Fact-sheet: Diverticulitis of colon
Updated on 06/26/2026 at 12:02 PM
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Definition
Diverticulitis of colon is an intramural and pericolic infectious and inflammatory process resulting from perforation (micro or macro) of a colonic diverticulum.
Colonic diverticula are pseudodiverticula (herniation of the mucosa and submucosa through the muscularis propria) typically measuring 5 to 10 mm in diameter.
Locations:
- Rectosigmoid (70-90%),
- Left colon (25%),
- Transverse colon (4%)
- Right colon/cecum (1%).
Clinical features
Classic form (left-sided): Left iliac fossa pain, tenderness, fever, palpable mass, and change in bowel habits.
Right-sided diverticulitis: Mimics appendicitis (right iliac fossa pain). It more commonly affects younger patients (< 50 years) and is frequent in patients of Asian descent (30%).
Simple diverticulosis: Often asymptomatic; can cause rectal bleeding in 30% of cases.
Laboratory findings
- Leukocytosis.
- Elevated C-reactive protein (CRP), useful for predicting clinical severity.
- Possible anemia or presence of blood in the stool.
Radiography
Plain abdominal radiograph (obsolete): Useful to look for pneumoperitoneum in case of free perforation.
Barium enema (obsolete): Generally contraindicated in the acute phase. It may show filling defects (diverticula) and luminal narrowing with a "sawtooth" or "picket-fence" appearance (related to spasm or muscular hypertrophy).
Ultrasound
Ultrasound may demonstrate:
- Pericolic inflammation: Hyperechogenicity of the fat with ill-defined hypoechoic areas.
- Pericolic abscess: Hypoechoic collection sometimes containing internal echoes.
- Doppler: Hyperemia of the inflamed pericolic fat.
CT
Reference examination. Volumetric acquisition after IV injection of iodinated contrast material.
Cardinal signs:
- Wall thickening: Typically segmental and long (> 10 cm).
- Pericolic fat infiltration: "Stranding" appearance.
- Presence of diverticula: Essential for the positive diagnosis.
Signs of complicated diverticulitis:
- Abscess: Extraluminal fluid collection with peripheral enhancement.
- Pneumoperitoneum: Pericolic gas bubbles (microperforation) or free intraperitoneal gas (free perforation).
- Vascular congestion: Engorgement of the mesocolic vessels (comb sign).
- Fistulas: Communication with the bladder (intravesical gas), vagina, or skin.
- Pylephlebitis: Septic thrombophlebitis of the mesenteric or portal vein, potentially leading to hepatic abscesses.
Vascular intervention
Percutaneous drainage is a major alternative to surgery for abscesses.
- Indications: Any febrile collection > 4-5 cm, or persistence of symptoms despite antibiotic therapy.
- Advantages: Allows avoidance of emergency surgery or a single-stage delayed procedure.
- Precautions: Adequate hemostasis (PT > 70%, platelets > 70,000/µL).
Management
- Diagnosis: Confirmation by abdominal CT.
- Medical treatment: Antibiotics, bowel rest, and IV fluid resuscitation.
- Intervention: Percutaneous drainage of large abscesses. Upfront surgery if generalized peritonitis.
- Follow-up: Delayed colonoscopy (after resolution of symptoms) is recommended if there is any doubt regarding malignancy, particularly in cases of complicated diverticulitis or atypical CT findings.
Classification
The most recent classification used is the modified Hinchey classification (Barat et al. 2016):
Differential diagnosis
- Colon carcinoma: Suggestive findings: short segment (< 10 cm), markedly thickened walls (> 2 cm), pericolic lymph nodes (Sp 85%), abrupt luminal mass, and absence of marked pericolic inflammation.
- Epiploic appendagitis: Primary inflammation of an epiploic appendage. Pericolic fatty mass with an inflammatory rim ("hyperdense ring sign"), without significant thickening of the adjacent colon.
- Ischemic colitis: Often involves watershed areas (splenic flexure), thumbprinting sign.
- Crohn disease: Often more extensive involvement, affecting the terminal ileum.
- Pseudomembranous colitis: Massive, diffuse wall thickening, accordion sign.
