Understanding Your Anorectal Manometry Results
Your anorectal manometry test measures the pressures and coordination of your anal sphincter muscles and rectum to identify specific problems causing your bowel symptoms—the results will show whether you have weak sphincter muscles (causing fecal incontinence), poor muscle coordination during defecation (dyssynergic defecation), or abnormal rectal sensation. 1
What the Test Actually Measures
Anorectal manometry evaluates several key functional parameters:
Anal Sphincter Pressures:
- Resting pressure: Measures the baseline tone of your internal anal sphincter (the muscle that stays contracted automatically to maintain continence)
- Squeeze pressure: Measures how strongly you can voluntarily contract your external anal sphincter
- These values decline with age in both men and women, and squeeze pressure is typically higher in men than women 2, 3
Defecation Coordination:
- Push maneuver: Shows whether your pelvic floor muscles properly relax when you attempt to defecate
- Dyssynergic defecation is diagnosed when you paradoxically contract (rather than relax) your anal sphincter or fail to generate adequate rectal push pressure during simulated defecation 1
Rectal Sensation:
- First sensation: The smallest balloon volume you can feel in your rectum
- Urge to defecate: The volume that triggers the desire to have a bowel movement
- Maximum tolerated volume: The largest volume you can comfortably hold
- Abnormally high thresholds indicate rectal hyposensitivity; abnormally low thresholds indicate hypersensitivity 1, 4
Rectoanal Reflexes:
- The rectoanal inhibitory reflex (RAIR) tests whether your internal sphincter automatically relaxes when the rectum fills—absence suggests Hirschsprung disease 4
Key Abnormalities and What They Mean
Dyssynergic Defecation (Pelvic Floor Dysfunction): This is the most common finding in patients with chronic constipation and difficult evacuation. The test identifies this when you show inadequate anal relaxation or paradoxical anal contraction during attempted defecation, often combined with inadequate rectal push effort. If your results show dyssynergic defecation confirmed by an abnormal balloon expulsion test (taking >60 seconds to expel a balloon), you are an excellent candidate for biofeedback therapy, which successfully treats 70-80% of patients 1.
Anal Sphincter Weakness: Low resting or squeeze pressures indicate weak sphincter muscles, which can cause fecal incontinence. This may result from aging, childbirth trauma, or nerve damage. Biofeedback therapy can help strengthen these muscles and improve sensory perception in 76% of patients with refractory fecal incontinence 1.
Rectal Sensory Dysfunction:
- Hyposensitivity (high thresholds): You require larger volumes to feel rectal filling, which can contribute to both constipation and fecal incontinence
- Hypersensitivity (low thresholds): You feel rectal filling at abnormally small volumes, causing urgency and frequent bowel movements
- Both can be treated with specialized biofeedback sensory training 1
Important Interpretation Caveats
Age and sex matter significantly: Your results must be compared to age- and sex-matched normal values. Resting pressure decreases with age in both sexes, squeeze pressure is lower in women, and rectal sensitivity decreases with age in women 2, 3. Unfortunately, standardized normal values across all demographics and equipment types remain incomplete 1.
Discordant results require additional testing: If your manometry shows dyssynergic defecation but you can expel a balloon normally (or vice versa), you may need a third confirmatory test like defecography to clarify whether true pelvic floor dysfunction exists or if structural abnormalities are present 1.
Position matters: Seated manometry is preferred for evaluating defecation disorders because it better simulates the natural defecation position, though not all centers perform testing this way 1.
What Happens Next
If dyssynergic defecation is confirmed: You should be referred for biofeedback therapy, which uses visual or auditory feedback to retrain your pelvic floor muscles to coordinate properly during defecation. This is a Grade A recommendation with 70-80% success rates 1. Predictors of good response include lower baseline constipation scores, shorter colonic transit times, and use of digital maneuvers to assist defecation 1.
If anal sphincter weakness is found: Biofeedback can strengthen sphincter tone and enhance rectal sensory perception, improving fecal incontinence symptoms in the majority of patients 1.
If sensory abnormalities are identified: Specialized sensory retraining protocols using balloon distension can normalize rectal sensation thresholds 1.
Common Pitfalls to Avoid
The test results should not be interpreted in isolation—they must correlate with your specific symptoms. Some manometric findings (like dyssynergic patterns) can occur in up to 15% of asymptomatic healthy people 2, 5, so clinical context is essential. Additionally, the presence of conditions like IBS, depression, or elevated first rectal sensory thresholds may predict poorer response to biofeedback therapy 1.
Request that your physician explain which specific abnormalities were found, how they compare to age- and sex-matched normal values, and whether biofeedback therapy or other targeted treatments are appropriate for your situation.