What is an ileus?

What is an Ileus?

An ileus is a functional obstruction of the bowel characterized by the failure to propel luminal contents in the absence of a mechanical obstructing lesion, resulting in symptoms similar to intestinal obstruction such as colicky abdominal pain, nausea, vomiting, abdominal distension, and often a dilated bowel. 1, 2

Types and Pathophysiology

• Ileus refers to a temporary impairment in bowel function characterized by obstipation, vomiting, bowel distension, and intolerance of oral intake 1
• Unlike mechanical bowel obstruction, ileus is caused by a failure of coordinated intestinal propulsion rather than a physical blockage 1, 3
• The term "intestinal dysmotility" encompasses conditions where there is failure to propel luminal contents without an organic obstructing lesion 1
• Ileus can be classified as:
  • Adynamic or paralytic ileus: caused by impaired intestinal muscle contractions 4
  • Functional ileus: caused by uncoordinated intestinal contractions 4

Causes

• Common causes of acute or reversible ileus include:
  • Abdominal surgery (postoperative ileus) 1, 2
  • Trauma 1
  • Sepsis 1, 5
  • Metabolic disturbances (e.g., hypokalemia) 1, 6
  • Endocrine problems (e.g., hypothyroidism) 1
  • Medications (especially opioids and anticholinergics) 6, 5
• Ileus can also occur in critically ill patients due to multiorgan failure and mechanical ventilation 5

Clinical Presentation

• Symptoms mimic those of mechanical bowel obstruction and include:
  • Colicky abdominal pain 1
  • Nausea and vomiting 1
  • Abdominal distension 1
  • Absence of flatus and bowel movements 2
• Physical examination may reveal:
  • Distended abdomen 1
  • Tympanic percussion 7
  • Diminished or absent bowel sounds 2

Complications

• Ileus can lead to several serious complications:
  • Intestinal bacterial overgrowth 3
  • Bacterial translocation and systemic infections 3
  • Increased intra-abdominal pressure 3
  • Abdominal fluid sequestration with systemic hypovolemia 3
  • Abdominal compartment syndrome in severe cases 3

Diagnosis

• Diagnosis is based on clinical presentation, physical examination, and imaging studies 1, 7
• Radiological findings may include:
  • Dilated bowel loops on plain abdominal radiographs 1
  • Air-fluid levels 7
  • No transition point (unlike mechanical obstruction) 7
• CT scan can help differentiate between ileus and mechanical obstruction 1

Management

• Initial management includes:

  • Nil per os (NPO) status until bowel function returns 2
  • Intravenous fluid administration to correct dehydration and electrolyte imbalances 2, 6
  • Nasogastric tube placement for decompression in patients with severe distention or vomiting 2, 6
  • Correction of electrolyte abnormalities, particularly potassium and magnesium 2, 6

• Pharmacologic interventions:

  • Avoidance of medications that can worsen ileus (anticholinergics, opioids) 2, 6
  • Alvimopan (μ-opioid receptor antagonist) may accelerate gastrointestinal recovery in postoperative ileus 1, 6
  • Oral magnesium oxide may promote bowel function once oral intake is resumed 2, 6

• Supportive measures:

  • Early mobilization to stimulate bowel function 2, 6
  • Chewing gum to help stimulate bowel function through cephalic-vagal stimulation 2, 6
  • Nutritional support if ileus is prolonged 2, 6

Prevention Strategies

• Minimizing opioid use for pain control 2, 6
• Preferring laparoscopic over open surgical approaches when surgery is necessary 2, 6
• Early mobilization after surgery or illness 2
• Maintaining proper fluid balance without overload 2, 6
• Mid-thoracic epidural analgesia to prevent postoperative ileus 2, 6

Historical Context

• The term "ileus" comes from the Greek word for "twisted" and was originally used to describe sigmoid volvulus 8
• Over centuries, the meaning has evolved from describing various forms of mechanical obstruction to its current usage referring to non-mechanical intestinal obstruction 8