What are the causes of sigmoid volvulus?

Causes of Sigmoid Volvulus

The primary causes of sigmoid volvulus are anatomical predisposition (particularly dolicho-sigmoid with a narrow mesenteric base), chronic constipation, high-fiber diet, and frequent use of laxatives, which collectively create conditions for the sigmoid colon to twist around its mesenteric axis. 1

Anatomical Factors

• Dolicho-sigmoid: The most commonly cited predisposing factor, characterized by:

  • Elongated sigmoid colon on a narrow mesenteric base
  • High and wide meso-sigmoid with a narrow root
  • Creates mechanical conditions favorable for twisting 1

• Ethnic variations: Significant anatomical differences exist:

  • Africans have longer sigmoid colons and narrower meso-sigmoid roots
  • This explains higher prevalence in the "volvulus belt" (Africa, South America, Russia, Eastern Europe, Middle East, India, Brazil) 1

• Congenital vs. acquired: While anatomical predispositions are clear, it remains uncertain whether they are congenital or acquired over time 1

Patient-Related Risk Factors

• Age and gender patterns:

  • In Western countries: Primarily affects elderly males (>70 years)
  • In endemic regions: Different demographic pattern suggesting possibly distinct clinical entities 1

• Medical conditions:

  • Diabetes
  • Neuropsychiatric disorders (leading to reduced autonomy)
  • Chronic constipation
  • Megacolon (particularly in younger patients) 1

• Associated conditions in younger patients:

  • Hirschsprung's disease
  • Chagas disease
  • Congenital anomalous fixation of the colon 2

• Environmental factors:

  • Institutional placement
  • Prolonged bed rest
  • High-fiber diet
  • Frequent laxative use 1

Pathophysiological Mechanism

• Twisting mechanism:

  • Normal physiological twisting up to 180° can occur
  • Torsion beyond 180° leads to complications (obstruction, ischemia, necrosis)
  • Counterclockwise direction occurs in 70% of cases for unknown reasons 1

• Vicious cycle of progression:

  • Initial twisting → colonic distension → increased intraluminal pressure
  • Decreased capillary perfusion → mural ischemia
  • Aggravated by meso-colic vessel occlusion from mechanical compression
  • Early mucosal ischemia → bacterial translocation → increased gas production
  • Further distension → worsening ischemia if not promptly addressed 1

• Fibrosis development:

  • Meso-sigmoid fibrosis (seen in 86% of operated patients)
  • Result of reversible ischemia rather than a cause
  • Occurs in relapsing forms of volvulus 1

Clinical Implications

• Epidemiology:

  • Third most common cause of colonic obstruction globally (after cancer and diverticulitis)
  • Represents 13-42% of intestinal obstructions in endemic regions
  • Accounts for 10-15% of large bowel obstructions in the USA 1

• Spontaneous resolution:

  • Occurs in approximately 2% of cases 1
  • Not reliable as a management strategy due to high recurrence risk

• Special populations:

  • Pregnancy: Rare but poses significant risk to mother and fetus
  • Pediatric cases: Exceedingly rare, often associated with congenital conditions 2

Understanding these causes is essential for appropriate management, as definitive treatment typically requires surgical intervention to prevent recurrence rates of 45-71% after endoscopic decompression alone 3.