What is Pneumatosis Intestinalis?
Pneumatosis intestinalis (PI) is a radiological sign—not a disease—defined as the pathological presence of gas within the submucosa or subserosa of the bowel wall, appearing as linear or cystic collections on imaging. 1, 2
Clinical Significance and Interpretation
PI represents a spectrum of conditions ranging from benign, asymptomatic findings to life-threatening emergencies requiring immediate surgical intervention. 1 The critical task is distinguishing between these two extremes based on clinical context and associated imaging findings.
Life-Threatening vs. Benign Forms
The presence of peritonitis, hemodynamic instability, septic shock, or bowel infarction mandates immediate surgical exploration regardless of other considerations. 3, 4
Key indicators of life-threatening PI include: 5, 3
- Signs of peritonitis (guarding, rebound tenderness, rigidity)
- Portal venous gas (strongly suggests bowel infarction and carries poor prognosis)
- Free intraperitoneal air
- Hemodynamic instability or septic shock
- Rectal bleeding with abdominal pain
- Lactic acidosis (reflects advanced tissue hypoperfusion)
In contrast, approximately 60% of PI cases represent benign disease, particularly when patients lack peritoneal signs and maintain stable vital signs. 5
Diagnostic Approach
CT scan is the gold standard for detecting PI and determining its underlying cause. 3 CT provides superior sensitivity compared to plain radiography and allows assessment of critical associated findings. 3, 2
Essential CT findings to evaluate: 5, 3
- Bowel wall thickness (>4mm is abnormal)
- Pattern of wall enhancement (reduced or absent enhancement suggests ischemia)
- Bowel dilatation
- Portal venous gas
- Free intraperitoneal fluid or air
- Mesenteric stranding
The combination of multiple ischemic findings (intestinal dilatation and thickness, reduction/absence of visceral enhancement, pneumatosis, and portal venous gas) reflects irreversible ischemia. 5
Common Clinical Settings
PI occurs in several distinctive contexts: 1, 6
Neonatal/Pediatric:
- Necrotizing enterocolitis in premature infants
Adult populations:
- Chronic obstructive pulmonary disease
- Immunosuppression (transplant recipients, chemotherapy, steroid therapy)
- Ischemic bowel disease
- Inflammatory bowel disease (particularly Crohn's disease with asymmetric wall thickening)
- Mechanical bowel obstruction
- Progressive systemic sclerosis
- Critically ill ICU patients on mechanical ventilation or vasopressors
Primary benign pneumatosis cystoides intestinalis (PCI) represents approximately 15% of cases and is typically asymptomatic. 7
Management Algorithm
Immediate Surgical Intervention Required: 3, 4
- Peritoneal signs present
- Hemodynamic instability
- Septic shock
- Evidence of bowel necrosis on imaging
Treatment: Emergency laparotomy with resection of necrotic bowel segments. 3
Conservative Management Appropriate: 3
- Absence of peritoneal signs
- Stable vital signs
- No evidence of bowel ischemia
Treatment approach:
- Bowel rest with nasogastric decompression
- Broad-spectrum antibiotics if bacterial translocation suspected
- Close clinical and biochemical monitoring
- Temporarily withhold immunosuppressive medications in inflammatory bowel disease patients
Special Consideration for Oxygen Therapy:
Symptomatic patients with benign PI may benefit from oxygen therapy and/or antibiotics, though evidence is largely anecdotal. 1
Critical Pitfalls to Avoid
Do not mistake PI for malignancy or polyposis—this leads to inappropriate surgical intervention in benign cases. 1
Do not delay imaging with CT when mesenteric ischemia is suspected—laboratory tests including lactate have limited early diagnostic value, as 25% of patients with acute mesenteric ischemia have normal initial labs. 8 Metabolic acidosis and elevated lactate indicate advanced disease when bowel injury has already progressed significantly. 8
Do not perform colonoscopy when perforation is suspected or confirmed—this worsens pneumoperitoneum and peritoneal contamination. 4
In critically ill ICU patients on vasopressors with unexplained abdominal distension or gastrointestinal bleeding, maintain high suspicion for non-occlusive mesenteric ischemia (NOMI)—symptoms may be undetectable in 25% of sedated patients. 5, 8