Small bowel diverticular disease

Small bowel diverticular disease encompasses small bowel diverticulosis and small bowel diverticulitis. In small bowel diverticulosis, one or more diverticula form through the small bowel wall, most commonly the duodenum. Small bowel diverticulosis is more common in adults ≥ 40 years of age and is either congenital or acquired, with causes of acquired small bowel diverticulosis thought to include increased intraluminal pressure or intestinal dyskinesia. Patients are usually asymptomatic but may present with chronic, nonspecific symptoms (e.g., abdominal pain, fever, diarrhea) and/or GI bleeding. Complications can be severe and include small bowel diverticulitis, severe hemorrhage, mechanical bowel obstruction, and pancreaticobiliary disorders. Diagnosis is typically based on imaging findings. Management depends on the clinical presentation. Asymptomatic patients require no treatment. Complications such as perforation, abscess, or severe hemorrhage often require surgery. Small bowel diverticulitis is the inflammation of one or more diverticula in the small bowel and is typically caused by diverticular obstruction. It is a complication of small bowel diverticulosis, most commonly jejunoileal diverticulosis, and usually affects older adults. Clinical features are often nonspecific (e.g., abdominal pain, fever, vomiting), and the differential diagnosis includes other causes of acute abdomen. Diagnosis is based on imaging findings (e.g., peridiverticular edema, diverticular wall thickening). Management depends on severity; patients with mild, uncomplicated cases are treated conservatively with bowel rest and broad-spectrum antibiotics. Surgery is the definitive treatment and is indicated for complications such as perforation, abscess, and obstruction.

This article only addresses acquired small bowel pseudodiverticula. For information on congenital true diverticula of the small bowel, see "Meckel diverticulum."

• CT abdomen, typically with IV and oral contrast, is the preferred imaging modality, particularly for suspected complications of small bowel diverticulosis (e.g., small bowel diverticulitis).
• MRI abdomen or magnetic resonance enterography can also be used for diagnosis of small bowel diverticulosis.
• GI bleeding due to small bowel diverticulosis may be diagnosed using:
  • Small bowel endoscopy (e.g., capsule or double-balloon enteroscopy): high yield
  • CT angiography or traditional angiography: for brisk bleeding
  • Nuclear medicine scan: slower bleeding
• Review of prior imaging studies may help confirm the presence of pre-existing small bowel diverticula in patients with small bowel diverticulitis.

Definition ^[1][2]

• A condition characterized by the presence of one or more pseudodiverticula or true diverticula in the small bowel wall
• Pseudodiverticula are most commonly located in the duodenum (60–79% of cases).

Epidemiology

• Incidence ^[1]
  • Detected in 0.2–4.5% of autopsies
  • Detected in 0.5–2.3% of small bowel contrast studies
• More common in adults ≥ 40 years of age ^[2]
• Typically detected in the 6th or 7th decade of life ^[2]
• No definitive sex predilection ^[1][2]

Etiology ^[1]

• Acquired pseudodiverticula
  • Intestinal dyskinesia or neuromuscular dysfunction leading to localized areas of increased pressure
  • Herniation occurs at points of weakness in the muscularis layer, typically where vasa recta penetrate the bowel wall on the mesenteric border.
• Intraluminal duodenal diverticulum (windsock diverticulum)
  • A congenital duodenal web forms a pulsion diverticulum as a result of peristalsis gradually pushing the web into the lumen
  • Involves three duodenal layers
  • Both surfaces are lined with epithelium.

Clinical features ^[1][2]

• Most patients are asymptomatic.
• Chronic, nonspecific symptoms, e.g.:
  • Dyspepsia
  • Abdominal pain
  • Change in bowel habits
  • Nausea and vomiting
  • Borborygmus
  • Diarrhea
• Gastrointestinal bleeding, e.g.:
  • Hematemesis
  • Melena
  • Hematochezia (jejunoileal diverticular bleeding)

Patients with jejunoileal diverticulosis are more likely to have persistent symptoms and acute complications than duodenal diverticulosis. ^[1]

Diagnosis ^[1][2]

Accurate diagnosis typically requires a strong level of clinical suspicion.

Imaging

• Preferred modality : CT abdomen with oral or IV contrast
• Alternative modalities
  • MRI abdomen
  • Magnetic resonance enterography
• Findings
  • Multiple round or ovoid, thin-walled outpouchings
  • Usually located on the mesenteric border
  • No plicae circulares
  • May contain air-fluid level

Laparotomy

• Gold standard
• Not the preferred modality as it is invasive

Diagnosis of bleeding from small bowel diverticula

• Small bowel endoscopy (e.g., capsule or double-balloon enteroscopy): high yield
• Angiography (e.g., CT angiography): for brisk bleeding
• Nuclear medicine scan: for slower bleeding
• See also "Approach to suspected small bowel bleeding."

Avoid oral contrast in patients with an acute GI bleed as it may interfere with therapeutic endoscopy or angiography. ^[1]

Differential diagnoses ^[2]

• Intra-abdominal abscess
• Pancreatic pseudocyst
• Cystic neoplasm
• Pseudosacculation (e.g., in Crohn disease)

Management ^[1][2]

• No treatment is required for asymptomatic individuals.
• Manage complications on a case-by-case basis, e.g.:
  • Treatment of GI bleeding
  • Treatment of small intestinal bacterial overgrowth
  • Management of bowel obstruction

Complications ^[1][2]

• Inflammatory
  • Small bowel diverticulitis (most common complication of jejunoileal diverticulosis) ^[1]
  • Peritonitis (due to gastrointestinal perforation)
  • Abscess formation
• Hemorrhage (most common complication of duodenal diverticulosis) ^[1]
• Mechanical bowel obstruction due to, e.g.:
  • Enterolith formation and impaction
  • Volvulus
  • Intussusception
  • Stricture or adhesions from prior inflammation
  • Compression (e.g., resulting from a distended diverticulum)
• Nonmechanical bowel obstruction (e.g., from intestinal dyskinesia)
• Small intestinal bacterial overgrowth leading to, e.g.:
  • Malabsorption
  • Nutritional deficiencies (e.g., vitamin B₁₂ deficiency and fat-soluble vitamin deficiencies )
• Anemia
• Pancreaticobiliary disorders (associated with periampullary diverticula)
  • Obstructive jaundice (i.e., due to Lemmel syndrome)
  • Cholelithiasis
  • Choledocholithiasis
  • Cholangitis
  • Pancreatitis
• Benign pneumoperitoneum

Definition ^[1][2]

• The inflammation of one or more small bowel diverticula (most commonly jejunoileal diverticula)
• Caused by stasis of contents within the diverticulum, resulting in venous outflow obstruction and infection

Epidemiology ^[3]

• Typically affects older adults
• Most common complication of jejunoileal diverticulosis

Etiology ^[1][2][3]

• Obstruction of the diverticulum due to, e.g.:
  • Fecalith
  • Enterolith
  • Mucosal edema of diverticular neck
• Predisposing factors include:
  • Foreign body
  • Cholelithiasis
  • Diverticular ulceration
  • Blunt trauma

Clinical features ^[1][2][3]

Presentation is often nonspecific and can mimic other causes of an acute abdomen.

• Abdominal pain (most common symptom)
• Fever
• Vomiting
• Diarrhea
• Peritonitis (typically with perforation)

Diagnosis ^[1][2][3]

• CT abdomen, typically with intravenous and oral contrast, is the imaging modality of choice.
• Findings:
  • Signs of peridiverticular inflammation (e.g., peridiverticular edema and fat stranding, diverticular wall thickening)
  • Inflammation is typically more pronounced along the mesenteric border (sparing of the antimesenteric side).
  • "Fecalized diverticulum" sign: fecalized content within the inflamed diverticulum

Differential diagnoses ^[1][2][3]

• Appendicitis
• Cholecystitis
• Pancreatitis
• Colonic diverticulitis
• Bowel ulceration or peptic ulcer disease
• Crohn disease
• Biliary colic or renal colic
• Pelvic inflammatory disease
• Ectopic pregnancy
• Malignancy

Management ^[1][2][3]

• Expectant management
  • Bowel rest
  • Broad-spectrum IV antibiotics (see "Empiric antibiotics for intraabdominal infections" for potential regimens)
  • Close observation
• Surgical management
  • Definitive treatment
  • Indications include:
    • Perforation
    • Abscess drainage
    • Bowel obstruction
    • Concern for bowel ischemia
    • Ongoing pain despite antibiotic therapy
    • Recurrent episodes of small bowel diverticulitis
  • Procedure: small bowel resection with primary anastomosis

Complications ^[1][2][3]

• Bowel perforation
• Abdominal abscess formation (e.g., intrahepatic abscess)
• Bowel obstruction (due to stricture or adhesion formation)
• Superior mesenteric vein thrombosis
• Portal venous gas
• Common bile duct obstruction (with duodenal diverticulitis)