What is pneumatosis?

Pneumatosis Intestinalis: Definition, Diagnosis, and Management

Pneumatosis intestinalis is defined as the presence of gas within the wall of the gastrointestinal tract, most commonly found in the large bowel, but can also occur in the small bowel, with gas present in either the subserosal or submucosal layer of the intestine. 1

Clinical Significance and Etiology

Pneumatosis intestinalis (PI) represents a spectrum of conditions ranging from benign to life-threatening. It can be categorized into two main types:

1. Life-threatening pneumatosis intestinalis: Associated with bowel ischemia, infarction, necrotizing enterocolitis, neutropenic colitis, volvulus, and sepsis. This represents a surgical emergency. 2

2. Benign pneumatosis intestinalis: Also known as pneumatosis cystoides intestinalis, characterized by gas-filled cysts in the submucosa and subserosa that may not require surgical intervention. 3

Common causes include:

• Bowel necrosis: Due to mesenteric ischemia, infarction, or sepsis
• Mucosal disruption: From over-distention, peptic ulcer, obstruction, trauma, or iatrogenic causes
• Immunocompromised states: In patients on steroids, chemotherapy, radiation therapy, or with AIDS
• Pulmonary causes: COPD, asthma, cystic fibrosis, barotrauma
• Cryptogenic: Unexplained causes 2

Radiological Findings

Pneumatosis intestinalis is primarily identified through imaging studies:

• CT Angiography (CTA): The diagnostic study of choice for suspected mesenteric ischemia with PI. It has a sensitivity of 93% and specificity of 100% for diagnosing acute mesenteric ischemia. 4

• Key radiological findings:

  • Bowel loop dilatation
  • Pneumatosis intestinalis (gas in bowel wall)
  • Free intraperitoneal fluid
  • Portal venous gas (a particularly ominous sign)
  • Mesenteric venous thrombosis 4

• Appearance patterns: PI may appear as linear or cystic collections of gas within the bowel wall 2

Clinical Evaluation

When pneumatosis intestinalis is detected, clinical assessment is crucial to determine severity:

• Concerning symptoms: Abdominal pain out of proportion to physical exam findings, especially in elderly patients
• Laboratory findings: Metabolic acidosis, elevated lactate, leukocytosis, hemoconcentration, elevated amylase levels, and abnormal liver enzymes may indicate acute mesenteric ischemia 4
• Physical examination: May be normal in benign cases or show signs of peritonitis in severe cases 1

Management Approach

The management of pneumatosis intestinalis depends on the clinical context:

Emergency Surgical Intervention Indicated When:

• PI is associated with acute mesenteric ischemia
• Signs of bowel necrosis are present
• Patient has peritoneal signs
• Presence of portal venous gas with clinical deterioration
• Evidence of bowel perforation 4, 3

Conservative Management Appropriate When:

• Incidental finding without abdominal symptoms
• Normal physical examination
• Absence of other signs of bowel wall distress
• Immunocompromised patients with stable vital signs 5

Important Considerations

1. Clinical significance varies widely: The same radiological finding can represent either a benign condition or a life-threatening emergency. 1

2. Context matters: In oncology patients receiving chemotherapy, PI may be an incidental finding that resolves without surgical intervention. 5

3. Associated findings: The presence of portal venous gas strongly suggests bowel infarction and typically indicates a poor prognosis. 4

4. Delay in diagnosis: Every 6 hours of delay in diagnosis (specifically delay in CTA) doubles mortality in cases of acute mesenteric ischemia with PI. 4

5. Benign vs. life-threatening: Distinguishing between benign pneumatosis cystoides intestinalis and life-threatening pneumatosis intestinalis is challenging but critical for appropriate management. 3

In summary, pneumatosis intestinalis is a radiological finding that requires careful clinical correlation. While it can represent a surgical emergency in the setting of mesenteric ischemia or bowel necrosis, it may also be a benign finding in certain populations. Prompt recognition and appropriate triage of patients with PI is essential to optimize outcomes.