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Gastroenterology & Hepatology

Internal Anal Sphincter Achalasia (Rectoanal inhibitory reflex absent)

ICD-10 Code
K59.8_1

Internal Anal Sphincter Achalasia (Rectoanal inhibitory reflex absent) - Clinical guidelines.

Clinical Presentation & Protocol

Patient Usually Complains Of

Patient presents with chronic refractory constipation, sensation of incomplete evacuation, and straining. Symptoms are unresponsive to laxatives and dietary modification. No history of Hirschsprung disease, but clinical suspicion for internal anal sphincter (IAS) achalasia is high given the absence of the rectoanal inhibitory reflex (RAIR) on anorectal manometry.

Clinical Examination Findings

Digital rectal examination (DRE) reveals increased resting anal tone with paradoxical contraction upon attempted defecation. Anorectal manometry confirms elevated resting pressure and complete absence of the rectoanal inhibitory reflex (RAIR) upon rectal balloon distension. Perianal skin is intact; no evidence of fissures or hemorrhoids.

Treatment Protocol

Initial management includes botulinum toxin type A injection into the internal anal sphincter to induce chemical sphincterotomy. If refractory, consider surgical internal sphincterotomy or pneumatic dilation. Monitor for fecal incontinence post-procedure.

Detailed clinical guide coming soon.