Peritonitis

The peritoneum is the membrane that lines the abdominal cavity and covers organs.  When it becomes inflamed, the disease is called peritonitis.

This condition can be confused with intra-abdominal abscess (abdominal abscess), which involves a collection of pus in the abdomen that may cause peritonitis.  Before peritonitis develops, it can still cause symptoms that are similar or identical to peritonitis.

There are three main types of peritonitis: spontaneous, secondary, and peritonitis associated with dialysis.

Causes and Development

Also known as spontaneous bacterial peritonitis, spontaneous peritonitis is an infection that occurs as a complication of ascites (a collection of fluid in the peritoneal cavity).  Most cases of bacterial peritonitis occur as a result of ascites due to chronic liver disease, or in kidney failure patients undergoing peritoneal dialysis.  In the latter case, the cause of spontaneous peritonitis is infection in the blood that spreads to the peritoneal fluid, usually from a contaminated peritoneal dialysis catheter.

Risk factors for liver disease include alcoholic cirrhosis and other diseases that lead to cirrhosis, such as viral hepatitis.  Patients with kidney failure can develop nephrotic syndrome, which leads to ascites and can then become infected.

Secondary peritonitis is secondary to (caused by) another condition, most commonly the spread of an infection from the digestive organs or bowels.  Bacteria may enter the peritoneum via a hole in the gastrointestinal tract, which can be caused by a ruptured appendix, stomach ulcer or perforated colon.  The condition can also occur when pancreatic enzymes leak into the peritoneum during pancreatitis or when bile leaks from the biliary tract due to injury because these chemicals can irritate the peritoneum.  Foreign contaminants can also cause secondary peritonitis if they get into the peritoneal cavity.  This can occur during use of peritoneal dialysis catheters.

Peritonitis associated with dialysis (PAD) is an acute or chronic inflammation (irritation and swelling) of the peritoneum (lining of the abdominal cavity) that occurs in people receiving peritoneal dialysis.  The cause of dialysis-associated peritonitis may be the introduction of bacteria into the peritoneum by the dialysis procedure.  Skin bacteria are the most common organisms causing infection.  Incidence is about one infection for every 15 months of peritoneal dialysis.

Signs and Symptoms

(General) signs and symptoms include:

• Abdominal pain
• Abdominal tenderness
• Abdominal distention
• Fever
• Low urine output
• Nausea and vomiting
• Point tenderness
• Thirst
• Fluid in the abdomen
• Inability to pass feces or gas

Additional symptoms that may be associated with this disease include cloudy dialysis fluid (if undergoing peritoneal dialysis); nausea and vomiting; shaking chills; signs of shock.

Specific signs and symptoms of spontaneous peritonitis include: Fluid in the abdomen; abdominal pain and distention; tenderness; decreased bowel sounds; inability to pass feces or gas; fever; thirst; low urine output, nausea and vomiting, joint pain, chills.

Signs and symptoms of secondary peritonitis include: Abdominal pain; abdominal distention; fever; thirst; low urine output.  There may also be signs of shock.

Signs and symptoms of PAD include abdominal tenderness; distended abdomen; nausea and vomiting; cloudy dialysis fluid; fever; chills.

Diagnosis and Tests

Laboratory findings:

• Ascitic fluid – turbid, bloody, may contain fat globules; increased WBC; Gram's stain and aerobic and anaerobic cultures show multiple organisms; increased amylase; increased mononuclear cells and decreased glucose occur in tuberculous peritonitis
• Leukocytosis – up to 50,000/ul with 80-90% neutrophils; may not occur in older patients
• Increased hemoglobin, hematocrit, and BUN – reflect hemoconcentration secondary to extracellular fluid loss into the peritoneal cavity
• Laboratory findings of any of the underlying conditions.

Treatment and Prevention

Treatment of spontaneous peritonitis depends on the cause; surgery may be needed in cases where peritonitis is associated with a foreign object, such as a peritoneal dialysis catheter.  Antibiotics are administered to control infection in cases of spontaneous peritonitis in patients with liver or kidney disease, and dehydration is treated by intravenous therapy.  Hospitalization is common and may be necessary to rule out other causes of peritonitis such as appendicitis and diverticulitis.

Surgical treatment of secondary peritonitis is usually necessary to remove sources of infection such as infected bowel, inflamed appendix, or an abscess.  General treatment includes intravenous fluids, antibiotics, and use of medications to treat pain.

The goal of treatment in PAD cases is to cure the infection.  Antibiotics are given into a vein (intravenous injection) and/or into the peritoneum.  The antibiotic will be specific to the organism recovered in cultures of blood or peritoneal fluid.

Prognosis; Complications

The infection can usually be treated, but the prognosis for spontaneous peritonitis patients may be poor because of underlying kidney or liver disease.  People with these conditions often respond to antibiotics but may still have a poor outcome.

The outcome of secondary peritonitis depends on the underlying cause, the duration of symptoms before treatment, and the general health of the patient.  Outcomes can range from complete recovery to overwhelming infection and death, depending on these factors.

Most PAD patients recover completely.

Complications of spontaneous peritonitis may include abscess development; intestinal obstruction from scar tissue; hepatorenal syndrome; hepatic encephalopathy; massive sepsis (inflammation of peritoneal cavity caused by bacteria can result in infection of the bloodstream – sepsis – and severe illness.)

Possible complications of secondary peritonitis include septic shock, abscess or intraperitoneal adhesions.

PAD complications can include recurrent peritonitis, intra-abdominal abscess, catheter tract infection (removal of the dialysis catheter may be necessary.)