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What is anismus?
Anismus, also called dyssynergic defecation, is a type of pelvic floor dysfunction that makes it hard to poop. It can lead to chronic constipation. Your “pelvic floor” is a group of muscles in your pelvic area that help control bowel movements, among other things. Pelvic floor dysfunction means these muscles, and the nerves they work with, aren’t coordinating correctly. When poop can’t be released regularly, it becomes hardened and impacted in your bowels, making it harder to pass.
Anismus can take different forms. Most commonly, the muscles that usually hold in your poop fail to relax when you try to have a bowel movement. (This is called hypertonic pelvic floor.) They may even tighten instead. (This is called paradoxical contraction.) Some people are also unable to coordinate their muscles to generate enough force to push poop out effectively. And about half of people with this condition have an impaired ability to feel poop or of the urge to poop.
How common is this condition?
Dyssynergic defecation is estimated to account for 15% to 25% of all chronic constipation cases. Chronic constipation itself is estimated to affect 10% to 20% of people worldwide. It’s about twice as common in people assigned female at birth as in people assigned male at birth. It’s also more common after the age of 65.
Who does dyssynergic defecation affect?
About 1/3 of people with dyssynergic defecation develop it in childhood. Another 1/3 appear to develop it after an event, such as childbirth or injury. The remaining 40% develop it for unknown reasons. It appears to be an acquired behavior, whether conscious or unconscious.
Symptoms and Causes
What causes anismus?
This is a functional disorder, which means the exact cause is unknown. It doesn’t seem 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.
What risk factors might contribute to dyssynergic defecation?
While there is no direct cause, anismus often overlaps with other conditions, including:
- Rectal ulcers.
- IBS-C (Irritable Bowel Syndrome with constipation).
- Slow colonic transit time (passage of food through the body).
- Chronic constipation from childhood.
- Rectal hyposensitivity (lack of sensation in the rectum).
- Psychological disorders.
- Opioid use.
What are the symptoms of anismus?
People with anismus share symptoms of severe constipation. Common symptoms include:
- Less than three bowel movements a week.
- Excessive straining to poop.
- The feeling that you aren’t pooping everything out.
- Hard, painful stools.
- The need to help pull stools out with fingers.
- Bloated stomach.
- Stomach pain.
- Anal pain.
You might feel reluctant to discuss these symptoms, but they are all familiar features of the condition and meaningful to your healthcare provider. Reporting your symptoms honestly will help them diagnose and treat you more effectively.
Diagnosis and Tests
How is dyssynergic defecation diagnosed?
Before diagnosing dyssynergic defecation, your healthcare provider will work to rule out other common structural and metabolic causes of constipation. This may involve several generic rectal exams. They might begin with a digital rectal exam (DRE), a physical examination of your rectum using gloved fingers with lubrication. They might also take a sigmoidoscopy, a look inside with a small lighted scope. If these don’t reveal any obvious causes, they will move on to more specific tests.
What tests will be used to diagnose anismus?
Diagnosis requires a positive result on two or more of the following tests:
An anorectal manometry test will measure the contractions and relaxations of your anal and rectal muscles. It’s done by inserting a small catheter (flexible tube) with a balloon on the end into your anus. A healthcare technician will slowly inflate the balloon, triggering your muscles to respond as they would to poop in your rectum. The other end of the catheter will be connected to a machine that will record your muscle activity. The test can detect:
- Whether or not you can generate adequate pushing force.
- Whether your anal sphincter muscles relax adequately in response to pushing.
- Whether they tighten in response to pushing.
- Whether or not your rectal sensation is in the normal range.
Balloon expulsion test
This test measures how long it takes you to pass stool from your rectum, using a balloon inflated with warm water to simulate a stool. Your healthcare technician will place the balloon in your rectum and inflate it to a fixed level, then give you privacy to expel it in the sitting position. If it takes longer than a minute for you to pass, this suggests pelvic floor dysfunction.
A defocography test uses either X-ray or MRI imaging to watch the internal mechanics of your body in action when you activate them to pass stool. A medical paste simulating poop will be placed in your anus for you to pass in privacy, while X-ray or MRI images are displayed on a screen. The test can help show pelvic floor dysfunction as well as other structural abnormalities that may be contributing.
Sitz marker study
This test uses tiny markers to see how quickly food travels through your intestines. First, your healthcare provider will give you a pill to take. This pill contains tiny markers that will show up on an X-ray. Five days after taking the pill, you’ll have an appointment so your provider can take X-rays. The X-rays will show whether the markers are still in your colon. If the markers are still in your colon, it suggests that waste doesn’t move through your large intestine as quickly as it should.
Management and Treatment
How do you fix anismus?
Biofeedback therapy is the most effective treatment for dyssynergic defecation so far (up to 80%). This is the mainstay, but your healthcare provider may suggest other treatments as a supplement, or if biofeedback doesn't work for you.
This is a mind-body physiotherapy technique that can train you through guided exercises to activate and relax your sphincter muscles at will. Biofeedback uses painless electrodes on your skin to sense things like your heart rate, breathing, skin temperature, muscle tension and brain activity. The results are displayed on a screen for you and your therapist to observe. During a session, your therapist will guide you through various muscle-activating and tension-relieving strategies to see what works. Through practice, you can train your muscles to push effectively and relax effectively enough to poop.
Biofeedback can also help train your sensory awareness. If rectal hyposensitivity is part of your problem, this training can help you notice sooner when you need to move your bowels.
Whether or not you are also using biofeedback therapy, your healthcare provider may recommend some standard lifestyle guidelines to encourage regular bowel movements. These include:
- Avoiding constipating medications.
- Drinking enough water.
- Consuming enough fiber.
- Taking a walk after each meal.
- Going to the bathroom immediately when you have the urge.
- Trying to go to the bathroom at a scheduled time each day.
Your healthcare provider may suggest laxatives or pharmaceuticals for constipation if other methods fail. While these medications haven’t been studied for dyssynergic defecation specifically, they’re effective for chronic constipation in general. Even if they don’t fix your muscle problems, they can help prevent stool from becoming too impacted to pass.
Experimental use of botulism toxin injections for anismus have had mixed results. In theory, Botox can force the necessary muscles to relax, just as it does with wrinkles. It only works about 50% of the time for anismus, though. This may be because anismus is more complex than muscle tension alone. It does seem to work more often with children.
Outlook / Prognosis
What is the outlook for people living with dyssynergic defecation?
If you have access to biofeedback therapy, there’s a good chance this will work for you. However, healthcare providers have noted a general need for greater access. In-home biofeedback devices are in development to help meet this need. You may also find some relief through other available treatments, such as constipation medications and lifestyle changes.
A note from Cleveland Clinic
Healthcare providers always take constipation seriously, especially when it’s chronic or severe. If you have any of the symptoms of anismus, see your healthcare provider right away. It might be an uncomfortable subject to discuss, but not as uncomfortable as the condition.
Speak openly with your provider about your symptoms. Remember, they deal with these subjects every day, and they’ve heard it all. It might be helpful to keep a poop journal prior to your appointment so you can record exactly what happens each day when you try to poop. The more information you can provide, the better-equipped your healthcare provider will be to help you.
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