Post-Fistulotomy Hypersensitivity and Urinary Changes: Nerve Injury, Not Hypertension
Your symptoms—hypersensitive fistulotomy scar, dulled urinary stream sensation, and increased urgency with full bladder—are most consistent with pudendal or perineal nerve injury from the surgical procedure, not hypertension. Hypertension does not cause localized perineal hypersensitivity or altered bladder sensation patterns.
Why This Is Nerve Injury
Mechanism of Pudendal Nerve Damage During Fistulotomy
Perineal nerve injury from surgical stretching or direct trauma is a well-documented complication of anorectal procedures, causing denervation of the pelvic floor that modifies sphincter resistance and sensory function 1.
The pudendal nerve provides both motor and sensory innervation to the perineum, external anal sphincter, and portions of the lower urinary tract—surgical manipulation during fistulotomy can directly injure these distal motor and sensory branches 1.
Your hypersensitive scar represents neuropathic pain from injured sensory nerve fibers, a classic sign of peripheral nerve trauma rather than vascular (hypertension-related) pathology 2.
Your Specific Urinary Symptoms Point to Nerve Dysfunction
Dulled sensation of urinary stream indicates impaired sensory afferent signaling from the urethra and bladder neck, which are innervated by pudendal nerve branches 3.
Increased urgency specifically with full bladder suggests altered bladder sensory processing—when sensory pathways are damaged, the brain may receive abnormal afferent signals that are interpreted as exaggerated urgency 4.
This pattern matches incomplete cauda equina syndrome presentations where reduced bladder or urethral sensation co-occurs with urgency 5.
Why This Is NOT Hypertension
Hypertension causes systemic vascular changes but does not produce localized perineal hypersensitivity or focal sensory deficits in specific nerve distributions.
Hypertension-related bladder dysfunction would present as chronic, progressive symptoms affecting detrusor contractility globally—not acute post-surgical changes in specific sensory modalities 6.
Your symptoms appeared after fistulotomy, establishing clear temporal causation with the surgical trauma rather than a pre-existing systemic condition.
Clinical Assessment Required
Immediate Evaluation
Perform anorectal manometry and endoanal ultrasound to assess sphincter integrity and identify any ongoing inflammation or fluid collections that could compress nerves 2.
Measure post-void residual urine volume to determine if you have incomplete bladder emptying, which would indicate more severe pudendal nerve dysfunction affecting detrusor-sphincter coordination 6.
Test perineal sensation systematically using light touch and pinprick in the S2-S4 dermatomes to map the extent of sensory loss or hypersensitivity 5.
Electrophysiologic Testing
Pudendal nerve terminal motor latency studies can objectively document nerve injury and help predict recovery potential 1.
These studies measure conduction velocity in the distal pudendal nerve branches and can distinguish between temporary neuropraxia (which recovers) versus more severe axonal injury 1.
Treatment Approach
For Hypersensitive Scar (Neuropathic Pain)
Apply topical 0.3% nifedipine with 1.5% lidocaine ointment three times daily for at least 6 weeks to reduce sphincter hypertonicity and promote nerve healing—this achieves 95% healing rates for anal wounds 2.
Consider neuropathic pain medications (gabapentin or pregabalin) if topical therapy is insufficient, as your hypersensitivity represents nerve injury pain.
For Urinary Urgency and Altered Sensation
Begin behavioral bladder training by systematically extending intervals between voids, which can help retrain abnormal sensory processing in the brain 6.
Reduce caffeine and manage fluid intake to minimize bladder irritation while nerve healing occurs 6, 7.
If urgency persists beyond 8-12 weeks of behavioral therapy, consider antimuscarinic agents or β3-agonists (e.g., tolterodine, mirabegron) to suppress detrusor overactivity 6.
Specialist Referrals
Refer to a colorectal surgeon with sphincter preservation expertise for comprehensive assessment of sphincter function and nerve injury extent 2.
Refer to a pelvic floor physical therapist for specialized rehabilitation to optimize recovery of both sphincter and bladder function 2.
Prognosis and Timeline
Pudendal nerve injuries from surgical procedures typically resolve within 6 weeks to 3 months if the injury is neuropraxia (temporary conduction block) rather than axonotmesis (axonal disruption) 8.
Complete wound healing requires 6-12 weeks for basic structural integrity, with full nerve and tissue maturation taking 6-12 months 2.
Your dulled urinary sensation may improve as nerve regeneration occurs, but permanent sensory changes can occur if nerve injury was severe 1.
Critical Warning Signs
Development of urinary retention (inability to void, elevated post-void residual >200 mL) would indicate progression to more severe nerve dysfunction requiring urgent urological evaluation 5.
New fecal incontinence or complete perineal numbness would suggest cauda equina syndrome and require emergency MRI imaging 5.
Worsening pain, fever, or purulent drainage from the fistulotomy site could indicate abscess formation requiring surgical drainage 5.