Can anal stretching and dilation cause long-term damage to the rectum?

1. Historical context: why the debate exists

Anal stretch was a common operative treatment in the 1960s and through early surgical literature, but by the 1970s it fell out of favor as lateral internal sphincterotomy was adopted for being more precise and (arguably) less injurious; surgical reviews explicitly recommended abandoning blind manual stretch because of clear risks to continence seen in older series ^[4]. That history colors current interpretations: many modern proponents of dilation emphasize standardized, measured techniques to avoid the uncontrolled stretching that produced harms in earlier eras ^{[4] [7]}.

2. What animal and mechanistic studies show about extreme stretching

Controlled laboratory work demonstrates a biologic mechanism for lasting injury: in an animal model, stretching the external sphincter beyond certain thresholds produced ischemic necrosis and histologic muscle damage, with correlated loss of contractile pressure—direct evidence that severe overstretch can irreversibly injure sphincter muscle ^{[1] [2]}. Those results establish plausibility: if human procedures produce comparable overstretch, structural damage and functional loss can follow.

3. Human studies: objective damage versus symptomatic outcomes

Human imaging and manometry studies paint a mixed picture. Endosonographic follow-up after dilatation for fissure-in-ano identified sphincter defects in more than half of patients in one series, yet relatively few reported frank fecal incontinence—showing that structural damage does not always translate into severe symptoms ^[3]. Other cohorts and randomized trials report acceptable morbidity, majority patient satisfaction, and often transient minor incontinence (flatus or liquid stool) that frequently improves over weeks to months, especially when standardized dilators or measured diameters are used ^{[5] [6] [8]}.

4. Modern techniques and clinical nuance: dose, method, patient selection

Recent literature emphasizes that "how" dilation is done matters: staged, gradual, or balloon methods with standardized diameters and intraoperative measurement appear less traumatic than blind manual four-finger stretches and may reduce incontinence risk ^{[4] [7]}. Several centers report long-term follow-up after controlled manual dilatation with defined limits (for example, a 35 mm cap) and systematic manometry/clinical checks, but follow-up is often voluntary and heterogeneous across studies, limiting generalizability ^[7].

5. Balancing benefits and harms; where the evidence leaves uncertainty

For some indications—chronic fissure or as adjunct to procedures—dilation can relieve symptoms and reduce pain, but the trade-off includes a measurable risk of sphincter injury and transient or, less commonly, lasting incontinence ^{[6] [8]}. The evidence base has limitations: older studies used uncontrolled techniques, newer studies are single-center or observational with variable follow-up, and objective damage does not map neatly to patient-reported dysfunction ^{[4] [7] [3]}. Alternative viewpoints exist: advocates of dilation stress symptomatic benefit and lower wound-related complications compared with sphincterotomy, while critics point to objective sphincter damage and historical higher incontinence rates with manual stretch ^{[4] [5]}.

6. Practical implications inferred from the literature

When dilation is considered, the safest interpretation of current evidence is to treat the procedure as one with real potential for sphincter injury: risk is minimized by standardized, measured techniques under appropriate clinical oversight, careful patient selection, informed consent about incontinence risk, and objective follow-up ^{[4] [7] [6]}. Where studies disagree or lack data, the literature does not support categorical claims that dilation is harmless; nor does it say every dilation causes permanent damage—outcomes depend on method, extent of stretch, and patient factors ^{[1] [3]}.