A paracentesis is a procedure that uses a hollow needle or plastic tube (catheter) to remove fluid from the abdominal cavity. A paracentesis may also be called an abdominal tap.

Why a paracentesis is done

A paracentesis is done when a person has a swollen abdomen, pain or problems breathing because there is too much fluid in the abdomen (ascites). Normally, there is little or no fluid in the abdomen. Removing the fluid helps relieve these symptoms. The fluid may be examined to help find out what is causing the ascites.

How a paracentesis is done

A paracentesis is done in an outpatient clinic or in a hospital. Depending on the amount of fluid that needs to be removed, a paracentesis can take up to 45 minutes.

You will lie on your back on a bed that has the head slightly raised. You won’t have anything covering your abdomen. A local anesthetic is used to numb the area where the doctor will put in the hollow needle.

The doctor will use a thin, hollow needle or a catheter. The needle or catheter is pushed through the skin and muscles into the abdominal cavity. Sometimes an ultrasound is done to help the doctor find the best place to put the needle.

Once the needle or catheter is in place, the excess fluid is drained. When fluid stops draining, the needle or catheter is removed. A small bandage is used to cover the area where the needle or catheter was inserted.

If your healthcare team thinks that fluid will build up again, they may put a permanent tube in place. This is called a tunnelled peritoneal drainage catheter. One end of this catheter stays inside the body, and the other end is attached to a bottle or container outside the body. You can drain the fluid at home and won’t have to keep going back to the hospital.

Potential side effects

A paracentesis doesn’t usually cause many side effects. Some side effects may include:

  • discomfort or pain where the needle or catheter is inserted
  • dizziness or light-headedness, especially if a lot of fluid is removed
  • infection
  • puncture of the bowel, bladder or blood vessels when the needle is put into the cavity
  • low blood pressure or shock
  • kidney failure

What the results mean

There are several causes of too much fluid in the abdomen, including:

  • injury to the abdomen
  • infection of the peritoneum (peritonitis)
  • scarring of the liver tissue (cirrhosis) or liver failure
  • cancer, in particular ovarian, uterine, cervical, colorectal, stomach, pancreatic or liver cancer

What happens if the result is abnormal

Depending on the results, your doctor will decide if you need more tests, any treatment or follow-up care.

Special considerations for children

Preparing children before a test or procedure can lower anxiety, increase cooperation and help them develop coping skills. Parents and caregivers can help prepare children by explaining to them what will happen, including what they will see, feel, hear, taste or smell during the test.

Preparing a child for a paracentesis depends on the age and experience of the child. Find out more about helping your child cope with tests and treatments.

Expert review and references

  • OneCare Media . Peritoneal fluid analysis . Seattle, WA : 2014 :
  • Cope DG . Malignant effusions. Yarbro, CH, Wujcki D, & Holmes Gobel B. (eds.). Cancer Nursing: Principles and Practice. 7th ed. Sudbury, MA: Jones and Bartlett; 2011: 35: pp. 863-878.
  • Shlamovitz GZ . Medscape Reference: Paracentesis . 2015 :
  • Slusser K . Malignant ascites. Yarbro CH, Wujcik D, Holmes GB (eds.). Cancer Symptom Management. 4th ed. Jones & Bartlett Learning; 2014: 12: 241-262.
  • US National Library of Medicine . MedlinePlus Medical Encyclopedia: Abdominal tap . Bethesda, MD : US Department of Health and Human Services ; 2016 :

Medical disclaimer

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