PassFinals
Colorectal Surgery

Diverticular Disease

Diverticulosis means asymptomatic colonic diverticula, diverticular disease means symptoms without systemic inflammation, and acute diverticulitis is sudden inflammation or infection that may be uncomplicated or complicated by abscess, perforation, fistula, stricture, obstruction or sepsis; diverticular bleeding is often a separate painless presentation.

In a nutshell

Use the terms precisely: diverticulosis is asymptomatic, diverticular disease causes symptoms without systemic inflammation, and acute diverticulitis is sudden local inflammation or infection. Systemically well uncomplicated disease often needs supportive care without antibiotics (see BNF), while uncontrolled pain plus a NICE complication feature requires same-day hospital assessment. For complicated disease, follow the NICE NG147 abscess and operative pathway with urgent colorectal input.

Classic presentation

An older adult develops constant, usually severe left lower-quadrant pain with fever and focal tenderness; guarding, a mass, sepsis, fistula symptoms or obstruction converts the stem to suspected complicated acute diverticulitis.

Key points

  • Diverticulosis is asymptomatic; diverticular disease produces intermittent pain or bowel symptoms without systemic illness; acute diverticulitis produces sudden constant pain with local inflammation or infection.
  • The mechanism is multifactorial. Do not reduce it to a deterministic low-fibre, high-pressure or faecolith-obstruction story.
  • Modified Hinchey: Ia phlegmon, Ib confined pericolic abscess, IIa drainable pelvic or distant abscess, IIb complex abscess with fistula, III purulent peritonitis and IV faecal peritonitis.
  • NICE requires same-day assessment for uncontrolled abdominal pain plus a sign of abscess, peritonitis, sepsis, fistula or intestinal obstruction.
  • In suspected complicated disease with raised inflammatory markers, NICE recommends contrast CT within 24 hours of admission; do not use acute colonoscopy or sigmoidoscopy.
  • A systemically well person with uncomplicated acute diverticulitis can be managed with a no-antibiotic strategy and safety-netting; reserve antibiotics for systemic illness, immunosuppression, significant comorbidity or complicated disease (see BNF).
  • Diverticular bleeding is often painless. A shock index greater than 1 means unstable bleeding and CT angiography after resuscitation; if CT angiography is negative, assess urgently for a brisk upper-GI source and consider upper-GI endoscopy. Stable self-terminating bleeding is risk-stratified with Oakland, with 8 or less potentially suitable for discharge and urgent investigation and greater than 8 requiring admission.
  • NICE recommends considering feasible percutaneous drainage or surgery for an abscess greater than 3 cm, with urgent colorectal and interventional-radiology input.
  • For generalised peritonitis, NICE offers laparoscopic lavage or resection after risk-benefit discussion, with resection for faecal peritonitis; obtain urgent consultant colorectal and anaesthetic input.
  • After resolved uncomplicated CT-confirmed disease, follow-up colon imaging is selective; ACPGBI recommends optical or virtual colonoscopy after 6 weeks following complicated disease unless equivalent imaging occurred within the preceding 2 years.

First-line investigation

First decide whether the patient has a same-day complication feature. In hospital suspected complicated disease, obtain FBC, urea and electrolytes and CRP, then contrast CT within 24 hours when inflammatory markers are raised.

Management

Recognise complicated disease and bleeding

  • Refer for same-day hospital assessment when uncontrolled abdominal pain is accompanied by an abdominal mass or perirectal fullness, guarding or rigidity, sepsis features, faecaluria or pneumaturia or pyuria or faeces passed vaginally, or colicky pain with absolute constipation, vomiting or distension.1,4
  • Resuscitate perforation, peritonitis, obstruction or sepsis using ABCDE, urgent senior colorectal and anaesthetic review and prompt source control; use the local sepsis and intra-abdominal infection pathway (see BNF).1,4,2
  • For lower-GI bleeding, shock index greater than 1 means unstable and requires CT angiography after initial resuscitation, followed promptly by catheter angiography and embolisation when active extravasation is found. If CT angiography is negative, assess urgently for a brisk upper-GI source and consider upper-GI endoscopy. In stable self-terminating bleeding, Oakland 8 or less may support discharge with urgent investigation if no other admission reason exists; greater than 8 means major bleeding, admission and colonoscopy on the next available list. Scores do not override clinical judgement.3

Confirm anatomy and severity

  • In suspected complicated acute diverticulitis, obtain FBC, urea and electrolytes and CRP. Raised inflammatory markers trigger contrast CT within 24 hours under NICE; if contrast is contraindicated use non-contrast CT, MRI or expert ultrasound.1
  • ACPGBI recommends contrast-enhanced CT across suspected acute diverticulitis in the emergency surgical setting to confirm the diagnosis, stage complications and find alternatives. This broader emergency recommendation does not mean every systemically well community presentation needs immediate imaging.2,1
  • Do not diagnose acute diverticulitis with colonoscopy or sigmoidoscopy because of perforation risk. Defer cancer exclusion until recovery and select it according to disease complexity, CT findings and NG12 concern.6,2,5

Use selective non-operative treatment

  • If acute diverticulitis is uncomplicated and the person is systemically well, consider no antibiotics, give simple analgesia, allow oral intake as tolerated and provide clear reassessment and return advice (see BNF).1,2
  • Offer an oral antibiotic strategy for systemic illness without a same-day complication criterion, immunosuppression or significant comorbidity. NICE's listed oral courses are 5 days before review. Oral ciprofloxacin is only a specialist-advised intravenous-to-oral switch when other recommended agents are inappropriate, under current MHRA restrictions (see BNF).1,7,8
  • Admitted suspected complicated disease requires intravenous antibiotics, scan-guided review within 48 hours or sooner and step-down to oral treatment where possible; review ongoing need if CT shows uncomplicated disease. Follow MHRA restrictions if a fluoroquinolone is considered (see BNF).1,4,7,8

Drain or operate using the normative NICE pathway

  • Consider feasible percutaneous drainage or surgery for a diverticular abscess greater than 3 cm, and use oral antibiotics where possible for a smaller abscess. Involve colorectal surgery and interventional radiology, culture drained pus and re-image non-response or deterioration; NICE allows up to 14 days of antibiotics after clinical review, not automatically (see BNF).1,4,7
  • For perforation with generalised peritonitis, NICE offers laparoscopic lavage or resection after risk-benefit discussion and requires resection for faecal peritonitis. Obtain urgent consultant colorectal and anaesthetic input and individualise source control to physiology, contamination and operative risk.1,4
  • If resection is required, primary anastomosis with or without diversion and Hartmann's procedure are options. Choose from physiology, contamination, comorbidity, performance status, immunosuppression, expertise and likely stoma reversal, not a rule that Hartmann's is always first-line.1,2

Prevent harm, reassess and exclude malignancy selectively

  • For diverticular disease, use diet, fluids, gradual fibre increase, exercise, weight management and smoking cessation; avoid NSAIDs and opioids where possible, and do not use antibiotics for chronic symptoms or prophylaxis against recurrence (see BNF).1,2
  • Do not arrange routine 6 to 8 week colonoscopy after every uncomplicated episode. After complicated disease, ACPGBI recommends optical or virtual colonoscopy after 6 weeks unless the colon was imaged within the preceding 2 years; investigate sooner through NG12 when cancer concern exists.2,5,6
  • Consider elective open or laparoscopic resection after complicated diverticulitis when symptoms continue, particularly with fistula or stricture. Recurrence count alone is not a universal operation threshold; use symptoms, complications, quality of life, frailty, risk and patient preference.1,2

Exam traps

  • Do not call incidental asymptomatic diverticula diverticular disease: NICE calls this diverticulosis.
  • Do not prescribe antibiotics automatically for systemically well uncomplicated acute diverticulitis; use selective treatment and safety-netting (see BNF).
  • The same-day NICE trigger is uncontrolled abdominal pain plus a listed complication feature, not pain alone.
  • A normal inflammatory marker result should prompt reconsideration of alternative diagnoses rather than proving or excluding diverticulitis by itself.
  • Do not perform colonoscopy or sigmoidoscopy during acute diverticulitis, and do not promise routine 6 to 8 week colonoscopy after every uncomplicated attack.
  • Diverticular haemorrhage is often painless and does not prove active diverticulitis.
  • For an abscess greater than 3 cm, NICE says to consider feasible percutaneous drainage or surgery; involve colorectal surgery and interventional radiology.
  • NICE offers laparoscopic lavage or resection for generalised peritonitis after discussion, with resection for faecal peritonitis; do not turn this into routine management of uncomplicated disease.
  • Do not treat Hartmann's procedure as the default operation for all perforated diverticulitis; primary anastomosis with or without diversion is also an option in selected patients.

Illustrations

Formation of colonic diverticulaCross-sectional diagram of mucosa and submucosa protruding through the muscular wall near a penetrating vasa recta, with a note that pressure, wall structure, ageing, genetics, motility, diet and microbiome interact rather than a single low-fibre mechanism explaining all disease.PassFinals · original
Acute sigmoid diverticulitis on CTAxial contrast CT showing a thick-walled sigmoid segment, an adjacent diverticulum and pericolic fat stranding, with review for abscess, extraluminal gas, fistula and obstruction.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0
Spectrum of diverticular complicationsIllustration contrasting contained phlegmon or abscess, free perforation with peritonitis, colovesical or colovaginal fistula, fibrotic stricture with obstruction, and a separate arterial diverticular-bleeding pathway.PassFinals · original

Key sources

  1. NICE, Diverticular disease: diagnosis and management, recommendations (NG147)Published 27 Nov 2019
  2. ACPGBI, Consensus guidelines in emergency colorectal surgeryPublished 27 Feb 2021
  3. British Society of Gastroenterology, Diagnosis and management of acute lower gastrointestinal bleedingPublished 12 Feb 2019
  4. NICE, Suspected sepsis in people aged 16 or over: recognition, assessment and early management (NG253)Published 19 Nov 2025
  5. NICE, Suspected cancer: recognition and referral (NG12)Published 23 Jun 2015 | Updated 15 Apr 2026
  6. NICE, Diverticular disease: diagnosis and management, rationale and impact (NG147)Published 27 Nov 2019
  7. BNF, Antibacterials: principles of therapy
  8. MHRA, Fluoroquinolone antibiotics: must now only be prescribed when other commonly recommended antibiotics are inappropriatePublished 22 Jan 2024

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.