Diverticular Disease

Definition and Classification

• Congenital (true) diverticula: All three coats of the bowel wall are present (e.g. Meckel's diverticulum)
• Acquired (false/pseudo) diverticula: No muscularis layer - only mucosa and serosa herniate through the muscular coat (e.g. sigmoid diverticular disease)

Epidemiology

• Found in the left colon (predominantly sigmoid) in ~75% of those over 70 years in the Western world
• 10-30% of those with diverticulosis will develop symptomatic complications
• Right-sided diverticular disease is more common in South-East Asia
• Rare in Africa and Asia, where dietary fibre intake is high (Burkitt's observation)

Aetiology and Pathogenesis

1. Low-fibre Western diet - decreased stool bulk increases intraluminal pressure
2. Altered collagen structure with ageing - weakens bowel wall
3. Disordered colonic motility - segmentation contractions generate high pressure
4. Narrow sigmoid lumen - highest pressure generated here

Complications

Hinchey Classification of Complicated Diverticulitis

Clinical Features

• Distension, flatulence, lower abdominal heaviness - often indistinguishable from IBS
• Symptoms thought to arise from increased luminal pressure and visceral hypersensitivity

• Persistent left iliac fossa pain (can be right-sided if sigmoid loops across midline - "left-sided appendicitis")
• Accompanying diarrhoea or constipation
• Tenderness over the left iliac fossa
• Tender, thickened sigmoid on palpation
• Tender rectal mass if abscess has formed
• Systemic upset (fever, raised WBC, raised CRP)

• Systemic sepsis
• Generalised tenderness and guarding

• Typically painless and profuse
• Bright red blood per rectum (sigmoid) or darker blood (right-sided)
• Torrential bleeding is rare; angiodysplasia is more common cause of massive LGI haemorrhage

• Colovesical (most common): recurrent UTIs, pneumaturia (pathognomonic), faecaluria
• Colovaginal: more common post-hysterectomy
• Colocutaneous: rare without prior intervention

Investigations

• CT abdomen/pelvis (spiral/contrast): Investigation of choice. Excellent sensitivity/specificity for bowel wall thickening, abscess, extraluminal gas, free perforation. Has transformed management of complicated diverticular disease
• Plain AXR/CXR: Can demonstrate pneumoperitoneum in free perforation
• Contrast enema or CT colonography: Used after 6 weeks (not acutely - risk of perforation) to exclude coexisting carcinoma and assess extent of disease; can demonstrate fistulae

• Deferred 6 weeks after acute episode
• Used to exclude concurrent colorectal carcinoma
• Can be technically difficult / dangerous due to narrowed lumen; significant perforation risk
• May be supplemented by CT virtual colonoscopy

Management

Conservative / Medical

• High-fibre diet (at least 25 g/day, insoluble fibre preferred - wheat bran, bran muffins) and bulk-forming laxatives - evidence for benefit in diverticulosis is limited but widely recommended
• Antispasmodics (e.g. mebeverine) for recurrent pain
• Patients should NOT be told to avoid nuts or seeds - no evidence these precipitate diverticulitis, per Sleisenger and Fordtran's GI and Liver Disease

Acute Diverticulitis - Uncomplicated

• Outpatient management if mild, immunocompetent, no systemic sepsis
• Antibiotics: Selective use only - emerging evidence that uncomplicated diverticulitis is self-limiting and may not require antibiotics in immunocompetent patients without systemic infection signs (confirmed by CT)
• Bowel rest, analgesia, hydration

Acute Diverticulitis - Complicated

• Hospital admission, IV antibiotics (broad-spectrum, cover gram-negatives and anaerobes)
• Hinchey I/II (abscess): CT-guided percutaneous drainage in stable patients avoids emergency surgery
• Hinchey III/IV (peritonitis): Emergency surgery required

Surgical Management

• Generalised peritonitis
• Failure to respond to optimum medical management

1. Hartmann's procedure (traditional emergency approach):
   • Sigmoid resection + end colostomy (left iliac fossa) + closure of rectal stump
   • Colostomy reversal as a second stage
   • High morbidity; ~40% of colostomies never reversed
2. Primary resection with anastomosis + defunctioning loop ileostomy
   • Increasingly favoured in selected patients (less contamination, good performance status)
3. Laparoscopic lavage and drainage
   • For Hinchey III (purulent peritonitis) in selected patients
   • Avoids stoma; growing evidence base but remains controversial

Diet, Lifestyle, and Prevention

• High-fibre diet reduces intraluminal pressure and risk of diverticulum formation
• Obesity and physical inactivity increase risk of symptomatic diverticular disease in both men and women
• Probiotics (especially Lactobacillus strains): one systematic review of 11 studies showed symptom regression in the majority of 764 patients, but high-quality data are lacking; current AGA guidelines recommend against routine probiotic use after uncomplicated diverticulitis

Key Points Summary

• Bailey and Love's Short Practice of Surgery, 28th Ed., Ch. 77 (pp. 1389-1390)
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease
• Rosen's Emergency Medicine: Concepts and Clinical Practice

Diverticular Disease - Textbook Images

Fig. 77.13 - CT Scan: Diverticular Abscess

Fig. 77.14 - Colonoscopy: Right-Sided Diverticula

Fig. 77.15 - Hartmann's Procedure Diagram

• End colostomy brought out through the left iliac fossa (red stoma with sutures, visible on the patient's left)
• Oversewn rectal stump (shown as a small capped remnant at the pelvis, marked with dashed line) - the rectum is closed and left in situ
• The remaining colon (ascending, transverse, descending) remains intact

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