Small Intestine: Pneumatosis Intestinalis

Pneumatosis Definitions

• Pneumatosis Intestinalis – Gas Within the Bowel Wall of Small & Large Intestine
  • Also Known as Pneumatosis Cystoides Intestinalis or Intramural Gas
• Gastric Pneumatosis – Gas Within the Wall of the Stomach

Pathogenic Theories

• Pathogenesis Likely Multifactorial
• Mechanical – Gas Dissects into the Bowel Wall
• Bacterial – Gas Produced by Bacteria that Have Migrated into Submucosal Tissue
• Biochemical – Excessive Gas Produced by Bacteria within Lumen Increases Pressure & Forces Gas into Submucosal Tissue
• Pulmonary – Gas Leakage Through Alveoli Travels into the Retroperitoneum & Localizes within the Bowel Mesentery

Causes/Associations

• Primary/Idiopathic (15%)
• Secondary/Pathologic (85%)
  • COPD – The Most Common Association
  • Intestinal Ischemia
  • Necrotizing Enterocolitis
  • Crohn’s Disease
  • Cystic Fibrosis
  • Asthma
  • Infection
  • Immunodeficiency/AIDS
  • Steroids

Radiographic Findings

• Most Common Site: Jejunum
• Appearance: Gas (Liner or Cystic) within Mucosa, Submucosa or Subserosa
  • Subserosa More Common in Small Intestine
  • Submucosa More Common in Large Intestine
  • *Linear vs Cystic Morphology is Not Predictive of Clinically Worrisome Pathology
• Associated Findings Suggestive of Ischemia:
  • Portal Venous Gas (Although 30% of Portal Venous Gas is Idiopathic)
  • Decreased Mural Contrast-Enhancement

Clinical Correlation

• Most Are Clinically ASx
• Complications:
  • Obstruction
  • Intussusception
  • Ulceration & GI Bleed
  • Pneumoperitoneum from Rupture of Subserosa Cysts
• Management Based on Etiology & Presentation
• Severity:
  • 60% Have Benign Disease
  • 40% Have Pathologic Disease Requiring Surgical Intervention
• Strongest Predictor of Pathologic Cause Requiring Surgery: Lactate > 2.0 mg/dL