What is manual anal dilation, particularly for a patient with a history of anal fissure repair surgery?

What is Manual Anal Dilation?

Manual anal dilation is an outdated and abandoned surgical technique that should never be performed for anal fissure treatment due to unacceptably high rates of permanent incontinence (up to 10%) and temporary incontinence (up to 30%). 1

Historical Context and Technique

Manual anal dilation was historically used to treat internal anal sphincter hypertonicity in patients with chronic anal fissures. 1 The procedure involved:

• Placing the index fingers of both hands into the anus under anesthesia
• Forcefully stretching the anal sphincter in multiple directions
• Dilating the sphincter to reduce its resting tone and theoretically improve blood flow to the fissure 1

Why This Procedure Was Abandoned

The practice was definitively abandoned due to its severe complications and inferior outcomes compared to other treatments. 1

Unacceptable Incontinence Rates

• Temporary incontinence occurs in up to 30% of patients 1, 2
• Permanent incontinence develops in up to 10% of patients 1, 2
• Sphincter damage occurs in more than 65% of patients undergoing the procedure, even when they remain continent 3
• Female patients appear particularly vulnerable to incontinence complications 4

Poor Efficacy

• Manual dilation has significantly higher rates of fissure persistence compared to internal sphincterotomy 5
• The procedure failed to successfully treat 26 out of 46 anal fissures (57% failure rate) in one retrospective series 4
• Manual anal stretch carries both higher risk of treatment failure AND higher risk of incontinence compared to sphincterotomy 5

Superiority of Alternative Treatments

• Internal sphincterotomy demonstrates superior healing rates with lower complication rates 1, 5
• Modern topical treatments (0.3% nifedipine with 1.5% lidocaine) achieve 95% healing rates without any incontinence risk 2, 6

Current Guideline Recommendations

The World Society of Emergency Surgery (WSES) and American Association for the Surgery of Trauma (AAST) strongly recommend AGAINST the use of manual dilatation in patients with acute anal fissure (strong recommendation based on moderate quality evidence). 1

Important Distinction: Controlled Anal Dilation

While traditional manual anal dilation is contraindicated, newer controlled or staged dilation techniques using standardized measurements and balloon devices have emerged. 1 These modern techniques:

• Use precise, measurable dilatation to specific diameters (typically 35mm) 7
• Show healing rates comparable to sphincterotomy with near-zero incontinence rates 1
• Require specialized equipment and standardized protocols 7
• Are NOT the same as traditional manual anal dilation 1

However, even for these controlled techniques, current guidelines state that insufficient evidence exists to make recommendations for their use in acute anal fissure settings. 1

Clinical Implications for Post-Surgical Patients

For a patient with a history of anal fissure repair surgery who underwent manual anal dilation:

• Monitor closely for any signs of fecal or flatus incontinence, as sphincter damage may have occurred even if the patient is currently continent 3
• Sphincter defects are present in 65% of patients post-procedure, with internal sphincter damage being most common 3
• If incontinence symptoms develop, consider endoanal ultrasound to assess for sphincter defects 3
• Current treatment for any recurrent fissure should utilize topical calcium channel blockers (0.3% nifedipine/1.5% lidocaine) rather than repeat dilation 2, 6

Common Pitfall to Avoid

Never confuse historical manual anal dilation with modern controlled dilation techniques—they are fundamentally different procedures with vastly different safety profiles. 1, 7 The term "anal dilation" without the qualifier "controlled" or "staged" refers to the abandoned manual technique that should never be performed. 1