological imaging.

Quick Facts About Paracentesis

  • Drains excess fluid from abdominal lining
  • Usually performed as out-patient procedure
  • Temporarily treats abdominal symptoms
  • Less invasive than other surgical treatments

Ascites often develops in people with peritoneal mesothelioma. That’s because widespread abdominal tumors can cause a condition known as peritoneal carcinomatosis. Tumors can damage the linings of the abdomen and block how fluid flows in and out. They also weaken cells in the abdominal wall which stops protein and fat from leaking out of blood vessels into the abdomen.

Ascites Drainage Diagram
Diagram of Ascites Drainage

Paracentesis can help ease the signs of peritoneal mesothelioma, but it is not a good way to tell if someone has this uncommon type of cancer.

Even when someone does have cancer, the cells in their ascitic fluid may look normal. This is why doctors need to take out some tissue and examine it closely (called a biopsy) instead of only looking at the cells from the drained fluid.

Palliative Paracentesis Benefits and Alternatives

Paracentesis is a simple procedure that doesn’t require you to stay in the hospital. It can help make people with cancer feel better and improve their quality of life, no matter what stage they’re at.

Its main limitation is that it is a palliative treatment, and it does not prevent the patient from developing ascites again in the future.

Many peritoneal mesothelioma patients have a high rate of ascites recurrence. Rather than repeating it, doctors prefer to leave a catheter in place to continuously drain the peritoneal cavity.

If tumor development causes the fluid to become loculated, a paracentesis will be less effective. Loculated means the fluid builds up in smaller spaces in the abdomen and does not flow freely in the peritoneal cavity.

Surgery with heated chemotherapy has revolutionized the treatment of peritoneal mesothelioma. A 2016 review noted HIPEC successfully controls ascites in more than 90% of patients.

Surgical Consultation for Paracentesis

If you think paracentesis might be a good option for your mesothelioma, you can meet with the surgeon and their team to learn more about it. During a consultation, you will meet with the surgeon and members of the surgical team.

They will take a look at your medical history to see if this procedure is suitable for you. During the appointment, they’ll also answer any questions or worries that you have about paracentesis.

The surgical team will review everything you need to know to prepare for and recover from a paracentesis. These consultations are an important part of vetting patients for surgery. They also help patients prepare for the procedure. They may be conducted in person or virtually through video conferencing.

The Paracentesis Procedure

Paracentesis is often performed as an outpatient procedure, taking approximately 20 to 30 minutes. In many cases, an ultrasound is first administered to better visualize the size and scope of the ascitic fluid buildup.

After making sure their bladder is empty, the patient lays on a bed elevated at a 45-degree angle to allow fluid to accumulate in their lower abdomen. The doctor cleans the insertion site with antiseptic and numbs it with a local anesthetic before inserting a large-bore needle to reach the peritoneal cavity.

Once the ascitic fluid begins to flow, the cavity is drained either by gravity, a syringe or connection to a vacuum bottle. Doctors typically drain only one liter of fluid at a time, no faster than 500 mL every 10 minutes, so the body can equilibrate fluids and electrolytes. If several liters of fluid are drained during the procedure, the patient may receive serum albumin to replace lost fluid, prevent a drop in blood pressure and reduce the risk of shock.

After the desired level of drainage is complete, the doctor covers the insertion site with a sterile dressing and a small suture, if necessary. Alternatively, if the procedure is going to be repeated, a catheter with a flow-control valve and protective dressing can be left in place.

The patient is usually discharged within a few hours, provided their blood pressure is normal and they have no feeling of dizziness.

Risks and Complications

A paracentesis is a fairly simple procedure that presents very few risks. Rare complications include:

  • Infection
  • Persistent leak from the insertion site
  • Abdominal wall hematoma (collection of blood outside a blood vessel)
  • Perforation of the small or large intestine, stomach or bladder
  • Hypotension (low blood pressure)

One documented complication that occurred in a patient with peritoneal mesothelioma was the repeated occurrence of a pneumothorax after a paracentesis procedure. A pneumothorax occurs when air builds up in the space around the lungs and doesn’t allow the lung to expand fully. This is a rare complication, but doctors feel it should be considered in patients with pre-existing pulmonary disease.

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