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Ileus

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Overview

Ileus describes the disruption of gastrointestinal (GI) motility that is not associated with mechanical obstruction and most commonly presents 2-3 days following surgery. It is a diagnosis of exclusion after bowel obstruction has been ruled out.

Since GI motility is mediated by neurologic and hormonal factors, ileus often occurs following causes of physiological stress, such as surgery (especially bowel surgery), GI diseases, sepsis, and metabolic abnormalities. These stresses can disrupt these factors and lead to ileus.

Causes

Post-operative ileus

Ileus may develop following surgery, however, motility returns in the GI tract 48 hours after surgery. Some patients may develop prolonged post-operative ileus (also known as paralytic ileus) which is defined as the following occurring ≥4 days post-surgery:

  • Vomiting
  • Abdominal distention
  • Intolerance of oral feeding
  • Absence of opening the bowels or flatus

Other causes

Other causes may include:

  • Ileus secondary to systemic illness:
  • Narcotic ileus:
    • Ileus secondary to opioid use

Risk Factors

  • Surgery, especially GI surgery
  • Acute severe illness (e.g. sepsis, acute pancreatitis, GI diseases)
  • Electrolyte imbalances
  • Diabetes mellitus
  • Severe hypothyroidism
  • Increased age
  • Medications (e.g. opioids)
  • Spinal cord injury

Presentation

Features suggesting ileus include:

  • Diffuse abdominal pain
  • Nausea and vomiting
  • An inability to tolerate oral feeding
  • Abdominal distention and bloating
  • Lack of bowel movements, particularly constipation and lack of passing flatus
  • Bowel sounds are absent on auscultation

Differential Diagnoses

Mechanical bowel obstruction

  • May present similarly to ileus, but constipation is a prominent feature
  • Auscultation may reveal high-pitched ‘tinkling’ bowel sounds instead of absent sounds in ileus

Investigations

  • Full blood count:
    • May show increased white cells suggesting infection
  • U&Es including calcium, phosphate, and magnesium:
    • May show electrolyte derangements
    • Elevated urea and creatinine may be present in dehydrated patients 
  • Arterial blood gases:
    • To look for acid-base disturbances (e.g. acidosis in intestinal ischaemia)
  • Abdominal x-ray:
    • Although less sensitive than a CT, this is often done initially
    • Can rule out other pathologies such as bowel perforation, which would show gas under the diaphragm
  • Abdominal CT:
    • The diagnostic test of choice

Management

Management involves:

  • Making the patient nil-by-mouth and giving IV fluids
  • Inserting a nasogastric tube if the patient is vomiting
  • This can help with decompressing the gut
  • Correction of the underlying cause 
  • Reducing opioid analgesia use and if possible, switching to an alternative
  • Total parenteral nutrition may be considered in prolonged ileus

Complications

  • Prolonged stay in hospital post-surgery
  • Aspiration pneumonia:
    • This may occur in patients who are vomiting

Prognosis

  • Postoperative ileus usually resolves with conservative management within 4 days

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