Anorectal Physiology: Test and Clinical Application

Abstract

The physiology of the anorectal region is very complex, and it is only recently that detailed investigations have given us a better understanding of its function. The methods that are used for the evaluation of anorectal physiology include anorectal manometry, defecography, continence tests, electromyography of the anal sphincter and the pelvic floor, and nerve stimulation tests. These techniques furnish a clearer picture of the mechanisms of anorectal disease and demonstrate pathophysiologic abnormalities in patients with disorders of the anorectal region. Therefore, therapeutic recommendations for anorectal disease can be made best when the anatomy and the physiology of the anorectal region are understood.

Pelvic floor functional bowel disorders in gynaecology

“…The internal sphincter muscles account for 52-85% of the pressure in the resting period, with a normal range of 65-85 mmHg. 13 The maximal resting pressure is in the region of 1-1.5 cm above the anal verge. 14 Squeeze pressure is created by contracting the external sphincter muscle and the puborectalis muscle.…”

Anatomy, physiology, and updates on the clinical management of constipation

“…Continence is a manifestation of individual conscious will coupled with intestinal reflexes and is dependent upon functioning anorectal sensation and appropriate interpretations of sensory information (Cho, 2010;McCrea, Miaskowski, Stotts, Macera, & Varma, 2008).…”

“…Defecation is initiated by high amplitude propagated contractions (HAPCs) of the sigmoid colon that push colonic contents into the rectum (Andrews & Storr, 2011;Shelton & Welton, 1997). The rectum is equipped with mechanoreceptors that induce reflexes to communicate to the internal anal sphincter that stool is ready to enter into the anus; if this action is suspended, then other reflexes allow the stool to remain in the rectum until a more appropriate time to defecate is found (Cho, 2010). Stool does not fill the rectum all at once, as the intraluminal pressure would cause the internal anal sphincter to accept the stool suddenly and proceed with defecation immediately; moreover, the rectum fills passively with stool and gradually increases in volume so that the intraluminal pressure remains low and the internal anal sphincter can detect the presence of the stool and sample the rectal contents to determine whether defecation is convenient (Shelton & Welton, 1997).…”

Pelvic floor investigations for bowel dysfunction (part 2): anorectal physiology (manometry)

“…To achieve this, clinicians can use assessment tools, including defaecation proctography, endoanal ultrasound (Hibberts et al, 2018) and anorectal physiology (Bharucha, 2008). clinical © 2019 MA Healthcare Ltd and solid-state (or high-resolution) systems (Cho, 2010):…”

“…Static-another common orientation has 4-8 transducers arrayed evenly along the catheter, either in the same plane or in a spiral around the catheter. The intubated catheter is left in place while measurements of the whole anal canal are taken simultaneously, and it is removed once they are complete (Cho, 2010). Both water-perfused and solid-state systems are operated with a similar technique, dependent on orientation.…”