Force in the anal canal and anal continence.

Contribution of Posture to Anorectal Manometric Measurements: Are the Measurements in Left-Lateral Position Physiologic?

“…1 Anorectal manometry forms an essential component of the triple assessment for fecal incontinence. [2][3][4][5][6][7][8][9] This, along with endoanal ultrasound and pudendal nerve studies, is performed routinely in most treatment centers. Traditionally, anorectal physiology is performed with patients in the left-lateral position, despite the fact that incontinence happens mostly in the erect position.…”

“…Traditionally, anorectal physiology is performed with patients in the left-lateral position, despite the fact that incontinence happens mostly in the erect position. [2][3][4][5][6][7][8][9] Dynamic changes occur within the pelvis with variations in posture. For example, changes in the anorectal angle (secondary to puborectalis tone) have been documented with postural changes, and this angle is thought to be important in the maintenance of normal continence.…”

New method of measuring forces in the anal canal.

“…A Valsalva manoeuvre was used as an effective and reasonably controlled method of producing an increase in intraabdominal pressure. It has been shown that there is an accurate correlation between expiratory pressure and intrarectal pressure during a Valsalva manoeuvre (Collins et al, 1967). As with the zeppelin-shaped force gauge used previously there is relatively little increase in force measured at any of the points in the anal canal during the Valsalva manoeuvre.…”

“…Each force gauge was calibrated by applying a force of 6 g weight to the midpoint of each platform and adjusting the amplification so that the recorded trace moved 4 cm. Like previous force gauges used (Collins et al, 1967;Wankling et al, 1968) each cantilever responded only to radial force, so radial force acting at 16 separate sites in the anal canal could be measured. A 12-channel ultraviolet light recorder was used so the output from a maximum of 12 strain gauges could be recorded at any one time.…”

“…The function of the anal sphincters has been measured using many different techniques, from large balloons (Denny-Brown and Robertson, 1935;Schuster, Hendrix, and Mendeloff, 1963) to small balloons or open-ended tubes (Duthie and Watts, 1965;Harris and Pope, 1965;Phillips and Edwards, 1965), and more recently a small force gauge (Collins, Duthie, Shelley, and Whittaker, 1967). Each unit records the effect of sphincter function at a single position in the anal canal and each must be moved up and down the anal canal in order to obtain a picture of the function of the whole length of the sphincter.…”