In a man who has undergone a low‑grade fistulotomy with reduced internal anal sphincter (IAS) tone, does resting IAS tone contribute to arousal buildup and orgasm?

Resting Internal Anal Sphincter Tone Does Not Contribute to Arousal or Orgasm in Men

The internal anal sphincter (IAS) plays no role in sexual arousal buildup or orgasm in men; reduced IAS tone after fistulotomy will not affect sexual function. 1

Physiologic Basis for Functional Separation

IAS Function Is Limited to Continence

• The IAS provides approximately 70–80% of resting anal canal pressure (averaging 73 ± 27 cm H₂O in healthy individuals) through involuntary smooth muscle tone that maintains passive fecal continence. 1, 2
• IAS tone is regulated exclusively by autonomic innervation: sympathetic fibers increase tone to maintain continence, while parasympathetic fibers mediate the rectoanal inhibitory reflex during defecation—neither pathway participates in sexual arousal or ejaculatory mechanisms. 1

Sexual Function Relies on Voluntary Pelvic Floor Muscles

• Sexual arousal and orgasm are driven by voluntary contraction of the external anal sphincter, puborectalis, and bulbospongiosus muscles via somatic pudendal nerve pathways (S2–S4), not by autonomic control of the IAS. 1
• The bulbocavernosus muscle (part of the external anal sphincter complex) acts as a "suction-ejection pump" during ejaculation by compressing the penile bulb and dorsal penile vein, functions that are entirely independent of IAS tone. 3

Clinical Evidence from IAS Dysfunction

Outcomes After IAS Injury or Dysfunction

• Reduced IAS tone—whether from surgical sphincterotomy, structural injury, or neurogenic dysfunction—results in passive fecal incontinence (leakage of stool and flatus at rest) without affecting sexual arousal, erection, or orgasm. 1
• After lateral internal sphincterotomy for chronic anal fissure, approximately 1–10% of patients experience minor flatus incontinence, but any postoperative sexual dysfunction is attributable to external sphincter or pelvic-floor involvement, not to changes in IAS pressure. 1, 4

Autonomic Neuropathy Does Not Impair Sexual Function via IAS

• Autonomic neuropathy associated with diabetes mellitus or Parkinson's disease can diminish resting IAS tone and cause fecal incontinence, but these conditions do not produce sexual dysfunction through loss of IAS function. 1, 5

Common Clinical Pitfall

Misattribution of Pelvic Floor Tension

• Pelvic floor muscle tension during sexual activity should not be conflated with IAS function; the IAS remains in its baseline involuntary state throughout sexual activity and does not contribute to arousal buildup or orgasmic response. 1
• Any sexual dysfunction following anorectal surgery is more likely related to pain-mediated reflex inhibition, damage to voluntary pelvic floor muscles (external anal sphincter, bulbocavernosus), or psychological factors, not to reduced IAS tone. 3

Specific Answer to the Clinical Scenario

In a man who has undergone low-grade fistulotomy with reduced IAS tone:

• The reduced IAS tone may cause minor passive fecal incontinence (occasional leakage of flatus or liquid stool at rest). 1, 4
• Sexual arousal and orgasm will remain intact because these functions depend on voluntary contraction of the external anal sphincter and bulbospongiosus muscles via pudendal nerve pathways, which are anatomically and functionally separate from the IAS. 1
• If sexual dysfunction develops postoperatively, investigate pain, external sphincter injury, or psychological factors—not IAS tone. 3