paracentesis

Heartburn & GERD Is it heartburn or GERD? Learn the difference.

More about Paracentesis: Purpose Aftercare Risks Normal results Abnormal results Resources

Definition

Paracentesis is a procedure during which fluid from the abdomen is removed through a needle.

Description

During paracentesis, special needles puncture the abdominal wall, being careful not to hit internal organs. If fluid is needed only for analysis, just a bit is removed. If pressure relief is an additional goal, many quarts may be removed. Rapid removal of large amounts of fluid can cause blood pressure to drop suddenly. For this reason, the physician will often leave a tube in place so that fluid can be removed slowly, giving the circulation time to adapt.

A related procedure called culpocentesis removes ascitic fluid from the very bottom of the abdominal cavity through the back of the vagina. This is used mostly to diagnose female genital disorders like ectopic pregnancy that bleed or exude fluid into the peritoneal space.

Fluid is sent to the laboratory for testing, where cancer and blood cells can be detected, infections identified, and chemical analysis can direct further investigations.

— J. Ricker Polsdorfer, MD

[L., fr. Gr. parake`nthsis, fr. parakentei^n to pierce at the side, to tap.]
(Med.) The perforation of a cavity of the body with a trocar, aspirator, or other suitable instrument, for the evacuation of effused fluid, pus, or gas; tapping.

Definition

Paracentesis is a minimally invasive procedure using a needle to remove fluid from the abdomen.

Purpose

There are two reasons to take fluid out of the abdomen. One is to analyze it for diagnostic purposes; the other is to relieve pressure. Liquid that accumulates in the abdomen is called ascites. Ascites seeps out of organs for several reasons related either to disease in the organ or fluid pressures that are changing.

Liver Disease

All the blood flowing through the intestines passes through the liver on its way back to the heart. When progressive disease such as alcohol damage or hepatitis destroys enough liver tissue, the scarring that results shrinks the liver and constricts blood flow. Such scarring of the liver is called cirrhosis. Pressure builds in the intestinal blood circulation, slowing flow and pushing fluid into the surrounding tissues. Slowly the fluid accumulates in areas with the lowest pressure and greatest capacity. The free space around abdominal organs receives the greatest amount. This space is called the peritoneal space because it is enclosed by a thin membrane called the peritoneum. The peritoneum wraps around nearly every organ in the abdomen, providing many folds and spaces for the fluid to gather.

Infections

Peritonitis is an infection of the peritoneum that can develop in several ways. Many abdominal organs contain germs that do not occur elsewhere in the body. If they spill their contents into the peritoneum, infection is the result. Infection changes the dynamics of body fluids, causing them to seep into tissues and spaces. The gall bladder, the stomach, any part of the intestine, and most especially the appendix—all cause peritonitis when they leak or rupture. Tuberculosis can infect many organs in the body; it is not confined to the lungs. Tuberculous peritonitis causes ascites.

Other Inflammations

Peritoneal fluid is not just produced by infections. An inflamed pancreas, called pancreatitis, can cause a massive sterile peritonitis when it leaks its digestive enzymes into the abdomen.

Cancer

Any cancer that begins in or spreads to the abdomen can leak fluid. One particular tumor of the ovary that leaks fluid and results in fluid accumulation is called
Meigs' syndrome.

Kidney Disease

Since the kidneys are intimately involved with the body's fluid balance, diseases of the kidney often cause excessive fluid to accumulate. Nephrosis and nephrotic syndrome are the general terms for diseases that cause the kidneys to retain water and promote its movement into body tissues and spaces.

Heart Failure

The ultimate source of fluid pressure in the body is the heart, whose pumping generates blood pressure. All other pressures in the body are related to blood pressure. As the heart starts to fail, blood backs up, waiting to be pumped. This increases pressure in the veins leading to the heart, particularly below it where gravity is also pulling blood down. The extra fluid from heart failure is first noticed in the feet and ankles, where gravitational effects are most evident. In the abdomen, the liver swells first, then it and other abdominal organs start to leak.

Pleural Fluid

The other major body cavity (besides the abdomen) is the chest. The tissue in the chest corresponding to the peritoneum is called the pleura, and the space contained within the pleura, between the ribs and the lungs, is called the pleural space. Fluid is often found in both cavities, and fluid from one cavity can find its way into the other.

Fluid that accumulates in the abdomen creates abnormal pressures on organs in the abdomen. Digestion is hindered; blood flow is slowed. Pressure upward on the chest from fluid-filled organs compromises breathing. The kidneys function poorly in the presence of such external pressures and may even fail.

Description

During paracentesis, special needles puncture the abdominal wall, being careful not to hit internal organs. If fluid is needed only for analysis, less than 7 oz (200 ml) are removed. If pressure relief is an additional goal, many quarts may be removed. Rapid removal of large amounts of fluid can cause blood pressure to drop suddenly. For this reason, the physician will often leave a tube in place so that fluid can be removed slowly, giving the system time to adapt.

A related procedure called culpocentesis removes ascitic fluid from the very bottom of the abdominal cavity through the back of the vagina. This is used most often to diagnose female genital disorders like ectopic pregnancy, which may bleed or exude fluid into the peritoneal space.

Fluid is sent to the laboratory for testing, where cancer and blood cells can be detected, infections identified, and chemical analysis can direct further investigations.

Aftercare

An adhesive bandage and perhaps a single stitch close the insertion site. Nothing more is required.

Risks

Risks are negligible. It is remotely possible that an organ could be punctured and bleed or that an infection could be introduced.

Normal Results

A diagnosis of the cause and/or relief from accumulated fluid pressure are the expected results. Fluid will continue to accumulate until the cause is corrected. Repeat procedures may be needed.

Resources

Books

Chung, Raymond T. and Daniel K. Podolsky. "Cirrhosis and its Complications." In Harrison's Principles of Internal Medicine, edited by Eugene Braunwald, et al. New York: McGraw-Hill, 2001.

Henry, J. B. Clinical Diagnosis and Management by Laboratory Methods. 20th ed. Philadelphia, PA: W. B. Saunders Company, 2001.

Other

Lehrer, Jennifer K. Abdominal tap—paracentesis. National Institutes of Health. January 1, 2003 [cited April 4, 2003]. http://www.nlm.nih.gov/medlineplus/encyclopedia.html.

"Paracentesis." American Thoracic Society. April, 2003 [cited April 4, 2003]. http://www.thoracic.org/assemblies/cc/ccprimer/infosheet10.html.

— J. Ricker Polsdorfer, MD Mark A. Best, MD

Key Terms: Appendicitis, Cirrhosis.

Definition

Also known as peritoneal tap or abdominal tap, paracentesis consists of drawing fluid from the abdomen through a needle.

Purpose

Although little or no fluid is present in the abdominal (peritoneal) cavity of a healthy man, more than half an ounce may accumulate at certain times during a woman's menstrual cycle. Any cancer that originates in or spreads to the abdomen can result in fluid accumulation (malignant ascites).

Doctors remove fluid (ascites) from the abdomen to analyze its composition and determine its origin, to relieve the pressure and discomfort it causes, and to check for signs of internal bleeding This procedure should be performed whenever an individual experiences sudden or worsening abdominal swelling or when ascites is accompanied by fever, abdominal pain, confusion, or coma.

Paracentesis in Cancer Patients

When performed on a patient who has been diagnosed with cancer, paracentesis helps doctors determine the extent (stage) of the disease and whether conservative or radical treatment approaches would most effectively relieve symptoms or lengthen survival.

Precautions

Before undergoing paracentesis, a patient must make the doctor aware of any allergies, bleeding problems or use of anticoagulants, pregnancy, or possibility of pregnancy.

Description

Paracentesis is performed in a doctor's office or a hospital. The puncture site is cleansed and, if necessary, shaved. The patient may feel some stinging as a local anesthetic is administered, and pressure as the doctor inserts a special needle (tap needle) into the abdomen. Occasionally, guidance with CT or ultrasound may be used.

When paracentesis is performed for diagnostic purposes, less than an ounce of fluid is drawn from the patient's abdomen into a syringe. As much as 15 ounces may be needed to determine whether ascites contains cancer cells. When the purpose of the procedure is to relieve pressure or other symptoms, many quarts of ascites may be drained from the abdomen. Because removing large amounts of fluid in a short time can cause dizziness, lightheadedness, and a sudden drop in blood pressure, the doctor may drain fluid slowly enough that the patient's circulatory system has time to adapt.

Laboratory analysis of abdominal fluid can detect blood, cancer cells, infection, and elevated protein levels often associated with malignant ascites. Results of these tests can help doctors determine the most appropriate course of treatment for a particular patient.

Preparation

No special preparations are required before this procedure. Patients should ask their doctors about special preparation requirements, but usually may eat, drink and take medications normally prior to paracentesis.

Aftercare

After removing the tap needle, the doctor may use a stitch or two to close any incision made (to ease the needle's entry into the abdomen) and applies an adhesive dressing to the puncture site.

Risks

Paracentesis occasionally causes infection. There is also a slight chance of the tap needle puncturing the bladder, bowel, or blood vessels in the abdomen. If large amounts of ascites are removed, the patient may need to be hospitalized and given intravenous (IV) fluids to prevent or correct severe fluid, protein, or electrolyte imbalances. A patient who has undergone extensive paracentesis should be warned about the possibility of fainting (syncope) episodes.

Normal Results

Paracentesis is designed to establish the cause of, or to relieve symptoms associated with, an abnormal accumulation of fluid in the abdomen.

Abnormal Results

Laboratory tests of ascites may indicate the presence of:

• appendicitis
• cancer
• cirrhosis
• damaged bowel
• disease of the heart, kidneys, or pancreas
• infection

Ascites that contains cancer cells is usually bloody. Cloudy abdominal fluid has been found in patients with extensive intraabdominal lymphomas. Ascites will continue to accumulate until its cause is identified and eliminated. Some patients need to undergo paracentesis repeatedly.

Resources

Books

Tierney, Lawrence J., et al., editors. Current Medical Diagnosis & Treatment 2000. New York: Lange Medical Books/McGraw-Hill, 2000.

—Maureen Haggerty

Surgical puncture of a cavity for the aspiration of fluid.

• abdominal p. — insertion of a trocar through a small incision or a needle into the abdominal cavity, to remove ascitic fluids, inject a therapeutic agent, or to collect a sample for cytological and chemical examination. It is an important technique in the examination of horses for colic and in investigation of causes of ascites in all species. Called also abdominocentesis.
• anterior chamber p. — aspiration of aqueous humor from the anterior chamber may be indicated as a diagnostic procedure in diseases such as hypopyon, hyphemia, glaucoma and iridocyclitis.
• pericardial p. — see pericardicentesis.
• thoracic p. — surgical puncture for drainage of the thoracic cavity and for collection of a sample of fluid for clinical pathology examination See also thoracentesis.
• vitreous p. — may be useful in the diagnosis of diseases of the posterior segment of the eye, e.g. endophthalmitis, panophthalmitis and neoplasms. Called also hyalocentesis.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)