Anatomical disruption and length-tension dysfunction of anal sphincter complex muscles in women with fecal incontinence.

BACKGROUND: Anal sphincter complex muscles, the internal anal sphincter, external anal sphincter, and puborectalis muscles, play an important role in the anal continence mechanism. Patients with symptoms of fecal incontinence have weak anal sphincter complex muscles; however, their length-tension properties and relationship to anatomical disruption have never been studied. OBJECTIVE: This study aimed to assess the anatomy of the anal sphincter complex muscles with the use of a 3-dimensional ultrasound imaging system and to determine the relationship between the anatomical defects and the length-tension property of external anal sphincter and puborectalis muscles in women with incontinence symptoms and in control subjects. DESIGN: Severity of anal sphincter muscle damage was determined by static and dynamic 3-dimensional ultrasound imaging. The length-tension property was determined by anal and vaginal pressure with the use of custom-designed probes. PATIENTS: Forty-four asymptomatic controls and 24 incontinent patients participated in this study. MAIN OUTCOME MEASURES: The anatomical defects and length-tension dysfunction of anal sphincter complex muscles in patients with fecal incontinence were evaluated. RESULTS: The prevalence of injury to sphincter muscles is significantly greater in the incontinent patients than in the controls. Eighty-five percent of patients but only 9% controls reveal damage to ≥2 of the 3 muscles of the anal sphincter complex. Anal and vaginal squeeze pressures increased with the increase in the probe size (length-tension curve) in the majority of controls. In patients, the increase in anal and vaginal squeeze pressures was either significantly smaller than in controls or it decreased with the increasing probe size (abnormal length-tension). LIMITATIONS: We studied patients with severe symptoms. Whether our findings are applicable to patients with mild to moderate symptoms remains to be determined. CONCLUSIONS: The length-tension property of the external anal sphincter and puborectalis muscles is significantly impaired in incontinent patients. Our findings have therapeutic implications for the treatment of anal incontinence.

Dynamic assessment of the vaginal high-pressure zone using high-definition manometery, 3-dimensional ultrasound, and magnetic resonance imaging of the pelvic floor muscles.

OBJECTIVE: We used a novel technique, high-definition manometry (HDM) that utilizes 256 tactile sensitive microtransducers to define the characteristics of vaginal high-pressure zone. STUDY DESIGN: Sixteen nullipara asymptomatic women were studied using HDM, transperineal 2-dimensional dynamic ultrasound and dynamic magnetic resonance (MR) imaging. RESULTS: Vaginal high-pressure zone revealed higher contact pressures in anterior and posterior directions compared with lateral directions, both at rest and squeeze. At rest, anterior pressure cluster is located 10 mm cephalad to posterior pressure cluster; with squeeze the latter moves in the cranial direction by 7 mm. Ultrasound and MR images revealed that the anorectal angle moves cephalad and ventrally during squeeze. Cephalad movement of posterior pressure cluster during squeeze is similar to the cranial movement of anorectal angle. CONCLUSION: We propose that the vaginal high-pressure zone represents the constrictor function and cranial movement of the posterior pressure cluster represents the elevator function of pelvic floor. HDM may be used to measure the constrictor and elevator functions of pelvic floor muscles.

Pelvic floor anatomy and applied physiology.

Pelvic floor muscles have two major functions: they provide support or act as a floor for the abdominal viscera including the rectum; and they provide a constrictor or continence mechanism to the urethral, anal, and vaginal orifices (in females). This article discusses the relevance of pelvic floor to the anal opening and closure function, and discusses new findings with regards to the role of these muscles in the vaginal and urethra closure mechanisms.