How does hemorrhoidectomy affect anal sensation and how long do the sensory changes typically last?

Effect of Hemorrhoidectomy on Anal Sensation

Hemorrhoidectomy does not impair anal sensation or sphincter function in the long term, and sensory discrimination can actually improve after surgery in patients with preoperative sensory deficits. 1

Immediate Post-Operative Period (First 5–30 Days)

• Maximum resting pressure (MRP) increases significantly during the first 5 days after Milligan-Morgan hemorrhoidectomy due to post-operative inflammation and sphincter spasm, but this represents a temporary physiological response rather than permanent dysfunction. 2

• By 30 days post-operatively, MRP values return to baseline preoperative levels, though they remain slightly elevated compared to healthy controls during this early recovery phase. 2

• Ultra-slow wave activity (USWA)—a marker of sphincter coordination—shows mild increases during the first month after surgery but does not indicate permanent functional impairment. 2

Medium-Term Recovery (6 Months)

• At 6 months, anal sensation testing demonstrates that the ability to discriminate between air and warm water (a validated measure of mucosal sensory function) improves in patients who had preoperative sensory impairment, indicating restoration rather than loss of sensory capacity. 1

• Maximum resting pressure normalizes to levels comparable with healthy subjects by 6 months, with resolution of the sphincter hypertension that was present preoperatively due to hemorrhoidal disease. 2

• Three-dimensional transanal ultrasonography confirms no structural changes in internal anal sphincter (IAS) width at 6 months (mean 2.1 mm before and after surgery), demonstrating preservation of sphincter anatomy. 1

Long-Term Outcomes (12 Months and Beyond)

• At 12 months after hemorrhoidectomy, MRP values are significantly lower than preoperative measurements and equivalent to healthy controls, confirming complete resolution of the sphincter hypertension that was secondary to hemorrhoidal disease. 2

• The rectoanal inhibitory reflex (RAIR)—a critical marker of IAS neurological function—remains intact in 90–95% of patients at 6 months, with no significant changes from baseline. 1

• Maximum squeeze pressure (MSP), which reflects external anal sphincter function and voluntary continence control, shows no significant change at any time point after surgery (mean 178 mmHg preoperatively vs. 174 mmHg at 6 months). 1

• Continence scores do not differ significantly at 6 months or beyond, and no patients develop new-onset fecal incontinence when standard closed hemorrhoidectomy is performed with appropriate technique. 1, 3

Key Mechanism: Secondary vs. Primary Sphincter Dysfunction

• Sphincter hypertension in hemorrhoid patients is secondary to the disease itself rather than a primary pathological process, which explains why surgical removal of hemorrhoids normalizes rather than impairs sphincter function. 4

• Patients with advanced-stage (grade III–IV) hemorrhoids demonstrate significantly elevated resting anal pressure preoperatively (only 25% of men and 30% of women have normal baseline pressures), and this hypertension resolves after hemorrhoidectomy. 4

• The most rapid normalization of sphincter overactivity occurs after stapled hemorrhoidopexy (Longo procedure) and Hemoron application, while Milligan-Morgan technique shows the longest recovery period but still achieves complete normalization by 12 months. 4

Clinical Implications and Common Pitfalls

• Lateral internal sphincterotomy should never be added to hemorrhoidectomy, as sphincter hypertension is secondary to hemorrhoidal disease and resolves spontaneously after hemorrhoid removal; adding sphincterotomy increases incontinence risk without providing benefit. 5, 4

• Avoid excessive anal dilation or retraction during surgery, as these maneuvers are the primary mechanisms causing sphincter injury and the 2–12% incidence of post-operative incontinence reported in some series. 5, 6

• When incontinence occurs after hemorrhoidectomy, it typically reflects pre-existing comorbidities (prior obstetric injury, perianal infection, Crohn's disease) rather than isolated surgical injury, and thorough investigation is warranted before attributing symptoms solely to the procedure. 6

• Standard closed hemorrhoidectomy under adequate local anesthesia with appropriate submucosal dissection preserves anal sphincter function both clinically and manometrically when performed correctly. 3