Can the portion of the external anal sphincter (EAS) that was divided during a fistulotomy be strengthened?

Can the Divided External Anal Sphincter Be Strengthened After Fistulotomy?

The divided external anal sphincter (EAS) after fistulotomy cannot be meaningfully strengthened through exercise or rehabilitation, but the healed tissue undergoes progressive fibrosis that creates mechanically stronger scar tissue than the original inflammatory tract, and pelvic floor exercises can optimize remaining sphincter function to restore continence in most patients within 6-12 months. 1

Understanding the Healing Process

The question of "strengthening" the divided sphincter requires distinguishing between the structural integrity of healed tissue versus functional recovery of continence:

Tissue Remodeling Creates Structural Strength

• The healed fistulotomy tract undergoes complete epithelialization and progressive fibrosis over 6-12 months, creating tissue that is mechanically stronger than the original chronic inflammatory fistula tract it replaces. 1
• This remodeled fibrotic scar tissue provides superior structural integrity compared to the diseased tissue, though it is not the same as intact sphincter muscle. 1
• The American Society of Colon and Rectal Surgeons rates this evidence as high quality, confirming that once fully healed, the remodeled tissue provides durable structural integrity. 1

The Divided Muscle Itself Cannot Be "Strengthened"

• Full continence is seldom achieved even in the best-case scenario due to scar tissue formation and denervation injury from the original fistulotomy. 2
• The divided sphincter muscle fibers do not regenerate or hypertrophy in response to exercise—what was cut remains cut. 2
• Complete restoration of normal sensation may not be achievable given the extent of sphincter division, even when continence is preserved. 3

Functional Recovery Through Pelvic Floor Rehabilitation

While you cannot strengthen the divided muscle itself, you can optimize the function of the remaining intact sphincter complex:

Immediate Post-Operative Phase (0-3 Months)

• Incontinence is commonly present immediately after fistulotomy and should not be alarming during the early healing phase, as it typically resolves with tissue recovery. 1
• Pelvic floor muscle training (Kegel exercises) should be initiated immediately after catheter removal or in the immediate postoperative period. 1
• Patients should perform 50 pelvic contractions daily for one year postoperatively. 4

Mid-Term Recovery (3-6 Months)

• Continence improvement generally begins between 3 and 6 months post-surgery, especially when pelvic floor exercises are started promptly. 1
• In one study of 101 patients with low anal fistulas, incontinence occurred in 20% postoperatively but improved completely in half and partially in the other half with regular Kegel exercises. 4
• Mean incontinence scores that deteriorated significantly after fistulotomy became comparable to preoperative levels with consistent pelvic floor exercises. 4

Long-Term Stabilization (6-12 Months)

• Most patients achieve their final continence status by 12 months after fistulotomy, with the recovery curve plateauing thereafter. 1
• Persistent, significant incontinence beyond 12 months is generally regarded as the patient's new baseline rather than a sign of ongoing recovery. 1

When to Consider Surgical Sphincter Repair

Critical Caveat: Sphincteroplasty Has Poor Long-Term Outcomes

Sphincteroplasty performed years after a low transsphincteric fistulotomy carries substantial risks and delivers disappointing long-term results, with only 28% of patients maintaining continence at 40 months and a predicted median time to relapse of just 5 years. 2

Specific Indications and Timing

• If there is no meaningful improvement in continence after 6 months despite conservative measures (pelvic floor exercises, bowel management), consideration of early surgical intervention is appropriate. 1
• Sphincteroplasty is primarily reserved for women with postpartum fecal incontinence, not for post-fistulotomy sphincter defects. 2
• Immediate reconstruction of the anal sphincter after fistulectomy can be considered at the time of initial surgery in selected high-risk patients, with 80% maintaining continence at 24 months follow-up. 5

Alternative Approaches to Consider First

• Sacral nerve stimulation offers the advantage of being reversible and adjustable compared to sphincteroplasty, though neither demonstrates clear superiority. 2
• Conservative management including dietary modification, bowel management programs, and barrier devices may provide better quality of life than a procedure with a 72% failure rate at 40 months. 2

Adjunctive Medical Management

For Persistent Sphincter Hypertonicity

• Apply topical 0.3% nifedipine with 1.5% lidocaine ointment three times daily for at least 6 weeks to reduce sphincter hypertonicity and promote healing. 3
• Expected symptom relief occurs after 14 days, with sphincter hypertonicity typically improving over 6-12 months. 3
• Oral analgesics (paracetamol or ibuprofen) should be added for severe discomfort episodes. 3

Diagnostic Evaluation if Recovery Stalls

• Anorectal manometry should be performed to quantify current sphincter pressures and compare against expected normal values (mean resting pressure >50 mmHg, maximum squeeze pressure >100 mmHg for males). 3
• Endoanal ultrasound must assess for structural sphincter defects, active inflammation, or fluid collections that could explain persistent symptoms. 3
• Active proctitis is an absolute contraindication to any further surgical intervention and would prevent normal healing. 1, 3

Critical Warnings

Absolute Contraindications to Fistulotomy

• Fistulotomy in the anterior perineum of a female patient should be avoided due to asymmetrical anatomy and the short anterior part of the anal sphincter, which has a high chance of jeopardizing fecal continence. 6
• Patients with prior fistulotomy history require sphincter-preserving approaches to prevent catastrophic incontinence. 1
• For Crohn's disease patients, combined anti-TNF therapy with seton drainage produces better results than either modality alone, and surgical closure should only be attempted in the absence of proctitis. 1

Cutting Setons Are Strongly Contraindicated

• The use of cutting setons is associated with a 57% risk of incontinence due to transection and scarring of the anal sphincter from forced migration, and this technique is therefore strongly disadvised. 6