Anorectal Manometry and Biofeedback
Jason R. Baker, PhD
Anorectal manometry is a test of anorectal function that can provide useful information about disorders that affect defecation and continence. There are various methods of performing the studies,1,2 and minimum standards of performance have been recommended.3,4 The equipment used to perform anorectal manometry may also be used to provide biofeedback training for patients with constipation due to obstructed defecation and for those with fecal incontinence due to various causes. Before performing anorectal manometry or biofeedback, one should obtain hands-on instruction and supervision from someone experienced in manometry. Manometry training programs are available through some of the companies marketing manometric equipment (Medtronic, Minneapolis, Minnesota; Diversatek, Milwaukee, WI; Laborie, Williston, VT).
Prior to 2007, anorectal manometry was primarily performed using conventional methodology via water-perfused and solid-state catheters with three to six unidirectional sensors. Since 2007, high-resolution and high-definition catheters have become more prevalent to perform anorectal manometry. These catheters include tightly spaced circumferential sensors along a longitudinal axis illustrating a spatiotemporal depiction of the anorectum. Using these contemporary catheter designs, the anorectal manometry duration and resolution have become shorter and greater.5,6 Conversely, the high-resolution and high-definition catheters are more fragile and expensive compared to conventional catheter designs.
2. Fecal incontinence
3. Evaluation prior to biofeedback training for pelvic floor dyssynergia
4. Evaluation prior to biofeedback training for continence strategies
5. Preoperative evaluation before procedures involving the anus and/or rectum such as creation of a pouch, ileoanal anastomosis, and elective sphincteroplasty
Use of latex balloons in individuals with latex allergy.
In general, no preparation is required. If stool is present during a digital rectal examination, a rectal enema should be administered. A latency period of 30 minutes should be employed from the enema administration to the start of anorectal manometry. Patients may continue on their usual medications, and dietary modification is not required. Informed consent must be obtained.
The procedure should be explained to the patient. Afterward, the patient should be asked to change into a hospital gown.
Required equipment includes the following:
1. A probe. Both water-perfused, solid-state probes, and closely spaced sensor catheters are commercially available for anorectal manometry. Pressure-sensitive transducers are arranged radially along the probe and spaced several centimeters apart. Reusable and disposable probes are available (Isle of Skye, Scotland; Medtronic, Minneapolis, Minnesota; Mui Scientific, Mississauga, Ontario, Canada; Sandhill Scientific, Highlands Ranch, Colorado)
2. A manometric recording device, a computerized recorder and storage device compatible with commercially available software, is recommended. Software programs are designed to perform study interpretation, but editing is required to ensure accuracy
3. A system to display the recording
4. A device to store the data
5. Cotton swab
6. Surgical tape
7. 4-in. × 4-in. gauze or washcloths
9. Water-soluble lubricant
10. Hospital gown
PROCEDURE (HIGH-RESOLUTION AND 3D-HIGH-DEFINITION ANORECTAL MANOMETRY)
Before performing anorectal manometry, the equipment should be assembled and the probe and recorder calibrated according to the manufacturer’s instructions. High-resolution and high-definition anorectal manometry catheters utilize closely spaced circumferentially pressure sensors for better spatiotemporal pressurization of the anorectum. Identify normative values pertaining to the specific anorectal manometry catheter and gender. The International Anorectal Physiology Working Group and the International Working Group for Disorders of Gastrointestinal Motility and Function protocol is listed below (47.1):
1. Lubricate the balloon with a water-soluble lubricant.
2. Position the patient on the left side with knees flexed. Inspect the buttocks, perineum, and the perianal area. Check the sensation of the anterior, posterior, and bilateral positions by rubbing the cotton swab in each location. The presence or absence of anal wink should be documented.
3. The high-resolution catheter is positioned with the posterior demarcation line on the catheter aligned with patient’s dorsal anatomical region. The catheter should be positioned into the rectum approximately 10 cm post the attached balloon indicated by the reference line.
4. Following accurate placement, the patient should receive 3 minutes allowing anal sphincter acclimation.
5. Resting anal sphincter pressure should be assessed for at least 60 seconds.
6. Three short duration squeezes (5 seconds in duration) with 30 seconds recovery period in between each trial. These squeezes assess maximum anal sphincter pressure.
7. A maximum duration squeeze is performed for 30 seconds. This squeeze evaluates the sustainability of the maximum anorectal sphincter pressure.
8. Following a 60 seconds recovery period from the maximum duration squeeze, two cough responses are performed. A 30-second recovery period between each cough. The cough response assesses the spinal reflex pathways by illustrating the external anal sphincter contraction to increased abdominal pressure.
9. Following 30 seconds after the last cough response, instruct the patient to simulate defecation for 15 seconds. Three simulated defecation trials are performed with a 30-second recovery period.
10. The rectoanal inhibitory reflex (RAIR) is assessed by rapidly inflating the balloon with 50 mL of air to assess the relaxation of the internal anal sphincter. If reflex relaxation is not seen, the position of the probe should be confirmed and the rapid inflation repeated.
11. Rectal sensation measurements, first sensation, urgency to defecate, and maximum tolerated, are collected by inflating a nonlatex rectal balloon 10 mL/s. For threshold sensation, the balloon inflation is performed in increments of 10 mL. In relation to urgency to defecate and maximum tolerated, the balloon volume is increased in 30 mL increments. The maximum balloon inflation volume is 250 mL.
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