What is pseudoobstruction?

What is Pseudoobstruction?

Pseudoobstruction is a clinical syndrome characterized by symptoms and signs of intestinal obstruction—including abdominal distension, pain, nausea, and vomiting—occurring in the absence of any mechanical blockage of the bowel lumen. 1

Key Distinguishing Features

Pseudoobstruction exists in two fundamentally different forms that must be distinguished:

Acute Pseudoobstruction (Adynamic Ileus/Ogilvie's Syndrome)

• Temporary and reversible disorder of intestinal motility that typically resolves within days 1
• Characterized by diffuse dilation of intestinal loops with air-fluid levels on imaging, but no transition point distinguishing it from mechanical obstruction 1
• Presents with acute abdominal distension, absent bowel sounds, nausea, vomiting, and absence of flatus or bowel movements 1
• Common triggers include post-abdominal surgery, trauma, sepsis, metabolic disorders (especially hypokalemia), endocrine disorders (hypothyroidism), and medications (particularly opioids and anticholinergics) 1, 2
• Generally resolves spontaneously or with conservative treatment addressing the underlying cause 1
• Critical complication: intestinal perforation carries approximately 21% mortality 3, 4

Chronic Intestinal Pseudo-Obstruction (CIPO)

• Chronic syndrome persisting >6 months with recurrent or continuous symptoms of intestinal obstruction 1
• Represents a persistent failure of intestinal propulsion despite absence of mechanical blockage 5
• Frequently requires long-term nutritional support and carries significant morbidity 1

Clinical Presentation Patterns

The presentation varies based on the underlying pathophysiology:

Myopathic Pattern

• Chronic abdominal pain, marked abdominal distension and bloating 5
• Early satiety, recurrent nausea and high-volume vomiting (may be feculent) 5
• Alternating diarrhea and constipation 5
• Progressive weight loss and protein-energy malnutrition without treatment 5
• High risk of pulmonary aspiration from large-volume vomiting 5

Neuropathic Pattern

• Similar severe abdominal pain after food as myopathy 5
• Abdominal distension often absent and plain radiographs may appear normal 5
• Hyperactive gut with uncoordinated, strong contractions despite normal bowel diameter 5

Diagnostic Approach

The diagnosis is established through a systematic process:

Initial Suspicion

• Plain abdominal radiographs showing dilated small and large bowel without transition point 5
• CT/barium follow-through/MR enterography used to exclude mechanical obstruction 5
• In practice, diagnosis often presumed after several laparotomies have excluded physical obstruction 5

Confirmatory Testing

• Small bowel manometry is the logical investigation for confirming pseudoobstruction 5
• In acute forms: temporary absence of contractile activity 1
• In chronic forms: persistent propulsive failure with absence of migrating motor complexes (MMC) and possible abnormal giant contractions 1
• Radioisotopic studies document slow transit through affected bowel segments 5, 1

Identifying Underlying Cause

• Blood tests for metabolic (potassium, magnesium), endocrine (thyroid), and systemic disorders 5
• Auto-antibodies, especially antineuronal antibodies 5
• Testing for mitochondrial disorders, connective tissue diseases (scleroderma), and other systemic conditions 5, 1

Pathophysiological Classification

CIPO can be classified based on the affected tissue layer:

• Myopathy: smooth muscle cell abnormalities causing lack of propulsive strength 1, 6
• Neuropathy: abnormalities of extrinsic/intrinsic nervous supplies causing powerful but uncoordinated contractions 1, 6
• Secondary forms: due to systemic diseases like scleroderma, connective tissue disorders, diabetes, or neurological conditions 1, 2

Clinical Significance and Prognosis

• CIPO represents a major cause of intestinal failure requiring specialized multidisciplinary management 1, 7
• Patients with myopathy have poorer prognosis than those with neuropathy 1
• Mortality rate reaches 10% at 2 years in severe cases 1
• High risk of progressive malnutrition, repeated unnecessary surgeries, and complications from long-term parenteral nutrition 8, 7

Critical Pitfall

Avoid unnecessary laparotomy: The key clinical challenge is recognizing pseudoobstruction to prevent repeated, useless, and potentially dangerous operations in patients whose symptoms mimic mechanical obstruction 6. Early imaging with CT to exclude transition points and consideration of manometric studies can prevent this common error 5.