Anismus (Dyssynergic Defecation): Causes, Symptoms, Diagnosis, and Biofeedback Treatment
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
TL;DR
Anismus, also called dyssynergic defecation, is a functional pelvic floor disorder in which the muscles and nerves that control bowel movements fail to coordinate. Instead of relaxing to let stool pass, the pelvic muscles fail to relax, tighten paradoxically, or cannot generate enough pushing force. It accounts for 15% to 25% of all chronic constipation cases, affects women roughly twice as often as men, and is diagnosed when at least two of four specialized pelvic floor tests come back positive. The most effective treatment is biofeedback therapy, which succeeds in up to 80% of cases by retraining the muscles through guided exercises and real-time visual feedback.
Quick Answer
What is anismus? A functional pooping disorder where pelvic floor muscles and nerves fail to coordinate during a bowel movement, so stool cannot be released normally.
How common is it? Dyssynergic defecation accounts for an estimated 15% to 25% of all chronic constipation cases; chronic constipation itself affects 10% to 20% of people worldwide.
Who gets it? It is about twice as common in women than in men, more common after age 65, and one-third of people develop it in childhood and another third after an event such as childbirth or injury.
How is it treated? Biofeedback therapy is the most effective treatment to date, working for up to 80% of people, supported by lifestyle measures, constipation medications, and in some cases experimental Botox injections.
What Exactly Is Anismus?
Anismus, also called dyssynergic defecation, is a type of pelvic floor dysfunction that makes it hard to poop. Your pelvic floor is a group of muscles in the pelvic area that help control bowel movements, among other things. In anismus, these muscles, and the nerves they work with, are not coordinating correctly.
The condition can cause chronic constipation, and it can also be caused by it. When stool cannot be released regularly, it becomes hardened and impacted in the bowels, making it harder to pass over time. This creates a cycle that often worsens without treatment.
Anismus is a functional disorder: the muscles and nerves are structurally normal, but they fail to work together the way they should.
How Is Anismus Different From Regular Constipation?
Constipation simply describes slow or difficult bowel movements. Anismus is one specific reason constipation happens: the coordination problem itself. Roughly 15% to 25% of all chronic constipation cases trace back to dyssynergic defecation, which makes it one of the most common hidden causes behind persistent constipation that does not respond to fiber or laxatives.
This distinction matters because the treatment is different. Standard constipation remedies address stool consistency, while anismus requires retraining the muscles themselves.
Primary problem: in typical chronic constipation, stool moves slowly or is hard; in anismus, pelvic muscles and nerves fail to coordinate.
Underlying cause: typical constipation is often diet, medications, or transit time; anismus is a learned muscle behavior that is functional, not structural.
Standard treatment: typical constipation responds to fiber, water, and laxatives; anismus is treated with biofeedback therapy (up to 80% effective).
Responds to laxatives alone? Typical constipation usually does; anismus often only partially, because the muscles still need retraining.
What Goes Wrong in the Pelvic Floor?
In a normal bowel movement, the brain signals the pelvic floor muscles to relax while abdominal muscles push. In anismus, that coordination breaks down in several distinct ways.
Most commonly, the muscles that normally hold stool in fail to relax when you try to have a bowel movement. This is called a hypertonic pelvic floor: the muscles stay tense when they should let go. Sometimes the muscles go a step further and actively tighten in response to pushing, a pattern called paradoxical contraction. Pushing against a tightening muscle makes emptying nearly impossible.
A third pattern is simply weak effort: some people cannot coordinate their muscles to generate enough pushing force to move stool out effectively. Finally, about half of people with anismus also have an impaired ability to feel stool or the urge to poop, a related sensory problem called rectal hyposensitivity.
Hypertonic pelvic floor (most common): muscles fail to relax when pushing, so stool cannot pass.
Paradoxical contraction: muscles tighten instead of relaxing, so pushing makes things worse.
Insufficient pushing force: muscles cannot coordinate strong effort, so stool is not expelled effectively.
Rectal hyposensitivity (about half of patients): reduced ability to feel stool or the urge, leading to delayed bathroom trips and harder stool.
How Common Is Anismus, and Who Does It Affect?
Dyssynergic defecation accounts for an estimated 15% to 25% of all chronic constipation cases. Chronic constipation itself is estimated to affect 10% to 20% of people worldwide.
The condition follows several clear demographic patterns. It is about twice as common in women than in men, and it is more common after the age of 65.
Share of chronic constipation cases: 15%–25%
Chronic constipation worldwide: 10%–20% of people
Women vs. men: about twice as common in women
Age pattern: more common after age 65
Develops in childhood: about 1 in 3 cases
Develops after an event (for example, childbirth or injury): about 1 in 3 cases
Develops for unknown reasons: the remaining 40%
Experts note that anismus appears to be an acquired behavior, whether conscious or unconscious, rather than a disease you are born with.
What Causes Anismus?
Because anismus is a functional disorder, the exact cause is unknown. It does not appear to come from any organic disease or neurological condition.
The leading theory is that it may be a learned adaptation to stress or trauma, perhaps even an adaptation to the stress of preexisting chronic constipation and straining too hard. Years of straining can teach the pelvic muscles the wrong habits, and those habits persist even after the original problem changes.
What Risk Factors and Overlapping Conditions Are Associated With It?
While no direct cause exists, anismus frequently overlaps with other conditions. The presence of these conditions raises the likelihood that a constipation problem involves pelvic floor coordination, not just diet or transit time.
Irritable bowel syndrome with constipation (IBS-C): constipation-predominant IBS frequently co-occurs.
Rectal ulcers: associated with chronic straining.
Slow colonic transit time: slower passage through the body.
Chronic constipation from childhood: an early-onset pattern.
Rectal hyposensitivity: reduced sensation in the rectum.
Psychological disorders: stress and mental health overlap.
Opioid use: opioids slow the bowel and worsen constipation.
What Are the Symptoms of Anismus?
People with anismus share the symptoms of severe constipation. Because these symptoms are common and often embarrassing, many people delay seeking care, but they are all familiar features of the condition and meaningful to healthcare providers.
Fewer than 3 bowel movements per week: a hallmark of constipation severity.
Excessive straining: pushing hard with little result.
Feeling of incomplete emptying: not pooping everything out.
Hard, painful stools: the result of stool sitting too long.
Manual stool removal: the need to help pull stools out with fingers.
Bloated stomach: distension from retained stool.
Stomach pain: abdominal discomfort.
Anal pain: pain in the anal area.
Reporting your symptoms honestly, including sensitive ones like manual removal, helps providers diagnose and treat the condition more effectively. Providers deal with these subjects every day.
How Is Anismus Diagnosed?
Diagnosis is a two-stage process. First, the provider works to rule out other common structural and metabolic causes of constipation. Then, if nothing structural explains the problem, specialized pelvic floor tests confirm the coordination disorder.
Stage 1: Ruling Out Structural Causes
The process usually begins with a digital rectal exam (DRE), a physical examination of the rectum using gloved, lubricated fingers. The provider may also perform a sigmoidoscopy, using a small lighted scope to look inside.
Stage 2: Specialized Pelvic Floor Testing
A dyssynergic defecation diagnosis requires a positive result on two or more of the following four tests:
Anorectal manometry: a small catheter with a balloon on the end is inserted; the balloon is slowly inflated and a machine records muscle activity. It shows whether you can generate adequate pushing force and whether the anal sphincter relaxes, tightens, or fails to respond.
Balloon expulsion test: a balloon inflated with warm water simulates stool, and you expel it in private while sitting. Taking longer than 1 minute suggests pelvic floor dysfunction.
Defecography: X-ray or MRI imaging watches the internal mechanics while you pass a medical paste simulating stool. It detects pelvic floor dysfunction plus structural abnormalities.
Sitz marker study: a pill containing tiny X-ray-visible markers is swallowed, and X-rays on day 5 check the colon. Markers that remain indicate slow transit.
The manometry test is particularly informative: it shows not just whether you can push, but exactly how your sphincter muscles respond: relaxing, staying tense, or actively tightening in response to pushing.
How Do You Fix Anismus?
Biofeedback therapy is the most effective treatment for dyssynergic defecation to date, working for up to 80% of patients. It is the mainstay of treatment, with other options used as supplements or when biofeedback is unavailable or unsuccessful.
Biofeedback Therapy (Up to 80% Effective)
Biofeedback is a mind-body physiotherapy technique that trains you, through guided exercises, to activate and relax your sphincter muscles at will. Painless electrodes on the skin sense your heart rate, breathing, skin temperature, muscle tension, and brain activity, and display the results on a screen for you and your therapist to observe.
During sessions, the therapist guides you through muscle-activating and tension-relieving strategies to find what works. With practice, you can train your muscles to push effectively and relax effectively enough to poop.
Biofeedback also trains sensory awareness: if rectal hyposensitivity is part of your problem, the training can help you notice sooner when you need to move your bowels.
Skin electrodes and on-screen display: make invisible muscle activity visible in real time.
Guided push/relax exercises: retrain correct coordination patterns.
Sensory awareness training: improves detection of the urge to go.
Reported success rate: up to 80% of patients.
Lifestyle Remedies
Whether or not you also use biofeedback, providers typically recommend standard lifestyle guidelines to encourage regular bowel movements:
Avoid constipating medications, which removes a common aggravating factor.
Drink enough water to keep stool softer and easier to pass.
Consume enough fiber to add bulk and regularity.
Walk after each meal to stimulate bowel motility.
Go immediately when the urge arrives, to prevent stool hardening.
Schedule daily bathroom time to build a consistent rhythm.
Constipation Medications
If other methods fall short, providers may suggest laxatives or pharmaceuticals for constipation. These medications have not been studied specifically for dyssynergic defecation, but they are effective for chronic constipation in general. Even if they do not fix the underlying muscle problem, they help prevent stool from becoming too impacted to pass.
Botox Injections (Experimental)
Experimental use of botulinum toxin (Botox) injections for anismus has had mixed results. In theory, Botox can force the necessary muscles to relax. In practice, it works only about 50% of the time for anismus, possibly because the condition is more complex than muscle tension alone. It does appear to work more often in children.
Biofeedback therapy: the most effective treatment to date; up to 80% success.
Lifestyle remedies: standard supporting measures; results vary.
Constipation medications: not studied for anismus specifically; they help prevent impaction.
Botox injections: experimental; about 50% success.
What Is the Outlook for People With Anismus?
If you have access to biofeedback therapy, there is a good chance it will work for you. Healthcare providers have noted a general need for greater access to biofeedback; in-home biofeedback devices are currently in development to help meet that need. Even without biofeedback, relief is possible through constipation medications and lifestyle changes.
The key message: this condition is treatable, and waiting rarely helps. The longer stool remains impacted, the harder the problem becomes.
When Should You See a Healthcare Provider?
Healthcare providers always take constipation seriously, especially when it is chronic or severe. If you have any of the symptoms of anismus, particularly straining, incomplete emptying, or fewer than three bowel movements a week, see your healthcare provider right away.
It might be an uncomfortable subject to discuss, but it is not as uncomfortable as the condition itself. Providers deal with these subjects every day and have heard it all.
One practical tip from providers: keep a poop journal in the days before your appointment, recording exactly what happens each day when you try to poop. The more information you provide, the better-equipped your provider is to help.
Conclusion: Chronic Constipation Deserves a Proper Diagnosis
Anismus proves that not all constipation is the same. When the problem lives in the muscles and nerves of the pelvic floor rather than in the stool itself, fiber and laxatives can only do so much. Recognizing the signature pattern, excessive straining, incomplete emptying, and sometimes even manual removal, is the first step toward real relief.
If your constipation has persisted despite standard measures, ask your provider specifically about dyssynergic defecation and whether pelvic floor testing is appropriate. With biofeedback therapy working for up to 80% of patients, the single most important action is getting evaluated rather than continuing to suffer in silence.
Take action today: If you have fewer than three bowel movements a week, strain excessively, or feel you cannot empty completely, book an appointment with your healthcare provider, and consider asking whether anorectal manometry or a balloon expulsion test could reveal a coordination problem hiding behind your constipation.
Frequently Asked Questions
What is the difference between anismus and regular constipation?
Regular constipation describes slow or difficult bowel movements, while anismus (dyssynergic defecation) is a specific functional cause: the pelvic floor muscles and nerves fail to coordinate during a bowel movement. Dyssynergic defecation accounts for an estimated 15% to 25% of all chronic constipation cases.
What causes dyssynergic defecation?
The exact cause is unknown. It is a functional disorder that does not appear to come from any organic disease or neurological condition. It may be a learned adaptation to stress or trauma, perhaps even to the stress of preexisting chronic constipation and straining too hard.
Is anismus more common in women or men?
Anismus is about twice as common in women than in men, and it is more common after the age of 65. About one-third of people develop it in childhood, another third after an event such as childbirth or injury, and the remaining 40% develop it for unknown reasons.
What are the signs that my constipation might be anismus?
The key symptoms include fewer than three bowel movements a week, excessive straining, a feeling of incomplete emptying, hard and painful stools, needing to help pull stool out with fingers, bloating, stomach pain, and anal pain. Needing manual removal is a particularly strong clue that a coordination problem may be involved.
How is anismus diagnosed?
After ruling out structural and metabolic causes with a digital rectal exam and sigmoidoscopy, diagnosis requires a positive result on two or more of four specialized tests: anorectal manometry, the balloon expulsion test, defecography, and the sitz marker study.
What is biofeedback for anismus and does it work?
Biofeedback is a mind-body physiotherapy that uses painless skin electrodes and an on-screen display to help you retrain your pelvic floor muscles to push and relax correctly. It is the most effective treatment for dyssynergic defecation, working for up to 80% of patients.
Can laxatives cure anismus?
Laxatives and constipation medications have not been studied specifically for dyssynergic defecation, but they are effective for chronic constipation in general. They can prevent stool from becoming too impacted to pass, even though they do not fix the underlying muscle coordination problem.
Does anismus go away on its own?
Not typically without treatment, since the underlying cause is a learned muscle pattern. However, the outlook is good with treatment: biofeedback therapy succeeds in up to 80% of cases, and lifestyle measures plus constipation medications provide additional relief.
References
International Foundation for Gastrointestinal Disorders. "Dyssynergic Defecation: About a Common Cause of Chronic Constipation." Accessed 5/24/2022. https://iffgd.org/gi-disorders/dyssynergic-defecation/
Rao SS, Patcharatrakul T. "Diagnosis and Treatment of Dyssynergic Defecation." J Neurogastroenterol Motil. 2016;22(3):423-435. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4930297/
Rao SS, Jehangir A. "Dyssynergic defecation." GI & Hepatology News. April 23, 2021. https://www.mdedge.com/gihepnews/article/239125/ibd-intestinal-disorders/dyssynergic-defecation
Medical Disclaimer: This article is for general educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and treatment of any medical condition. If you experience severe or worsening symptoms, seek professional medical care promptly.
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