Diverticulitis is acute inflammation of colonic diverticula. In Western societies, left colon (sigmoid) is most commonly affected (85-90%). Diverticular disease has 50-70% prevalence in those over 60, but only 10-25% become symptomatic. Complications include abscess, perforation, fistula, and stricture. CT has 94% sensitivity and 99% specificity for diagnosis and is the gold standard. Hinchey classification determines complication grade and treatment strategy.
Age Range
40-85
Peak Age
60
Gender
Equal
Prevalence
Common
Diverticula are herniations of mucosa and submucosa through the colonic wall at vasa recta penetration points (muscularis propria weak points) — they are false (pseudo) diverticula, not true (all layers). Obstruction of the diverticular lumen by fecalith or inspissated food debris initiates inflammation — microperforation, pericolic inflammation, and abscess may develop. Obstruction increases intraluminal pressure, mucosal erosion and bacterial translocation occur. On CT, the inflamed diverticulum is surrounded by pericolic fat stranding — indicating spread of inflammation to surrounding tissues. Diverticular wall thickens and enhancement increases. In complicated diverticulitis, perforation appears as free air, abscess as rim-enhancing collection, and fistula tracts.
The combination of an inflamed diverticulum with thickened wall and surrounding pericolic fat stranding is the signature finding of acute diverticulitis. Presence of diverticula and localization of inflammatory changes to a focal diverticulum distinguishes from adenocarcinoma.
Inflamed diverticulum: thickened-wall diverticulum with surrounding pericolic fat stranding. Inflammation focus may localize to a single diverticulum.
Report Sentence
An inflamed diverticulum with significant pericolic fat stranding is seen in the sigmoid colon, consistent with acute diverticulitis.
Segmental symmetric/concentric wall thickening in sigmoid colon. Thickening usually 4-15 mm. Length may be 5-15 cm.
Report Sentence
Segmental concentric wall thickening measuring approximately ___ cm in length is seen in the sigmoid colon.
Pericolic abscess: rim-enhancing fluid collection. Hinchey I: pericolic micro-abscess (<4 cm), Hinchey II: pelvic abscess (>4 cm). Abscess content may contain air bubbles.
Report Sentence
A rim-enhancing pericolic abscess measuring ___ cm is seen adjacent to the sigmoid colon, consistent with Hinchey stage ___.
Pericolic/peritoneal free air — indicator of perforation. Localized air suggests pericolic perforation (Hinchey I-II), diffuse free air suggests generalized peritonitis (Hinchey III-IV).
Report Sentence
Free air is seen around the sigmoid colon/peritoneal cavity, suggesting diverticular perforation.
Sigmoid colon wall thickening with hyperechoic pericolic fat (inflammation) on US. Inflamed diverticulum may appear as echogenic focus. US can be an alternative to CT for emergency evaluation.
Report Sentence
Sigmoid colon wall thickening with surrounding hyperechoic fat tissue is seen in the left lower quadrant, consistent with diverticulitis.
Colovesical fistula: abnormal connection between colon and bladder. Air in bladder (pneumaturia) and/or oral contrast seen in bladder is diagnostic.
Report Sentence
A colovesical fistula between the sigmoid colon and bladder is seen with air present at the bladder dome.
Criteria
Fat stranding and wall thickening present. No abscess, perforation, fistula, or obstruction.
Distinct Features
75-85% of cases. Antibiotic therapy ± diet modification. Colonoscopy recommended 6-8 weeks later (malignancy exclusion).
Criteria
Hinchey I: pericolic/mesocolic abscess (<4 cm). Hinchey II: pelvic abscess (>4 cm).
Distinct Features
Hinchey I: IV antibiotics. Hinchey II: percutaneous drainage + antibiotics. Interval colectomy debated.
Criteria
Hinchey III: generalized purulent peritonitis. Hinchey IV: generalized fecal peritonitis.
Distinct Features
Emergency surgery: Hartmann procedure or primary anastomosis ± diverting ileostomy. Mortality may reach 40% in Hinchey IV.
Distinguishing Feature
Adenocarcinoma shows asymmetric wall thickening, shouldered margins, and lymphadenopathy. Diverticulitis shows symmetric/concentric thickening, diverticula, and pericolic fat stranding. Distinction may be difficult — colonoscopy at 6-8 weeks recommended.
Distinguishing Feature
Appendicitis shows dilated appendix with localized inflammation in the right lower quadrant. Cecal diverticulitis may show similar fat stranding but inflamed diverticulum is seen in the cecal wall.
Distinguishing Feature
Ischemic colitis shows more diffuse segment involvement, submucosal edema/hemorrhage, and vascular watershed area (splenic flexure) involvement. Diverticulitis shows focal inflamed diverticulum and diverticula.
Distinguishing Feature
Crohn shows skip lesions, comb sign, fistula tracts, and asymmetric mesenteric-sided involvement. Diverticulitis shows symmetric thickening in sigmoid colon with inflamed diverticulum.
Urgency
urgentManagement
medicalBiopsy
Not NeededFollow-up
6-monthTreatment determined by Hinchey stage. Uncomplicated: oral/IV antibiotics, diet. Hinchey I: IV antibiotics. Hinchey II: percutaneous drainage + antibiotics. Hinchey III-IV: emergency surgery (Hartmann procedure or primary anastomosis). Colonoscopy at 6-8 weeks is mandatory for malignancy exclusion in all cases — diverticulitis masks concurrent cancer in 1-2% of cases. Elective sigmoid colectomy planned for recurrent or complicated diverticulitis. Follow-up: CT for symptom recurrence, 6-month clinical evaluation.
Uncomplicated diverticulitis is treated with antibiotics. Abscess is drained. Perforation requires emergency surgery. Elective colon resection is considered for recurrent episodes.