In most cases, an inflammatory process is confined to the colon and its mesentery and adjacent structures or peritoneal surfaces. In the patient with diverticular perforation, a pericolic or pelvic abscess may be present with associated high fever. Patients with perforation and diffuse peritonitis usually present with severe generalized abdominal pain and associated paralytic ileus. Diffuse peritonitis may lead to septic shock with prostration and cardiovascular collapse. High-grade colonic obstruction manifests as colicky abdominal pain, bloating and constipation or obstipation.
Abdominal findings reflect the severity and localization of the septic process.
The inflamed colon or pericolic abscess causes marked localized tenderness with or without a palpable mass. In cases of diffuse peritonitis, generalized tenderness, involuntary guarding and decreased or absent bowel sounds are noted. The presence of pneumaturia or fecaluria signifies the presence of a colovesical fistula. Severe abdominal distention suggests bowel obstruction. The diagnosis of acute diverticulitis is based on clinical findings and leukocytosis.