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What is an anorectal manometry test?
Find out what anorectal manometry is and how it can help assess the sphincter muscle function
Anorectal manometry: what it is for
Anorectal manometry is a specialized test used for the accurate diagnosis of problems relating to the functioning of anal sphincters and rectal sensitivity.
This examination can thus be useful for the diagnosis of many anorectal conditions, such as fecal incontinence, constipation, defecation disorders, anal pain and tenesmus.
Rectal manometry is also used before and after surgical procedures on the anorectal area, e.g. for the treatment of anal fissures or hemorrhoids. In some cases, these procedures may involve the risk of anal continence.
Measurement of sphincter’s pressures simulating defecation, at rest or on contraction gives essential information on the ability to manage the passage of feces or intestinal gases and other incontinence disorders. The physician assesses this data taking into account factors, such as gender, age, childbirths, and/or other diseases.
When emptying the bowels, the sphincter muscles should relax to allow feces and gases to pass through. Likewise, when trying to delay defecation, the sphincter muscles must contract enough to prevent bowel leakage. It is important that the sphincter muscles exert the right amount of pressure at rest to avoid involuntary leakage, while sleeping or coughing, for instance.
Any factor that may alter one of these delicate mechanisms might affect our quality of life, sometimes significantly. Therefore, it is vital to accurately identify the cause of the disorder in order to determine the most suitable treatment.
Anal manometry allows the study of the sphincter’s functions when straining, at rest and when squeezing and to identify any abnormalities. In particular, anorectal manometry helps to identify:
- incontinence issues linked to the inability of the muscles to contract correctly
- difficulties and problems in defecating due to the incomplete opening and release of the sphincter muscles
To date, there are no alternative diagnostic tests to obtain this type of data.
When symptoms are associated to problems in the functioning of the anal sphincter muscles, anorectal manometry is an essential diagnostic procedure to obtain details on the causes and mechanisms behind these disorders.
Anorectal manometry: preparation
To prepare for the examination, the physician normally requests an enema, especially for patients suffering from constipation.
The Anorectal Manometry procedure is generally carried out in the physician’s office and does not require anesthesia, fasting, discontinuation of any current treatments nor any dietary changes required in the days leading up to the procedure. The patient does not need to be accompanied by anyone when manometry is performed because it does not require any drugs to be administered.
Traditional anorectal manometry: procedure
Traditional manometry is an outpatient diagnostic procedure that has been used for decades to examine the mechanisms involved in emptying the bowels and in retaining feces.
The procedure lasts approx. 20-30 minutes and it uses bulky and fairly complex equipment. The equipment also includes an air or water perfusion system, special catheters, and a system for obtaining data.
The patient lies down on their left side, brings their knees up to their chest and leans their buttocks on the edge of the table (commonly called the Sims Position). When the patient is ready, the specialist gently inserts a catheter with a small balloon into the anal canal up to the rectum.
The physician then inflates the balloon with air or water to dilate the anorectal canal which simulates the sensation of distension and the later stimulus to empty the bowels.
This is how the physician can detect the pressure that the patient exerts at different points of the anal canal and the factors behind conditions such as fecal incontinence and sphincter hypertonia.
Modern anorectal manometry: features and advantages
In recent years, technological advances have led to significant developments in traditional anorectal manometry. In fact, diagnostic systems are available that enable this procedure to be more accurate and more comfortable for the patient.
Today several medical centers perform anal manometry by means of a small and highly sensitive probe that the physician inserts into the anal canal to measure sphincter muscles pressure. The probe is connected to a compact device that measures changes in pressure in real time.
The small probe is inserted to a depth of approximately 10 cm and the examination does not last more than 5 minutes. Thus, the procedure time is reduced and the patient feels minimal discomfort.
An increasing number of medical centers use this new diagnostic system; it is precise and easy to perform and interpret. This allows the patient to undergo a very useful examination with the least amount of discomfort.