Peritonitis

Peritonitis - an acute or chronic disorder - is an inflammation of the peritoneum, the membrane that lines the abdominal cavity and covers the visceral organs. Such inflammation may extend throughout the peritoneum or be localized as an abscess. Peritonitis commonly decreases intestinal motility and causes intestinal distention with gas. Mortality is about 10% ; bowel obstruction is the usual cause of death.

Causes

Peritonitis usually occurs as a complication of another abdominal disorder, for example if someone suffers a perforated appendix or if organ contents such as stomach acid leak into the abdominal cavity.

The most common cause is when bacterial infection spreads from somewhere else in the abdomen. For example, if the bowel perforates intestinal bacteria can escape into the abdominal cavity.

It may also occur when the peritoneum is irritated by organ contents, such as bile from an inflamed gall bladder, digestive enzymes from an inflamed pancreas, or stomach acid that escapes through a perforated stomach ulcer, that leak into the abdominal cavity.

Signs and Symptoms

The patient's symptoms depend on when the disorder is assessed, early or late in its course. In the early phase, the patient may report vague, generalized abdominal pain. If peritonitis is localized, he may describe pain over a specific area (usually over the site of inflammation); if the peritonitis is generalized, he may complain of diffuse pain over the abdomen.

As the disorder progresses, the patient typically reports increasingly severe and constant abdominal pain. Pain often increases with movement and respirations. Occasionally, pain may be referred to the shoulder or the thoracic area. Other signs and symptoms include abdominal distention, anorexia, nausea, vomiting, and an inability to pass stools and flatus.

Assessment of vital signs may reveal fever, tachycardia (a response to the fever), and hypotension. On inspection, the patient usually appears acutely distressed. He may lie very still in bed, often with his knees flexed to try to alleviate abdominal pain. He tends to breathe shallowly and move as little as possible to minimize pain. If he loses excessive fluid, electrolytes, and proteins into the abdominal cavity, you may observe excessive sweating, cold skin, pallor, abdominal distention, and signs of dehydration such as dry mucous membranes.

Early in peritonitis, auscultation usually discloses bowel sounds; as the inflammation progresses, these sounds tend to disappear. Abdominal rigidity is usually felt on palpation. If peritonitis spreads throughout the abdomen, palpation may disclose general tenderness; if peritonitis stays in a specific area, you may detect local tenderness. Rebound tenderness may also be present.

Diagnostic tests

The following tests support the diagnosis:

White blood cell count shows leukocytosis (commonly more than 20,000/1.11).

Abdominal X-rays demonstrate edematous and gaseous distention of the small and large bowel. With perforation of a visceral organ, the X-ray shows air in the abdominal cavity. Chest X-ray may reveal elevation of the diaphragm.

Paracentesis discloses the nature of the exudate and permits bacterial culture so appropriate antibiotic therapy can be instituted.

Treatment

To prevent peritonitis, early treatment of GI inflammatory conditions and preoperative and postoperative antibiotic therapy are important. After peritonitis develops, emergency treatment is instituted to combat infection, restore intestinal motility, and replace fluids and electrolytes.

Antibiotic therapy depends on the infecting organism but usually includes administration of cefoxitin with an aminoglycoside or penicillin G and clindamycin with an aminoglycoside. To decrease peristalsis and prevent perforation, the patient should receive nothing by mouth; instead, he requires supportive fluids and electrolytes parenterally.

Supplementary treatment includes administration of an analgesic such as meperidine, nasogastric (NG) intubation to decompress the bowel, and possible use of a rectal tube to facilitate the passage of flatus.

Surgery, the treatment of choice, eliminates the cause of peritonitis. As soon as the patient's condition is stable enough to tolerate surgery, the source of infection is eliminated by evacuating the spilled contents and inserting drains. The surgical procedure varies with the cause of peritonitis. For example, if appendicitis is the cause, an appendectomy is performed; if the colon is perforated, a colon resection may be performed. Occasionally, abdominalcavity may be necessary to remove accumulated fluid. Irrigation of the abdominal cavity with antibiotic solutions during surgery may be appropriate.

Prevention

Prevention depends on the cause. See the specific types of peritonitis.