Short Bowel Syndrome (SBS)

Short bowel syndrome is a complex malabsorption disorder characterized by the inability to maintain adequate nutritional status without specialized dietary or parenteral support, due to significant functional or anatomical loss of small intestine length.

Key Points

• Definition: Less than 200cm of functional small bowel
• Primary consequence: Malabsorption of nutrients, fluid, and electrolytes
• Common causes in pediatrics:
  • Necrotizing enterocolitis (most common in neonates)
  • Intestinal atresia
  • Gastroschisis
  • Midgut volvulus
  • Extensive inflammatory bowel disease

Pathophysiological Mechanisms

Anatomical Considerations

• Normal small bowel length in newborns: 250-300cm
• Adult length: 600-800cm
• Critical lengths causing SBS:
  • <100cm in neonates
  • <200cm in adults

Adaptive Response

• Intestinal adaptation phases:
  • Acute phase (0-4 weeks)
  • Adaptation phase (2-24 months)
  • Maintenance phase (beyond 24 months)
• Structural changes:
  • Villous hyperplasia
  • Crypt deepening
  • Bowel dilation
  • Muscular hypertrophy

Clinical Presentation

Common Symptoms

• Diarrhea (hallmark symptom)
• Dehydration
• Failure to thrive
• Malnutrition
• Fatigue

Physical Examination Findings

• Growth parameters below normal
• Signs of specific nutrient deficiencies:
  • Angular stomatitis (B vitamin deficiency)
  • Peripheral edema (protein deficiency)
  • Skin changes (zinc/essential fatty acid deficiency)
  • Rickets (Vitamin D deficiency)
• Signs of dehydration
• Abdominal surgical scars

Diagnostic Approach

Initial Evaluation

• Complete history:
  • Surgical history
  • Remaining bowel length
  • Presence of ileocecal valve
  • Continuity of bowel
• Laboratory studies:
  • Complete blood count
  • Comprehensive metabolic panel
  • Prothrombin time
  • Vitamin D, B12 levels
  • Zinc, selenium levels
  • Iron studies

Imaging

• Upper GI series with small bowel follow-through
• CT enterography
• MR enterography

Management Strategies

Nutritional Support

• Parenteral Nutrition:
  • Initial management
  • Calculated based on requirements
  • Regular monitoring of complications
• Enteral Nutrition:
  • Continuous feeds initially
  • Specialized formula selection
  • Gradual advancement

Medications

• Antidiarrheal agents:
  • Loperamide
  • Diphenoxylate
• Acid suppression
• Growth factors (teduglutide)
• Vitamin and mineral supplementation

Surgical Options

• Intestinal lengthening procedures:
  • STEP procedure
  • Bianchi procedure
• Intestinal transplantation

Complications

Short-term Complications

• Fluid and electrolyte imbalances
• Catheter-related infections
• Central line-associated thrombosis
• D-lactic acidosis

Long-term Complications

• Parenteral nutrition-associated liver disease
• Metabolic bone disease
• Growth failure
• Small bowel bacterial overgrowth
• Renal stones