Ileus occurs when there is intestinal distention and either slowing or no passage of luminal contents without a demonstrable mechanical obstruction. The term “ileus” is derived from the Greek word eileós (εἰλέω) meaning “obstruction.”

Postoperative ileus is a type of functional bowel obstruction that occurs when there is a decrease in gut motility with dysfunction after surgery.

Etiology (of ileus, as a whole)

  • Metabolic: hypokalemia, hyponatremia, hypomagnesemia, uremia, diabetic coma, hypoparathyroidism
  • Neurogenic: postoperative ileus, spinal injury, retroperitoneal irritation
  • Pharmacologic: opiates (e.g., morphine, meperidine), anticholinergics, autonomic blockers, antihistamines, psychotropics (e.g., haloperidol, tricyclics)
  • Infections: pneumonia, peritonitis, sepsis


  • Multifactorial
  • Neurogenic, inflammatory, enteric hormones, electrolyte disturbances, and opioids all play a role in contributing to pathogenesis of postoperative ileus

Physical Exam

  • Abdominal distention
  • ± Flatus
  • ± Diarrhea
  • ± Nausea, vomiting 


  • CBC
  • CMP: hypokalemia, hypomagnesemia


  • Abdominal radiograph: dilated small and large bowel


  • Usually self-resolves
  • Conservative management
    • NPO
    • IVF
    • Treat electrolyte abnormalities
    • Discontinue medications that could have caused ileus
    • NG tube placement (support for selective over routine use; remove when output is minimal)

Relevant Information

  • Normal return times for intestinal motility after abdominal surgery
    • Small bowel: several hours
    • Stomach: 24 – 48 hours
    • Colon: 3 – 5 days
  • Most common form of functional bowel obstruction
  • Duration of the ileus usually correlates with the type of surgery and degree of surgical trauma
  • Enhanced Recovery After Surgery (ERAS) protocol: initiated in early 1990s with the goal of implementing measures before, during, and after surgery in order to reduce improve postoperative recovery time, reduce complications, and result in early return to daily activities


  • Prolonged hospital stay
  • Aspiration

Differential Diagnoses


  • Luckey, A., Livingston, E., and Taché, Y. Mechanisms and Treatment of Postoperative Ileus. Arch Surg. 2003; 138(2):206-214. doi: 10.1001/archsurg.138.2.206
  • Vather R, Bisset I. Management of Prolonged Post-Operative Ileus: Evidence-based Recommendations. ANZ J Surg. 2013; 83(5):319-324. doi: 10.1111/ans.12102