What is an Anorectal Manometry Test?
An anorectal manometry test is a diagnostic procedure used to evaluate how well the rectum and anal sphincter work to eliminate stool. The end goal of anorectal manometry is treatment customized to address the specific problem. Treatments may include diet, medications, biofeedback, muscle strengthening exercises, or surgery.
It’s a safe, easy, non-invasive test requiring minimal preparation. Because no sedation is needed, there’s no recovery time. Patients can leave the office and return to normal activities immediately after the test.
The procedure uses a catheter with a balloon on the end to evaluate issues like constipation and anal abnormalities. Sensors on the catheter identify and measure pressure and sensation in the anus and rectum, as well as neural reflexes necessary to expel stool.
It can be performed on-site by specially trained nurses.
A comprehensive anorectal manometry procedure may also include:
- Anal sphincter electromyography (EMG) – to confirm appropriate contractions
- Anorectal rest and squeeze pressure profiling – to measure squeeze pressure in 4 quadrants
- Rectal volume measurement – to assess sensation
- Rectoanal inhibitory reflex – to measure response to rectal distention
- Balloon expulsion test – to assess the patient’s ability to expel stool
- Rectal sensory testing: sensation, desire to have a bowel movement, urgency, and pain
What Does an Anorectal Manometry Procedure Assess?
Anorectal manometry is an essential component of a comprehensive assessment of anorectal function. It’s most commonly used for incontinence or constipation but can also provide valuable data related to certain pelvic floor disorders and pre/post-surgical evaluation of anal sphincter tone.
It measures the strength and functioning of the sphincter muscles to determine if they are working correctly when passing stool. Sphincter muscles can be weakened by damage to the muscles or nerves, spinal cord injuries, and complications from surgery.
Sphincter muscles that can’t tighten and relax appropriately may be a contributing factor to difficulties evacuating stool.
With Anorectal Manometry, Treatment Is More Precise
After anorectal manometry, treatment can be customized based on the data collected during the test.
Anorectal manometry procedures are used to diagnose and assess the following disorders:
- Chronic constipation
- Fecal incontinence
- Pelvic floor dyssynergia
- Reduced rectal sensation
- Hirschsprung’s disease
What equipment and supplies are required?
Anorectal manometry testing requires specialized equipment, including:
- Special balloon catheter
- Pressure transducers
- Electrode set
- Blue pads
- Germicidal wipes
- Luer lock syringes
- Lubricating jelly
- A laptop or PC
- Software to collect, record, view, and analyze data
- A printer for printing reports
Equipment can be expensive and may require maintenance or upgrading. It can be purchased or leased. Additionally, staff must be trained to use the equipment and accurately perform testing.
Due to the capital required to buy equipment and train or hire staff, outsourcing to an agency that provides urodynamics services is often a more efficient option. The company BHN provides such Anorectal Manometry testing services.
What Does the Procedure Entail?
During the procedure, the patient lies on their side, like for a colonoscopy. A nurse specially trained in anorectal manometry inserts a small catheter (about the size of a rectal thermometer) into the anal opening, past the anal sphincter and into the rectum.
The balloon on the catheter is slowly inflated, causing the muscles and nerves in the rectum and anus to contract. Sensors in the catheter measure pressure changes, recording the contractions.
The nurse will instruct the patient to squeeze, push, and relax at various times while pressure is recorded.
How Long Does the Procedure Take?
Anorectal manometry testing typically takes 10-45 minutes, which includes:
- Probe placement
- Squeeze tests
- Cough reflex test
- Simulated defecation
- Graded balloon distention
- Recovery periods after insertion of the probe and between tests
Time varies based on the assessments performed.
How are the results interpreted?
The anorectal manometry procedure can assess:
- Anal sphincter function
- Rectoanal reflex
- Rectal sensation
- Changes in pressure during defecation
- Rectal compliance
- Performance on a balloon expulsion test
Pressure readings are transmitted to the manometry software for interpretation, reporting, or exporting data. Interpretation requires training and practice. Like equipment and staff, results analysis can be outsourced for efficiency.
Sensory thresholds may vary based on laboratory, balloon type, and technique and speed of balloon inflation.
Patient Preparation for Anorectal Manometry
Anorectal manometry is very easy on the patient. An empty rectum is necessary for the test, but a complete bowel prep is not. The patient should be NPO after midnight and self-administer a Fleet enema 2-3 hours before the procedure.
Because no sedation is needed, the patient may go home and resume their normal activities and diet immediately after the test.
It is generally not necessary to require the patient to hold most medications before or after the test, with the exception of:
- Smooth muscle relaxants like Valium or Flexeril
- Lovenox injections
- Aspirin, if taken for arthritis or general reasons and not as a blood thinner
- Iron and iron containing multivitamins
- Fiber supplements
- Diabetes medications
After the provider has analyzed the results of the anorectal manometry, treatment options can be discussed with the patient.
Risks of Anorectal Manometry
Pain or complications during anorectal manometry are unlikely, but include:
- Perforation or bleeding of the rectum
- Allergic reaction to latex
- Equipment failure
In most cases, patients may drive immediately after the procedure and return to all normal activities.
Pediatric Anorectal Manometry
Anorectal manometry is also safe and appropriate for pediatric patients. Like in adults, it can help diagnose the cause of constipation, fecal incontinence, and other bowel problems and to assess rectal muscles and nerves before or after surgery. In children, it can also diagnose the absence of nerve cells in the bowel that characterizes Hirschsprung disease.
Children may need to be sedated for the procedure.
The Importance of Precise Diagnosis and Treatment
The symptoms of pelvic floor dysfunction, constipation, and fecal incontinence can severely disrupt your patients’ lives. Patients are often embarrassed by the discomfort and incontinence. Many suffer emotional and social distress and an overall decrease in quality of life. Many patients find it difficult to talk about their symptoms.
Anorectal manometry gives clinicians a more precise method of diagnosing these disorders, giving patients hope for relief.