In Hirschsprung's disease, the aganglionic segment is always contiguous and begins from the internal anal sphincter. The agangliosis results from failure of migration of neural crest cells. Most commonly, what is the extent of the aganglionic segment?

• A Rectosigmoid aganglionosis — most common (~75% of cases) ✓
• B Long-segment aganglionosis (splenic flexure to rectum) — most common
• C Ultra-short segment (internal sphincter only) — most common
• D Total colonic aganglionosis — most common

Explanation

Hirschsprung's disease occurs due to failure of craniocaudal migration of neural crest-derived ganglion cells, which always arrests proximally, producing a contiguous aganglionic segment from the internal sphincter proximally. Rectosigmoid involvement accounts for approximately 75% of cases (short-segment disease). Long-segment disease (above sigmoid) occurs in ~20% of cases, and total colonic aganglionosis in ~5%. Diagnosis is confirmed by suction rectal biopsy showing absent ganglionic cells and hypertrophic nerve trunks on calretinin/acetylcholinesterase staining.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.