The clinical picture of peritonitis is determined by the nature of the causative lesion, duration and extension of the inflammatory process, and stage of the disease. The main manifestations of peritonitis are acute abdominal pain, tenderness, and guarding, which are exacerbated by moving the peritoneum, e.g. coughing, flexing the hips, or eliciting the Blumberg sign (a.k.a. rebound tenderness, meaning that pressing a hand on the abdomen elicits pain, but releasing the hand abruptly will aggravate the pain, as the peritoneum snaps back into place).

Thorough history usually points toward the cause of peritonitis in addition to the risk factors ( Recent abdominal surgery, diverticulitis, peptic ulcer disease, etc).

Common symptoms of secondary peritonitis include:^[1]

• Abdominal pain: Abdominal pain is the hallmark of peritonitis. The pain can be:
  • Generalized to the whole abdomen: Diffuse abdominal pain occurs with GI perforations or due to irritation of the visceral peritoneum early in the course of localized GI inflammation (appendicitis, diverticulitis, etc)
  • Localized: due to irritation of the parietal peritoneum late in the course of localized GI inflammation (appendicitis, diverticulitis, etc)

• Worsening of pre-existing ascites and progressive encephalopathy in a patient with cirrhotic ascites

• Altered mental status may manifest as frank delirium, confusion or cognitive slowing.

• Diarrhea

• Development of ileus paralyticus

• Nausea and vomiting can be due to peritoneal irritation or due to the underlying cause (appendicitis, peptic ulcer, etc)

• Bloating

• Anorexia

• Obstipation

• Low urine output

• Thirst

• Fatigue

• Chills

• Dizziness or weakness

• Breathlessness may be due to infection, fluid overload or underlying heart condition