GASTROENTEROLOGY
DIVERTICULAR DISEASE
DIVERTICULOSIS
Definition & pathobiology (Lancet 2004;363:631)
• Acquired herniations of colonic mucosa and submucosa through the colonic wall
• Existing dogma is low-fiber diet → ↑ stool transit time and ↓ stool volume → ↑ intraluminal pressure → herniation where vasa recta penetrate, but now ?’d (Gastro 2012;142:266)
Epidemiology
• Prevalence higher w/ ↑ age (10% if <40 y; 50–66% if >80 y); “Westernized” societies
• Left side (90%, mostly sigmoid) > right side of colon (except in Asia, where R > L)
Clinical manifestations
• Usually asx, but 5–15% develop diverticular hemorrhage and <5% diverticulitis
• Nuts, etc. intake in asx diverticulosis does not ↑ risk of diverticulitis (JAMA 2008;300:907)
DIVERTICULITIS
Pathophysiology (NEJM 2007;357:2057)
• Retention of undigested food and bacteria in diverticulum → fecalith formation → obstruction → compromise of diverticulum’s blood supply, infection, perforation
• Uncomplicated: microperforation → localized infection
• Complicated (25%): macroperforation → abscess, peritonitis, fistula (65% w/ bladder), obstruction, stricture
Clinical manifestations
• LLQ abdominal pain, fever, nausea, vomiting, constipation
• PEx ranges from LLQ tenderness ± palpable mass to peritoneal signs & septic shock
• Ddx includes IBD, infectious colitis, PID, tubal pregnancy, cystitis, colorectal cancer
Diagnostic studies
• Plain abdominal radiographs to r/o free air, ileus or obstruction
• Abdominal CT (I+O+): >95% Se & Sp; assess complicated disease (abscess, fistula)
• Colonoscopy contraindicated acutely ↑ risk of perforation; do 6 wk after to r/o neoplasm
Treatment (Am J Gastro 2008;103:1550)
• Mild: outPt Rx indicated if Pt has few comorbidities and can tolerate POs
PO abx: (MNZ + FQ) or amox/clav for 7–10 d; liquid diet until clinical improvement, though recent evidence suggest abx may be unnecessary (Br J Surg 2012;99:532)
• Severe: inPt Rx if cannot take POs, narcotics needed for pain, or complications
NPO, IV fluids, NGT (if ileus)
IV abx (GNR & anaerobic coverage): amp/gent/MNZ or piperacillin-tazobactam
• Abscesses >4 cm should be drained percutaneously or surgically
• Surgery: if progression despite med Rx, undrainable abscess, free perforation or possibly recurrent disease (≥2 severe episodes)
• Colonic stricture: late complication of diverticulitis; Rx w/ endoscopic dilation vs. resection; colonoscopy after 6 wk to exclude neoplasm
Prevention
• Low-fiber diet immediately after acute episode; high-fiber diet when >6 wk w/o sx
• Consider mesalamine ± rifaximin if multiple episodes
• Risk of recurrence 10–30% w/in 10 y of 1st episode; more likely 2nd episode complicated
DIVERTICULAR HEMORRHAGE (ALSO SEE “GASTROINTESTINAL BLEEDING”)
Pathophysiology
• Intimal thickening and medial thinning of vasa recta as they course over dome of diver- ticulum → weakening of vascular wall → arterial rupture
• Diverticula more common in left colon; but bleeding diverticula more often in right colon
Clinical manifestations
• Painless hematochezia/BRBPR; can have abdominal cramping
• Usually stops spontaneously (~75%) but resolution may occur over hrs–days; ~20% recur
Diagnostic studies
• Colonoscopy: rapid prep w/ PEG-based solution via NGT (4–6 L over 2–4 h)
• Arteriography ± tagged RBC scan if severe bleeding
Treatment
• Colonoscopy: epinephrine injection ± electrocautery (NEJM 2000;342:78), hemoclip, banding
• Arteriography: intra-arterial vasopressin infusion or embolization
• Surgery: if above modalities fail & bleeding is persistent & hemodynamically significant