Large bowel obstruction

Background

• Much less common than SBO, but more ominous (frequently associated with malignancy)
  • LBO more common in elderly, and generally has more insidious onset than SBO
• Most commonly occurs in the left (descending) colon
  • Obstruction originating from the left colon is likely to manifest with symptoms earlier than obstruction originating from the right colon, because the lumen from the descending colon and the sigmoid is smaller.

Causes

• Adhesions
• Diverticular disease
• Fecal impaction
• Hernias
• Neoplasm
• Strictures
• Pseudo-obstruction (Ogilvie's Syndrome)
• Volvulus

Clinical Features

• Abdominal pain
• Abdominal distension
  • Distension is greater if the ileocecal valve is competent (it creates a closed loop obstruction). If the ileocecal valve is not competent, you are more likely to see some dilation of the small bowel as well
• Obstipation
• Vomiting
• Palpable abdominal mass (could be distended bowel or could be tumor causing obstruction)
• Fever and tachycardia should prompt investigation for gangrene and perforation

Differential Diagnosis

Diffuse Abdominal pain

• Abdominal aortic aneurysm
  • Aortocaval fistula
• Acute gastroenteritis
• Aortoenteric fisulta
• Appendicitis (early)
• Bowel obstruction
  • Large bowel obstruction
    • Ogilvie's syndrome
  • Small bowel obstruction
  • Malignant bowel obstruction
• Bowel perforation
• Diabetic ketoacidosis
• Gastroparesis
• Hernia
• Hypercalcemia
• Inflammatory bowel disease
• Mesenteric ischemia
  • Mesenteric vein thrombosis
• Pancreatitis
• Peritonitis
• Sickle cell crisis
• Spontaneous bacterial peritonitis
• Volvulus

Diagnosis

• Labs
  • None are diagnostic
  • Check electrolytes to assess for dehydration
  • Leukocytosis could indicate gangrene or perforation
  • Anemia could indicate malignancy as source of obstruction
  • ABG may help assess if the patient has respiratory compromise from diaphragmatic compression
• Imaging
  • XR
    • Sensitivity of 69% to 80% for detecting bowel obstruction, but insensitive for diagnosing cause or location
    • Upright films can detect pneumoperitoneum, hollow viscus perforation
    • Distended colon (small bowel may appear distended as well if the ileocecal valve is competent)
    • Cecal diameter of ≥12cm is associated with higher risk of perforation
  • CT
    • Can usually identify the cause of obstruction, except in cases of pseudo-obstruction
    • Sensitivity for diagnosing large bowel obstruction as high as 90% (not as high as for small bowel obstruction)
    • Can also diagnose intestinal ischemia
  • Colonoscopy
    • Can be used to rule-out pseudo-obstruction in patients who are not candidates for urgent surgical intervention

Management

• Rehydration
• NPO status
• Pain management
• Gastric decompression with NGT if pt has significant vomiting or evidence of small bowel distension
• Antibiotics if gangrene or perforation is suspected (need gram-negative and anaerobic coverage)

Treatment of specific etiologies of LBO

• Diverticular Abscess: percutaneous drainage
• Volvulus: endoscopic decompression
• Pseudo-obstruction: endoscopic decompression
• Intussusception: surgical intervention

Disposition

• Admission for rehydration/resuscitation
• Appropriate consultation (GI, surgery, IR)

See Also

• Small Bowel Obstruction (SBO)
• Ogilvie's Syndrome