Anorectal manometry is a method of examining the function and coordination of the internal and external sphincters, the pelvic floor, and the rectum by utilizing a manometric device placed in the rectum to cause the anus to contract and relax, and to help differentiate the type of outlet constipation. Introduction The internal and external anal sphincters are the anatomical basis of anal canal pressure. At rest, approximately 80% of anal canal pressure is generated by tension contraction of the internal sphincter and the remaining 20% by tension contraction of the external sphincter. In the case of active contraction of the anal sphincter, anal canal pressure is significantly elevated, and the resulting pressure is formed mainly by contraction of the external sphincter. Therefore, the determination of anal canal pressure in the resting and contracted states provides insight into the functional status of the internal and external anal sphincters. In the determination of anorectal pressure at the same time, can also be measured rectal anorectal inhibitory reflex, the length of the high pressure area of the anal canal (also known as the functional length of the anal canal), the rectal sensory volume and the maximum volume, rectal compliance and other indicators. Patient preparation No special preparation is required. The patient should defecate on his/her own 1 or 2 hours before the examination so as not to have feces in the rectum which may affect the examination. At the same time, do not carry out enema, rectal diagnosis, anoscopy, so as not to interfere with the sphincter function and rectal mucosa and affect the test results. The examiner should debug the instrument beforehand, and some necessary supplies during the examination, such as sterilized gloves, syringes, paraffin oil, toilet paper, cloth pads, etc., should be placed in a convenient place so that they can be accessed at any time. Methods of operation The patient lies on the left side, firstly, the balloon or probe is placed in the anal canal to measure the anal canal resting pressure and maximum systolic pressure, then the balloon is sent into the rectal pot belly to measure the rectal resting pressure. The catheter was connected to a drag device to measure the functional length of the sphincter. The catheter was replaced with a double-bladed catheter, with the large bladder placed in the abdominal pot, and the small bladder (or probe) placed in the anal canal, and the large bladder was rapidly inflated with 50-100 resistance, and the anal canal pressure dropped and the time course was greater than 30 seconds for a positive anorectal inhibitory reflex. Clinical significance Anal incontinence patients anal tube resting pressure and systolic blood pressure decreased significantly, the length of the anal tube high pressure zone becomes shorter or disappears; Rectal anal tube around the irritating lesions, such as anal fissure, inter-sphincter abscess, etc., can cause the anal tube resting pressure increased; Congenital megacolon patients rectal anal tube inhibitory reflex disappeared, rectal prolapse patients the reflex can be lack of or retarded; Megarctal patients with rectum sensory capacity, maximum volume and compliance significantly Increased rectal sensory volume, maximal volume and compliance in patients with megarectum; Inflammatory diseases of the rectum, tissue fibrosis after radiotherapy can cause a decrease in rectal compliance. Anorectal manometry can also provide objective indicators for preoperative condition and pre and postoperative anorectal sphincter function evaluation. Such as anal fissure patients preoperative anorectal manometry examination, the resting pressure is obviously elevated in the internal sphincter cut off, can achieve better results, otherwise the effect is not good; anal incontinence sphincter repair or shaping patients, in the preoperative and postoperative anorectal manometry examination, can be observed after the operation anal tube pressure rebound and high-pressure area recovery, for the judgment of the clinical effectiveness of providing objective basis.