Diverticulitis
Diverticulitis is inflammation, and often micro or macroperforation, of a colonic diverticulum, most commonly in the sigmoid colon, arising from fecalith obstruction or erosion causing localized inflammation.
Classified as uncomplicated (localized inflammation) or complicated (abscess, fistula, obstruction, or free perforation with peritonitis).
Left iliac fossa pain (given the predominance of sigmoid involvement), fever, and localized tenderness, sometimes with a palpable mass, alongside altered bowel habit, nausea, and, occasionally, urinary symptoms if the inflamed segment is adjacent to the bladder.
Complicated disease presents with more marked systemic toxicity, a larger palpable mass (abscess), signs of bowel obstruction, pneumaturia or fecaluria (colovesical fistula), or generalized peritonitis (free perforation).
CT abdomen/pelvis with contrast is the investigation of choice, confirming diagnosis, grading severity (commonly using the Hinchey classification for perforated disease: I localized pericolic abscess, II pelvic abscess, III purulent peritonitis, IV feculent peritonitis), and identifying complications.
Colonoscopy is avoided in the acute phase given perforation risk, but performed 6 to 8 weeks after resolution to exclude an underlying malignancy, particularly important given the overlapping presentation with colorectal cancer.
- Uncomplicated diverticulitis, mild, tolerating oral intake: increasingly managed without antibiotics in immunocompetent patients per current evidence (a shift from historical routine antibiotic use), with close outpatient follow-up; antibiotics are still used where the patient is frail, immunocompromised, has significant comorbidity, or symptoms are more than mild: co-amoxiclav 625 mg PO tds for 5 days, or ciprofloxacin plus metronidazole if penicillin-allergic
- Uncomplicated diverticulitis requiring admission (significant pain, unable to tolerate oral intake, or comorbidity): IV fluids, analgesia, and IV antibiotics (co-amoxiclav, or ceftriaxone plus metronidazole) if used, per the same threshold considerations as above
- Complicated diverticulitis: abscess above 3 to 4 cm is managed with percutaneous drainage plus IV antibiotics; smaller abscesses may respond to antibiotics alone
- Hinchey III/IV (purulent/feculent peritonitis): emergency surgery, historically Hartmann's procedure (sigmoid resection with end colostomy), though primary resection with anastomosis (with or without diverting loop ileostomy) is increasingly used in selected, hemodynamically stable patients at specialist centers
- Recurrent diverticulitis: elective sigmoid colectomy is considered on an individualized basis after 2 or more episodes, or after a single complicated episode, weighing recurrence risk against surgical risk, rather than as an automatic threshold
- High-fiber diet and adequate hydration for prevention once the acute episode has resolved
Referral: general/colorectal surgery for complicated disease, abscess requiring drainage, or recurrent disease being considered for elective resection.
