Peritonitis and Abdominal Sepsis Clinical Presentation

The diagnosis of peritonitis is usually clinical. History should include recent abdominal surgery, previous episodes of peritonitis, travel history, use of immunosuppressive agents, and the presence of diseases (eg, inflammatory bowel disease, diverticulitis, peptic ulcer disease) that may predispose to intra-abdominal infections.

A broad range of signs and symptoms are seen in spontaneous bacterial peritonitis (SBP). A high index of suspicion must be maintained when caring for patients with ascites, particularly those with acute clinical deterioration. As many as 30% of patients are completely asymptomatic. Manifestations of SBP may include the following:

• Fever and chills (as many as 80% of patients)
• Abdominal pain or discomfort (found in as many as 70% of patients)
• Worsening or unexplained encephalopathy
• Diarrhea
• Ascites that does not improve following administration of diuretic medication
• Worsening or new-onset renal failure
• Ileus

Abdominal pain, which may be acute or insidious, is the usual chief complaint of patients with peritonitis. Initially, the pain may be dull and poorly localized (visceral peritoneum); often, it progresses to steady, severe, and more localized pain (parietal peritoneum). Abdominal pain may be exacerbated by any movement (eg, coughing, flexing the hips) and local pressure. If the underlying process is not contained, the pain becomes diffuse. In certain disease entities (eg, gastric perforation, severe acute pancreatitis, intestinal ischemia), the abdominal pain may be generalized from the beginning.

Abdominal distention may be noted, as well as signs of dysfunction of other organs. Symptoms may be subtle in patients on corticosteroids, in diabetic patients with advanced neuropathy, and in hospitalized patients, especially the very young and the very old. In the presence of ascites, decreased friction between the visceral and parietal peritoneal surfaces may reduce the symptoms of abdominal pain, as seen in patients with SBP.

Anorexia and nausea are frequent symptoms and may precede the development of abdominal pain. Vomiting may be due to underlying visceral organ pathology (ie, obstruction) or be secondary to peritoneal irritation.

On physical examination, patients with peritonitis generally appear unwell and in acute distress. Many of them have a temperature that exceeds 38° C, although patients with severe sepsis may become hypothermic. Tachycardia may be present, as a result of the release of inflammatory mediators, intravascular hypovolemia from anorexia vomiting and fever, and third-space losses into the peritoneal cavity. With progressive dehydration, patients may become hypotensive (5-14% of patients), as well as oliguric or anuric; with severe peritonitis, they may present in overt septic shock.

When examining the abdomen of a patient with suspected peritonitis, the patient should be supine. A roll or pillows underneath the patient's knees may allow for better relaxation of the abdominal wall.

On abdominal examination, almost all patients demonstrate tenderness to palpation. In most patients—even those with generalized peritonitis and severe diffuse abdominal pain—the point of maximal tenderness or referred rebound tenderness roughly overlies the pathologic process (ie, the site of maximal peritoneal irritation).

Most patients demonstrate increased abdominal wall rigidity. The increase in abdominal wall muscular tone may be voluntary, in response to or in anticipation of the abdominal examination, or involuntary because of the peritoneal irritation. Patients with severe peritonitis often avoid all motion and keep their hips flexed to relieve the abdominal wall tension. The abdomen is often distended, with hypoactive-to-absent bowel sounds. This finding reflects a generalized ileus and may not be present if the infection is well localized. Occasionally, the abdominal examination reveals an inflammatory mass.

Signs of hepatic failure (eg, jaundice, angiomata) may be noted.

Rectal examination often elicits increased abdominal pain, particularly with inflammation of the pelvic organs, but rarely indicates a specific diagnosis. A tender inflammatory mass toward the right may indicate appendicitis, and anterior fullness and fluctuation may indicate a cul de sac abscess.

In female patients, vaginal and bimanual examination findings may be consistent with pelvic inflammatory disease (eg, endometritis, salpingo-oophoritis, tubo-ovarian abscess), but exam findings are often difficult to interpret in severe peritonitis.

A complete physical examination is important for excluding conditions whose presentation may resemble that of peritonitis. Thoracic processes with diaphragmatic irritation (eg, empyema), extraperitoneal processes (eg, pyelonephritis, cystitis, acute urinary retention), and abdominal wall processes (eg, infection, rectus hematoma) may mimic certain signs and symptoms of peritonitis. Always examine the patient for the presence of external hernias to rule out intestinal incarceration.

Remember that the presentation and the findings on clinical examination may be entirely inconclusive or unreliable in patients with significant immunosuppression (eg, severe diabetes, steroid use, posttransplant status, HIV infection), in patients with altered mental state (eg, head injury, toxic encephalopathy, septic shock, analgesic agents), in patients with paraplegia, and in patients of advanced age. With localized deep peritoneal infections, fever and/or an elevated WBC count may be the only signs present. As many as 20% of patients with SBP demonstrate very subtle signs and symptoms. New onset or deterioration of existing encephalopathy may be the only sign of the infection at the initial presentation. Most patients with TP demonstrate vague symptoms and may be afebrile.