Pocket Medicine

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