Equipment The specifics of the equipment used for the procedure will ultimately depend on the type of manometry and the manufacturer of the device. Nonetheless, most share some common features. * Catheter - used to insert the probe and balloon into the anorectum. The catheter may be water-perfused, solid-state or air-charged. * Probe - contains sensors whose number and arrangement depend on the manufacturer and type of manometry * Sensors - records pressures and transmits them back to the controller software * Balloon - used to assess sensation when inflated with air. Most balloons used are non-latex and are manufactured to expand to 400 ml. A separate catheter with a water-inflatable balloon may be used to conduct a balloon expulsion test. * Software - receives data from sensors. Data is then used to calculate values to be used for analysis and to provide visual feedback. Technique In 2019, the International<unk>  Physiology Working Group (IAPWG) released a standardized testing protocol for the use of<unk> . One of the goals of this protocol was to standardize procedural techniques to better facilitate meaningful data sharing. This protocol is the most recent published guideline for<unk>  since the one published in 2002 which was not widely adopted. Preparation Fasting is not a requirement for this procedure. Patients are informed as to how the procedure is performed, its benefits and risks. Risks include the possibility of developing discomfort, pain, minor bleeding, dizziness or a rare perforation. In the testing room, the patient is placed on their left side with their knees bent. A digital rectal exam is then preformed prior to the procedure to evaluate initial anatomy and function, check for stool, and to assess patient's understanding of the verbal instructions employed during the procedure. Tests<unk>  is often performed alongside a rectal sensory test (RST) and a balloon expulsion test (BET) The RST is preformed after the manometry while the BET may be performed immediately prior to the manometry or subsequent to the RST. The total time to conduct all three tests is 15 to 20 minutes. Manometry This test takes approximately 10 minutes. With the use of a lubricant, an<unk>  catheter is introduced into the anus. The catheter is advanced until the base of the balloon is above the anal canal by and the most distal sensor is below the anal verge. In order, the following maneuvers are then preformed: +Descriptions and purpose of maneuvers preformed during manometry test Maneuver Description Purpose Length of Time Stabilization No instruction Allow return to baseline 3 minutes Rest Patient asked to rest Measure resting pressure, detect presence of ultraslow waves 60 seconds Short squeeze Squeeze as if preventing expulsion of feces or flatus Measure squeeze pressure 3 five second squeezes each separated by 30 seconds of recovery Long squeeze Squeeze as if preventing expulsion of feces or flatus Measure squeeze pressure 30 seconds followed by a 60-second interval of recovery Cough Cough once Measure changes in pressure during cough 1 cough followed by a 30-second interval of recovery followed by another 1 cough Push Push as if defecating Measure changes in pressure during defecation, detect presence of RAIR 3 fifteen second pushes separated by 30 seconds of recovery RST During the rectal sensory test, air is placed into the catheter balloon and slowly inflated either continuously or step-wise. The patient is asked to verbalize when they first sense the balloon, when the urge to defecate is first present and when they can no longer tolerate the balloon. BET To perform the balloon expulsion test, a catheter with a balloon on its tip is introduced into the patient's anorectum. The balloon is then distended to 50ml with water. Patients are then instructed to transfer from lying on their side to sitting on a toilet. Next, patients are asked to push out the balloon as if they are defecating. The time it takes for the expulsion of the balloon is then recorded. Analysis Resting pressure The anal resting pressure is the recorded pressure within the anus during muscle relaxation. After insertion of the catheter, a short amount of time is allowed for the muscles to relax. Afterwards, pressures are recorded over 60 seconds. The maximum resting pressure is the highest pressure reached during this time period, while the mean resting pressure is the average pressure during this time period. In healthy individuals, women, especially older women, have an average lower anal resting pressures than men. Squeeze pressure The anal squeeze pressure is the recorded pressure within the anus during a voluntary contraction of the external anal sphincter. Similar to resting pressures, squeeze pressures in healthy women are lower than healthy men. If using high-definition<unk> , asymmetry in squeeze pressures can also be measured. Change of pressure during defecation During defecation, the pressure in the anorectum should increase while the external anal sphincter should relax. If the pressure difference during defecation does not increase sufficiently, it may indicate poor propulsive force. Additionally, inadequate relaxation of the sphincter during defecation is another abnormal finding. Another method to assess changes during defecation is to calculate an<unk>  gradient (or defecation index) in one of two ways. The<unk>  gradient is either calculated as a difference (rectal pressure - anal pressure) or as a ratio (rectal pressure / anal pressure). A positive difference or a ratio over 1 indicates normal findings. Abnormal findings on manometry does not definitively indicate illness as a significant number of healthy individuals have been found to have abnormal results. Values recorded during a defecation trial are influenced by a number of factors including the degree of patient involvement in defecation efforts. Rectoanal Inhibitory Reflex (RAIR) In healthy individuals, in the process of defecating, the internal anal sphincter will reflexively relax. The lack of a rectoanal inhibitory reflex may indicate either the absence or the non-functionality of certain muscle or nerve structures involved in proper defecation. Sensation Patients are assessed on their<unk>  sensory perception via the inflation of a balloon. As the balloon is inflated, its volume is recorded at certain milestones: initial sensation of the equipment, start of the sensory urge to defecate and the point of maximum discomfort. An increased level of sensation has been noted in disorders such as fecal incontinence, while a decreased level of sensation has been seen in individuals with dyssynergic defecation. Interpretation As part of the 2020 IAPWG consensus manuscript, the group published the newly created London Classification for Disorders of<unk>  Function which aimed to standardize the interpretation of<unk>  findings. The London Classification divided disorders into 4 parts: +London Classification for Disorders of<unk>  Function Part Disorder 1 Disorder of the RAIR 2 Disorders of anal tone and contractility 3 Disorders of rectoanal coordination 4 Disorders of rectal sensation Under each part, there are a list of diagnosis that are made based on manometry findings. For example, under part 2 (Disorders of anal tone and contractility), listed manometric diagnoses include: anal hypotension, anal hypertension, anal hypercontractility and combined anal hypertension and hypercontractility. Findings are also divided into: major findings, minor findings and inconclusive findings. Major findings are findings that are not present in healthy patient such as rectoanal areflexia, Minor findings are findings that are more commonly found in patients with<unk>  disease compared to healthy patients, while inconclusive findings are findings that may be present in both groups.
Anorectal manometry
High resolution manometry
Endoanal ultrasound
Endorectal coil magnetic resonance imaging
Sigmoidoscopy
Transrectal ultrasonography
Transrectal biopsy
Rectal examination