Updated: 12/15/2021

Paralytic / Adynamic Ileus

Review Topic
  • Snapshot
    • A 47-year-old woman on the surgery floor complains of abdominal pain and bloating. She was admitted for appendicitis and underwent a laparoscopic appendectomy 2 days ago. She reports feeling fine since the surgery and denies any fever, swelling, hematuria, hematochezia, or nausea. Her last bowel movement was 3 days ago and she denies any flatulence. A physical examination is unremarkable except for a lack of bowel sounds.
  • Introduction
    • Clinical definition
      • medical condition characterized by the disruption of the normal coordinated propulsive motor activity (peristalsis) of the gastrointestinal tract without any structural/mechanical obstruction
  • Epidemiology
    • Demographics
      • gastrointestinal/abdominal surgery is the most common cause
    • Risk factors
      • gastrointestinal surgery
      • electrolyte imbalance (e.g., hypokalemia or hypercalcemia)
      • diabetes
      • medications (e.g., opioids or antimuscarinics)
      • spinal cord injury
      • severe illness
      • hypothyroidism
      • acute intermittent porphyria
    • Pathogenesis
      • the degree of intestinal paralysis does not need to be complete but enough to functionally prohibit the passage of food leading to intestinal blockage
      • normal gastrointestinal motility is controlled and facilitated by a complex network of various neural networks and neurohumoral peptides
        • enteric nervous system, which is the intrinsic neural network of the gastrointestinal system
        • extrinsic network consists of the visceral sensory afferents of the vagus, splanchnic, and pelvic nerves as well as the visceral motor efferent of the autonomic nervous system
      • gastrointestinal dysmotility can result from various mechanisms
        • inflammation (e.g., surgery or severe illness)
        • neural reflexes
        • neurohumoral peptides (e.g., certain medications)
  • Presentation
    • Symptoms
      • abdominal pain
        • rarely presents as the colicky pain present in mechanical bowel obstruction
      • nausea
      • vomiting
      • vague discomfort
    • Physical exam
      • abdominal distension
      • lack of bowel sounds on auscultation
        • in contrast to the high-pitched tinkling sounds in mechanical bowel obstruction
      • no abdominal tenderness
  • imaging
    • Abdominal radiograph
      • best initial test
      • supine and upright views
      • positive findings may show dilated loops of bowel without a transition zone, air-fluid levels, and air in the colon and rectum
      • allows for rule out of other causes of abdominal pain (e.g., perforated viscus)
  • Studies
    • Diagnostic testing
      • diagnostic approach
        • diagnosis is often based on clinical presentation followed by rule out of other causes of bowel obstruction
      • studies
        • laboratory studies are to be ordered given the clinical presentation to determine etiology/cause
        • electrolyte panel
          • hypokalemia and hypercalcemia may worsen ileus; hypomagnesemia can lead to hypokalemia
        • creatinine and blood urea nitrogen
          • uremia can lead to ileus
        • liver function tests, amylase, and lipase
          • pancreatitis may lead to ileus
        • thyroid panel
          • hypothyroidism may lead to ileus
  • Differential
    • Mechanical bowel obstruction
      • differentiating factors
        • physical examination will demonstrate high-pitched tinkling and history will often include colicky abdominal pain
    • Pancreatitis
      • differentiating factors
        • although can lead to paralytic ileus, patients with pure pancreatitis will not have dilated bowels on imaging
  • Treatment
    • First-line
      • supportive management
        • NPO or dietary restriction
        • if severe, nasogastric suction with parenteral nutrition
        • IV fluids
      • address underlying etiology
        • remove offending medication if applicable
        • replace electrolytes
      • facilitate bowel movements
        • lactulose
        • erythromycin
        • neostigmine
          • for severe cases thought to have a neurological component (e.g., Oglivie syndrome)
  • Complications
    • Perforation
    • Bowel necrosis/ischemia
    • Peritonitis
    • Hemodynamic instability
    • Death

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