What does muscular hypertrophy in the sigmoid colon indicate?

Muscular Hypertrophy in the Sigmoid Colon: Diagnostic Significance

Muscular hypertrophy in the sigmoid colon primarily indicates diverticular disease or sigmoid volvulus, both conditions associated with chronic increased intraluminal pressure and altered colonic wall structure. 1

Key Diagnostic Implications

Diverticular Disease

• Muscular hypertrophy is a characteristic finding in diverticular disease with a reported specificity of 98% 1
• Represents a response to longstanding elevated intraluminal pressures that contribute to the underlying pathophysiology of diverticulosis
• Important findings:
  • Not true cellular hypertrophy but rather thickening of muscle layers 2
  • No evidence of muscle cell hyperplasia despite the appearance of thickened musculature 2
  • Associated with increased elastin content (>200% compared to controls) in the taeniae coli 3

Sigmoid Volvulus

• Muscular hypertrophy is commonly found in surgical specimens from sigmoid volvulus patients 4
• Associated with:
  • Fibrosis of the meso-sigmoid (seen in 86% of operated patients) 1
  • Hypertrophy of the submucosa, muscularis propria, and nerve plexuses 4
  • Evidence of chronic ischemic changes including thrombosed and recanalized veins 4

Clinical Correlation

For Diverticular Disease

• CT findings typically include:
  • Pericolonic fat stranding
  • Bowel wall thickening
  • Presence of diverticula
  • Muscular hypertrophy as a specific sign 1

For Sigmoid Volvulus

• Anatomical predispositions include:
  • Dolicho-sigmoid (elongated sigmoid colon on a narrow mesenteric base)
  • Increased length of meso-sigmoid
  • Increased width of meso-sigmoid
  • Increased luminal circumference 1
• Risk factors:
  • Chronic constipation
  • High-fiber diet
  • Frequent laxative use
  • Diabetes
  • Neuropsychiatric issues
  • Institutional placement
  • Prolonged bed rest 1

Rare Presentations

In rare cases, sigmoid muscular hypertrophy alone can cause colonic obstruction without evidence of inflammation, fibrosis, or neoplasia 5. This presentation may initially be misdiagnosed as acute diverticulitis.

Diagnostic Approach When Muscular Hypertrophy Is Identified

1. CT scan with IV contrast is the preferred imaging modality (89% positive diagnostic yield for sigmoid volvulus) 6

   • Look for associated findings: diverticula, wall thickening, fat stranding
   • Assess for complications: perforation, abscess, fistula formation

2. Consider endoscopic evaluation

   • To rule out malignancy (present in up to 30% of sigmoid strictures initially thought to be diverticular) 6
   • To assess for associated mucosal changes

3. Watch for complications

   • In diverticular disease: bleeding, diverticulitis, abscess, perforation, stricture
   • In sigmoid volvulus: obstruction, ischemia, necrosis with perforation

Management Implications

When muscular hypertrophy is identified in the sigmoid colon, management should be directed at the underlying condition:

• For diverticular disease: Medical management with fiber supplementation, antibiotics for acute diverticulitis, and surgical intervention for complications

• For sigmoid volvulus:

  • Urgent flexible endoscopic decompression as first-line treatment (success rate 60-95%)
  • Definitive surgical treatment (segmental colectomy or resection with primary anastomosis) to prevent recurrence, especially important as recurrence rates after successful endoscopic detorsion without surgery are high (43-75%) 6

Pitfalls to Avoid

• Failing to recognize muscular hypertrophy as a potential marker of chronic pathology
• Missing associated ischemic changes that may affect surgical outcomes
• Not extending resection margins beyond the hypertrophic segment in surgical cases, which may lead to anastomotic complications 4
• Overlooking the possibility of malignancy as a cause of sigmoid stricture 6