Can a lateral internal sphincterotomy be performed at varying depths of the internal anal sphincter, and how can we determine the actual extent of the IAS division in a patient who had LIS with fissurectomy and hemorrhoidectomy three years ago and now reports pelvic pain and possible incontinence?

Can Lateral Internal Sphincterotomy Be Performed at Varying Depths?

Yes, lateral internal sphincterotomy can and should be performed at varying depths based on the degree of internal anal sphincter hypertonia, with the extent of division ranging from 20% to 60% of the sphincter length depending on manometric findings, and in your case with pelvic pain and possible incontinence three years post-surgery, the actual extent of IAS division can be determined through 3D endoanal ultrasonography combined with anal manometry. 1, 2

Understanding Variable Sphincterotomy Depths

The internal anal sphincter can be divided at different extents during LIS, and this is not an "all-or-nothing" procedure:

Calibrated Sphincterotomy Based on Hypertonia

• Mild hypertonia (50-60 mmHg resting pressure): Only 20% of the internal sphincter length should be divided 1
• Moderate hypertonia (60-80 mmHg): 40% of the sphincter should be divided 1
• Severe hypertonia (>80 mmHg): 60% of the sphincter should be divided 1
• The traditional "full" sphincterotomy divides the IAS up to the dentate line, but this carries higher incontinence risk 3

Critical Safety Threshold in Women

• In women specifically, dividing less than 25% of the total sphincter length (corresponding to less than 1 cm) is associated with significantly better continence outcomes 2
• When more than 25% of the sphincter is divided in women, the risk of continence problems increases substantially 2
• Conservative division (less than full dentate line) achieves 97% healing rates with only 1.7% incontinence to fluid/flatus and 0% fecal incontinence 3

Minimal Sphincterotomy Technique

• The "minimal LIS" approach divides only the fibrotic portion of the internal sphincter, resulting in 0.4% gas incontinence and 1.3% recurrence rates 4
• This technique challenges the traditional view that extensive division is necessary for success 4

Determining the Actual Extent of Your Prior Surgery

Diagnostic Approach

You need 3D endoanal ultrasonography to visualize the sphincter defect and measure what percentage of your IAS was actually divided 2:

• 3D ultrasonography can measure the exact length of the sphincter division and compare it to your total sphincter length 2
• This imaging will show whether you had a conservative (<25%), moderate (25-50%), or extensive (>50%) division 2
• The ultrasound should be combined with anal manometry to measure your current resting anal pressure 1

Interpreting Your Surgeon's Statement

The surgeon's comment that he "didn't have to cut him" likely means one of three things:

1. A conservative/minimal sphincterotomy was performed (20-25% division) rather than a traditional full division to the dentate line 1, 3
2. Only the fibrotic portion was divided using the minimal LIS technique 4
3. The division was tailored to your specific degree of hypertonia rather than a standard extensive cut 1

This does NOT mean no sphincterotomy was performed—the operative note documents LIS was done, but the extent may have been conservative 3

Evaluating Your Current Symptoms

Distinguishing Incontinence from Neuropathic Pain

Your pelvic pain and "possible incontinence" three years post-surgery requires careful differentiation:

• If you have altered sensations, hypersensitivity, or sexual dysfunction WITH intact continence: This represents neuropathic dysesthesia and pelvic floor muscle tension, not structural sphincter failure 5, 6
• If you have actual leakage of stool, liquid, or gas: This represents true incontinence from excessive sphincter division 2, 3

Diagnostic Workup for Your Symptoms

Order the following tests to determine the cause of your symptoms:

1. 3D endoanal ultrasonography to measure the sphincter defect length and identify any occult sphincter injuries from the hemorrhoidectomy 2
2. Anal manometry to measure resting and squeeze pressures—if resting pressure is <30 mmHg, this suggests excessive sphincter division 1
3. Cleveland Clinic Florida (Wexner) incontinence score to quantify the severity of any true incontinence 2

Expected Findings Based on Symptoms

• **Post-operative resting pressure <30 mmHg with true incontinence:** Indicates excessive sphincter division (>25% in women, >40% in men) 1, 2
• Normal continence with altered sensations/pain: Indicates neuropathic component or pelvic floor dysfunction, not structural failure 5, 6
• Sphincter defect >1 cm in women or >25% of total length: Associated with higher incontinence risk 2

Treatment Algorithm for Your Current Symptoms

If True Incontinence Is Confirmed

• Pelvic floor physical therapy 2-3 times weekly with internal and external myofascial release, focusing on sphincter coordination retraining 5, 6
• Biofeedback therapy specifically targeting rectal sensation and internal sphincter coordination 6
• Avoid any additional surgical interventions—these will worsen, not improve, incontinence from over-division 5

If Neuropathic Pain/Dysesthesia Without True Incontinence

• Specialized pelvic floor physical therapy with internal myofascial release is the primary treatment 5, 6
• Topical lidocaine 5% ointment for neuropathic pain control 5, 6
• Gradual desensitization exercises guided by a pelvic floor physical therapist 5
• Warm sitz baths to promote muscle relaxation 5
• Expected improvement over 6-12 months with appropriate therapy 6

Critical Pitfalls to Avoid

• Do not pursue revision surgery or additional sphincter procedures—this will worsen neuropathic symptoms and increase incontinence risk 5, 6
• Never undergo manual anal dilatation—this carries 10-30% permanent incontinence risk and is absolutely contraindicated 7, 5
• Do not perform Kegel exercises if you have pelvic floor tenderness—these will exacerbate muscle tension and spasm 5
• Recognize that hemorrhoidectomy itself can cause sphincter defects in up to 12% of patients through excessive retraction and dilation, independent of the sphincterotomy 8

Why the Combination Surgery Matters

Your operative note shows fissurectomy, hemorrhoidectomy, AND lateral sphincterotomy—this combination is important:

• Hemorrhoidectomy alone causes sphincter defects in up to 12% of patients through excessive retraction during the procedure 8
• Adding LIS to hemorrhoidectomy increases incontinence risk compared to LIS alone 8
• Your symptoms may result from combined sphincter injury from both the hemorrhoidectomy technique and the sphincterotomy extent 8, 2

The 3D ultrasonography will reveal whether you have a discrete sphincterotomy defect, diffuse sphincter thinning from the hemorrhoidectomy, or both 2.