a protocol for diagnostic evaluation of anorectal disorders is recommended which includes testing for rectal prolapse and for descent of the perineum by having the patient strain while seated on a commode chair , evaluating the external and internal anal sphincters by recording emg with an anal plug , or recording pressures with a perfused catheter or balloon probe , using a rectal balloon to evaluate the maximum tolerable volume of rectal distension and the minimum ( threshold ) volume of a bolus injection which can be subjectively perceived , and arranging with a radiologist to perform a proctogram -- a radiograph of the rectum and anal canal during rest and when the patient strains to defecate -- in order to evaluate the anorectal angle ( puborectalis muscle ) and to detect rectocele and intussusception .
C0224394
internal anal sphincters
C0227411
anal canal