Lateral Internal Sphincterotomy: Procedure, Benefits, Risks, Recovery and Alternatives

Lateral Internal Sphincterotomy (LIS) has long been viewed as the gold standard surgical intervention for chronic anal fissure, especially when nonoperative management fails. However, like all medical procedures, it offers a balance of benefits, risks, and alternatives worth considering. This article provides a comprehensive, evidence-based overview to help patients and clinicians make informed decisions.

Lateral Internal Sphincterotomy: The Procedure

LIS is a surgical technique designed to treat chronic anal fissures by reducing the high resting pressure of the internal anal sphincter. By partially dividing the sphincter muscle, the procedure relieves pain and promotes healing of the fissure. The operation can be performed under local, regional, or general anesthesia, with patients often going home the same day.

Step	Description	Purpose	Source(s)
Incision	Small cut at the lateral aspect of the anus	Access sphincter	3 5 8 16
Sphincter Division	Partial cut of internal anal sphincter	Lower resting pressure	4 5 10 13 15
Closure	Often left open or closed depending on technique	Heal with minimal scarring	3 16
Technique	Open or closed (subcutaneous) approach	Varies by surgeon	8 16

Table 1: Key Steps in Lateral Internal Sphincterotomy

Surgical Methods: Open vs. Closed

There are two main surgical approaches: open and closed LIS. Open LIS involves a direct incision under visualization, while closed LIS uses a subcutaneous track to divide the sphincter without fully opening the tissue above. Both methods are effective, but open LIS may have a slightly higher risk of complications such as infection or delayed wound healing, whereas closed LIS might be associated with a marginally higher recurrence risk but lower incontinence rates 8 16.

Calibrated and Partial Division

The extent of sphincter division can be tailored to individual needs, often guided by manometry (pressure measurement). For mild hypertonia, less of the sphincter is divided, reducing incontinence risk, while severe hypertonia may require a larger division 5 13. Some surgeons perform a "calibrated" LIS, customizing the length of the cut to the fissure’s apex or just below it, further minimizing the risk of sphincter dysfunction 5 13.

Outpatient and Anesthesia Options

LIS is typically performed as an outpatient procedure. Local anesthesia is often sufficient, making it a convenient and accessible option for most patients 2 3 15.

Benefits and Effectiveness of Lateral Internal Sphincterotomy

LIS is renowned for its high success rate and rapid relief of symptoms. It is the treatment of choice when conservative therapy fails, with multiple studies confirming its efficacy and patient satisfaction.

Benefit	Description	Success Rate	Source(s)
Healing	Rapid fissure healing	90–99%	1 4 10 16 17
Pain Relief	Fast reduction in pain	High	1 9 13
Recurrence	Low rate of fissure recurrence	2–8%	8 9 10 16
Patient Satisfaction	High long-term satisfaction	96–98%	8 10 15 17

Table 2: Effectiveness and Benefits of LIS

High Healing and Rapid Pain Relief

Most patients experience dramatic improvement in pain within the first week after surgery, and fissure healing rates as high as 99% have been reported 1 4 10 16 17. The median time to complete healing is typically three weeks 10.

Low Recurrence Rates

LIS offers very low recurrence rates—generally 2–8%—making it superior to most non-surgical and alternative surgical treatments 8 9 10 16. In cases where fissures do recur, they are often manageable with conservative measures 10.

Quality of Life and Satisfaction

Surveys show 96–98% of patients are satisfied with their results after LIS, reporting significant improvements in quality of life 10 15 17. The rapid symptom relief and durable healing contribute to these high satisfaction rates.

Effectiveness in Complex Cases

LIS is effective even for surgically recurrent fissures and in cases where other interventions have failed, maintaining high success and satisfaction rates 15.

Risks and Side Effects of Lateral Internal Sphincterotomy

While LIS is generally safe and effective, it carries some risk—most notably, the potential for fecal incontinence. Understanding these risks is crucial for informed consent and optimal patient selection.

Risk/Side Effect	Description	Frequency	Source(s)
Fecal Incontinence	Loss of flatus or stool control (minor–major)	3–45% (mostly minor)	8 10 11 13 16 17
Minor Complications	Pain, pruritus, abscess, bleeding	5–16%	4 6 8 10
Persistent Symptoms	Ongoing pain or unhealed fissure	<5%	5 8 13
Permanent Defects	Rare permanent incontinence	~1–3%	10 11 13

Table 3: Risks and Side Effects of LIS

Fecal Incontinence: The Main Concern

• Incidence: Minor degrees of incontinence (gas or soiling) are reported in 3–9% of patients in long-term studies, though some studies report transient symptoms in up to 45% immediately post-op 8 10 11 13 16 17.
• Severity: Most cases are mild and resolve over time; only 1–3% experience persistent or bothersome symptoms 10 13.
• Risk Factors: Female sex, previous obstetric trauma, and excessive sphincter division increase the risk 10 13.

Other Complications

• Minor Issues: Temporary pain, pruritus (itching), delayed healing, wound infection, and minor bleeding can occur, but are generally manageable 4 6 8 10.
• Rare Serious Effects: Permanent or socially significant incontinence is rare, especially with careful surgical technique and patient selection 10 11 13.
• Surgical Technique Matters: Conservative or calibrated LIS approaches lower the risk of incontinence while maintaining efficacy 5 13.

Impact on Quality of Life

Most patients report little to no negative impact on quality of life from minor incontinence. When significant, it can reduce satisfaction, highlighting the importance of individualized risk assessment 11 17.

Recovery and Aftercare of Lateral Internal Sphincterotomy

Recovery from LIS is typically swift, with most patients returning to normal activities within days to weeks. Proper aftercare promotes healing and minimizes complications.

Phase	What to Expect	Duration/Advice	Source(s)
Pain Relief	Rapid reduction post-surgery	1–7 days	1 9
Wound Healing	Complete healing of incision/fissure	2–8 weeks	3 9 10
Activity	Return to normal activities	1–7 days	1 10 15
Complication Monitoring	Watch for infection, bleeding	First 2 weeks	4 8 10

Table 4: Recovery and Aftercare Highlights

Early Recovery: The First Week

• Pain Relief: Most patients experience dramatic pain relief within days 1 9.
• Wound Care: The wound is usually small; daily gentle cleansing and keeping the area dry are recommended 3 9.
• Bowel Movements: Stool softeners and high-fiber diets help prevent straining, which promotes healing and reduces discomfort 9.

Longer-Term Healing

• Incision Healing: The incision and fissure generally heal within 2–8 weeks. Complete resolution of symptoms is typical by this time 3 9 10.
• Return to Activities: Most people resume work and normal routines within a week, though heavy lifting or strenuous exercise may be delayed 1 10 15.
• Follow-up: Regular check-ins ensure healing is on track and complications are caught early 10.

Managing Complications

• Signs to Watch: Persistent pain, fever, significant bleeding, or pus should prompt medical attention 4 8 10.
• Incontinence: Any new or worsening issues with stool or gas control should be reported; most minor cases resolve with time 10 11 13.

Alternatives of Lateral Internal Sphincterotomy

While LIS is highly effective, several alternatives exist, especially for those at higher risk for complications or who prefer to avoid surgery.

Alternative	Description	Effectiveness	Source(s)
Topical Therapy	Nitroglycerin, diltiazem, nifedipine creams	40–60% healing	11 14
Botulinum Toxin (Botox)	Injection to relax sphincter muscle	44–75% healing	7 14
Fissurectomy	Surgical removal of fissure tissue	75–87% healing	1 9 17
Hemorrhoid Treatments	Banding, hemorrhoidectomy for hemorrhoids	Variable	2 6 12

Table 5: Alternatives to LIS

Non-Surgical Options

• Topical Medications: Creams like nitroglycerin or calcium channel blockers relax the sphincter but have lower healing and higher recurrence rates compared to LIS 11 14.
• Botulinum Toxin Injection: Botox temporarily paralyzes the internal sphincter, promoting healing. It is less effective than LIS and has a higher recurrence rate, but carries a lower risk of incontinence—a good option for those at higher risk of sphincter damage 7 14.

Surgical Alternatives

• Fissurectomy: Removing the fissure tissue without cutting the sphincter. It is less effective than LIS, with lower healing rates and similar or even higher incontinence risks in some studies 1 9 17.
• Other Procedures: Hemorrhoid treatments (band ligation, hemorrhoidectomy) are suitable if coexisting hemorrhoids are the primary issue 2 6 12.

Individualized Treatment

Choosing the right approach depends on:

• Patient age and sex
• History of childbirth or prior anorectal surgery
• Severity and duration of symptoms
• Patient preference and risk tolerance

Conclusion

Lateral Internal Sphincterotomy remains the gold standard for chronic anal fissure refractory to conservative therapy. Its high effectiveness and rapid pain relief must be weighed against the risk of (mostly minor and transient) fecal incontinence, especially in at-risk patients. Careful patient selection, calibrated surgical technique, and consideration of alternatives are key to optimal outcomes.

Key Points:

• LIS is highly effective, offering rapid symptom relief and healing in over 90% of cases 1 4 10 16 17.
• Main risk is minor incontinence, most often self-limited; permanent, significant incontinence is rare with careful technique 8 10 11 13 16 17.
• Recovery is typically fast; most patients return to normal life within a week and heal completely within 2–8 weeks 3 9 10.
• Alternatives exist for those at higher risk or not suitable for surgery, but tend to have lower efficacy and/or higher recurrence 7 11 14 17.
• Patient-centered decision-making—considering individual risks and preferences—remains essential for best outcomes.

For anyone facing chronic anal fissure, an open discussion with your healthcare provider about the risks, benefits, and alternatives of LIS is the first step toward lasting relief.