Description

• Blockage of material from transiting the intestine
• This blockage can be partial or complete. It can be the result of mechanical or functional causes.
• Consider intestinal obstruction in the differential diagnosis of patients presenting with abdominal pain, distention, emesis, and obstipation.
• System(s) affected: gastrointestinal (GI)

Geriatric Considerations
If patient is an elderly, consider

• Colonic neoplasm
• Chronic constipation/fecal impaction
• Pseudoobstruction (Ogilvie syndrome)
• Volvulus

Pediatric Considerations
In young children and infants, consider:

• Pyloric stenosis: infant 3 to 6 weeks of age with postprandial, nonbilious, projectile vomiting
• Intestinal malrotation/volvulus: sudden-onset, bilious vomiting with acute abdomen symptoms
• Hirschsprung disease: failure to pass stool in first days of life, explosive expulsion of gas, and stool after digital rectal exam
• Intussusception: distention, intermittent abdominal pain, currant jelly stools

• Internal hernia: sudden onset of abdominal pain, vomiting, abdominal distention, and “whirl” sign on CT

Epidemiology

Predominant sex: male = female

Prevalence
In the United States: Intestinal obstruction accounts for ~20% of all admissions for acute abdominal conditions.

Etiology and Pathophysiology

• Mechanical bowel obstruction causes distention and accumulation of fluid and gas in bowel lumen.
• Increased intraluminal pressure and peristaltic contractions increases capillary and venous pressure of bowel wall while decreasing absorption and lymphatic drainage. This may lead to bowel ischemia and necrosis if obstruction is prolonged.
• Luminal lesions:
  • Stool impaction
  • Gallstones
  • Meconium (newborns)
  • Intussusception
• Intrinsic lesions:
  • Congenital (e.g., atresia and stenosis, imperforate anus, duplications, Meckel diverticulum)
  • Trauma: foreign body
  • Inflammatory (e.g., Crohn disease, diverticulitis, ulcerative colitis, radiation, toxic ingestions)
  • Neoplastic (most common cause of large bowel obstruction in adults)
  • Miscellaneous (e.g., endometriosis, pseudomyxoma peritonei)
• Extrinsic lesions
  • Adhesions (most common cause of small bowel obstruction [SBO] in adults; history of prior abdominal surgery). Laparoscopic surgery significantly reduces the rates of adhesive SBO compared with open surgery (1)[A].
  • Hernia
  • Masses (e.g., annular pancreas, anomalous vasculature, abscess and hematoma, neoplasm)
  • Volvulus
  • Neuromuscular defect (e.g., megacolon, neuro-/myopathic motility disorders)

Genetics
Potentially related to underlying etiology

Risk Factors

• Previous abdominal and/or pelvic surgery (particularly with open surgical techniques)
• Hernia
• Chronic constipation
• Cholelithiasis
• Inflammatory bowel disease
• Ingested foreign bodies: pica
• Diverticular disease

General Prevention

Treat underlying conditions (e.g., tumors and hernias).