Pneumatosis intestinalis

The presence of gas within bowel wall. A finding which can be either primary or secondary, and not always related to small bowel ischaemia.

Epidemiology

• Uncommon
• Usually occurs 30-60yo

Aetiology

Primary (15%)

• • Benign idiopathic condition
  • Not associated with any other conditions or symptoms
  • Found incidentally

Secondary (85%)

• • COPD
  • Immunocompromised state
  • Post-transplant
  • Leukaemia
  • Lymphoma
  • Vasculitis
  • Collagen vascular disease
  • Chemotherapy or corticosteroids
  • Inflammatory, obstructive or infectious conditions of the intestine
  • Iatrogenic - endoscopy and jejunostomy placement
  • Small bowel ischaemia
  • Diabetes

Pathophysiology

• Multiple gas-filled cysts in the wall of the GIT
  • Can occur anywhere from oesophagus to rectum
  • Most common in jejunum, followed by ileocaecal and colon
• May be located in the subserosa, submucosa, and rarely the muscularis layer
• Vary in size from microscopic to several centimetres
• When it is seen in neonates, is usually associated with necrotising enterocolitis (see topic under 'paeds')
• Gross inspection - cysts resemble cystic lymphangiomas or hydatid cysts
• Theories for pathogenesis
  • Mechanical theory
    • Dissecting gas into the wall, from either within lumen (mucosal tears) or serosa (serosal tears)
    • Could explain association with COPD - coughing
  • Bacterial theory
    • Could result from gas-forming bacteria gaining access to submucosa through mucosal breaks
    • Doesn't sound likely - these cysts are sterile
  • Biochemical theory
    • Luminal bacteria produce excess hydrogen gas through fermentation

Presentation

• Cyst rupture can give rise to pneumoperitoneum
  • One of the few causes of sterile pneumoperitoneum - consider in the patient with free air but no peritonism
• Non-specific symptoms
• Ominous sign when associated with peritonitis, mesenteric gas, or portovenous gas - most likely related to small bowel ischaemia
• Primary disease can give rise to diarrhoea, abdominal pain, abdominal distension, nausea, vomiting, weight loss, and mucus in stools
• Complications
  • Obstruction
  • Volvulus
  • Intussusception
  • Adhesions following cyst collapse

Differential

• Pseudo-pneumatosis intestinalis - a.k.a. string of beads sign, intra-luminal gas masquerading as intra-luminal gas

Assessment

• History and examination
  • Look for underlying aetiology of secondary disease
  • Particularly look for risk of ischaemia - grossly distended, peritonitic
• CT
  • Look for associated findings of ischaemia - PV gas, etc
  • Pneumoperitoneum is not necessarily concerning
• Bloods
  • Usually normal in pneumatosis intestinales

Management

• Indications for exploratory laparotomy - any one of the following
  • Peritonitis
  • Metabolic acidosis
  • Lactate >2
  • PV gas
• Non-op management for all others
  • Antibiotics
  • Elemental diet
  • Reconsider surgery if deterioration or at around a week