What Is Anismus?

  • Maya Held Master of Science - MS, Natural Sciences (Organic chemistry/Molecular Biology), UCL, UK
  • Katheeja Imani MRes Biochemistry, University of Nottingham, Malaysia

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If you do not have constipation but it becomes difficult for you to pass stool, it is because your pelvic floor (muscles in the pelvic region of your body that control bowel movements) is impaired or not functioning properly. Anismus has many alternative names, such as pelvic floor hypertonicity, anal sphincter dyssynergia, dyssynergia defecation, and paradoxical puborectalis. The impairment of the pelvic floor muscles leads to troubled defecation.1 Normally, upon defecation, the pelvic floor muscles should relax and this relaxation allows for the evacuation of faeces. In anismus, the puborectalis muscle and anal sphincter contract, which makes defecation difficult.2 The faeces then may become hardened and affect your stomach because they can not be excreted easily.

Anismus can, therefore, lead to chronic constipation due to the hardening of faeces and the inability to pass it out. The diameter of the rectum may enlarge, causing a megarectum. When the muscles causing bowel movements have become impaired, the urge to defecate or to feel defecation is also impaired. Anismus can further cause faecal impaction as hardening and impaction of faeces may irritate the bowel lining, and patients may face chronic trouble and pain during defecation. 

Causes of anismus

Anismus is a functional disorder (a disorder caused by changes or abnormalities in the normal functioning of the body systems). Anismus does not have any origin from an organic disease or neurological condition. The exact cause of anismus still remains unclear, but it is believed it may be caused by stress or straining too hard during defecation.

Signs and symptoms of anismus

Patients suffering from anismus have similar signs and symptoms to chronic or obstructive constipation. These may include:1

  • Increased straining during defecation 
  • Having less than three bowel movements per week
  • Unable to feel your faeces 
  • Loss of sensation during defecation 
  • Hardened and impactful stools 
  • Pain during defecation 
  • Anal and stomach pain 

These symptoms may resemble constipation, but you should thoroughly discuss them with your healthcare provider if you experience any of these symptoms. 

Diagnosis of anismus

Before conducting tests to diagnose anismus, your healthcare provider will conduct tests to rule out other causes of constipation. Once this has been ruled out, your healthcare provider will diagnose anismus via various options. Some of them are 

  • Defecography 
  • Anorectal manometry 
  • Balloon expulsion test 


Your healthcare technician will place a medical paste in your anus to stimulate defecation and check the mechanics of the defecation process using MRI or X-ray.

Anorectal manometry

This test measures the contraction and relaxation of the rectal and anal muscles. Your healthcare technician will insert a small flexible tube with a balloon in one end, which is slowly inflated to mimic the defecation process, and the other end is connected to a machine to monitor the contraction and relaxation. 

Balloon expulsion test

This is done to measure the time taken to defecate. Your healthcare technician will place a vallon in your rectum and inflate it with warm water to stimulate the defection process. 

Management and treatment for anismus

Anismus can be treated and managed by:

  • Biofeedback therapy 
  • Constipation medications 
  • Lifestyle modifications 
  • Dietary fibre supplementations 

Biofeedback therapy

A mind-body physiotherapy technique is used to relieve the patients. Here, patients are guided to get control over their sphincter muscles. The therapist will guide you through various activities. The purpose of these activities is to get control over your muscles. The control helps you to relax and contract your muscles and push effectively during defecation. 

Constipation medications 

Anismus has symptoms resembling constipation, and so many healthcare providers deem it safe to prescribe laxatives or other medications meant to be used for constipation. These anti-constipation or GIT motility-enhancing medications (drugs that increase motility of the gastrointestinal smooth muscle) can facilitate the evacuation of the obstructed stool. 

Lifestyle modifications

Modifying your lifestyle can help in managing and treating paradoxical contractions or anismus. A few of the modifications are:

  • Taking a walk daily 
  • Increased consumption of water can push the hardened stools into the intestine and facilitate defecation 
  • Increased consumption of fibres as they can interact with the obstructed faeces and result in their evacuation 
  • Avoiding medications that can cause constipation
  • Going to the bathroom when you feel the urge to defecate 

Dietary fibre supplementations

Dietary fibre supplementations can also help you in evacuating the obstructed stools. They are also used for constipation and are considered safe to be prescribed to patients with anismus due to the resembling symptoms of constipation. 


How can I prevent anismus?

You can prevent anismus by taking more water. Having more dietary fibres in your diet can also prevent anismus. You are not stopping or delaying defecation. All of these steps can help you prevent anismus. 

Who is at risk of anismus?

People have lost voluntary control over muscles, patients suffering or having extrapyramidal symptoms, or decreased water or fibre consumption. If you consume less water or fibre supplements, there are chances that you may get anismus. Therefore, it is suggested that you maintain your water and fibre intake.

How common is anismus?

Almost 15% to 25% suffering from chronic constipation had anismus

When should I see a doctor?

You should seek medical attention if you face increased pain during defecation or if you see blood in your stool. These are the signs of the extreme condition of anismus. You can also seek medical attention in the early days when there is difficulty evacuating stools. It is preferred to consult your doctor in the initial days when you are confronted with difficulty in defecation because, at this stage, treatment and management can become easier. 


Anismus can be best described as trouble in defecation or difficulty in evacuating faeces. It is caused by the impairment of pelvic floor muscles that control bowel movements. Due to impaired muscles, the faeces are not evacuated and stay in the intestine. The prolonged stay of faeces makes them hardened and impacted, leading to chronic constipation. Failure of the puborectalis and anal sphincter to relax or failure to contract when they should be relaxed is noted. The specific cause of anismus is still unclear, but it is believed it may be caused by stress or straining too hard during defecation. Anismus or dyssynergia defecation has similar symptoms to constipation. The common ones are being unable to defecate, having no sensation while defecating, or hardened or impacted stools. Anismus can be treated with biofeedback therapy, constipation medications, and dietary fibre supplementations, and lifestyle modifications such as increased intake of fibre and water are recommended. 

Therefore, a balanced diet with an appropriate water and fibre intake is recommended to prevent anismus. You should immediately contact your healthcare provider if you have trouble with defecation.  


  1. Hite M, Curran T. Biofeedback for pelvic floor disorders. Clin Colon Rectal Surg [Internet]. 2021 Jan [cited 2024 Jan 22];34(1):56–61. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7843943/
  2. Lee KH, Kim JY. Current situation on the diagnosis of anismus-discordances between imaging and a physiologic study. Ann Coloproctol [Internet]. 2016 Oct [cited 2024 Jan 22];32(5):159. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108660/ 

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Syed Sharf ud Din

Doctor of Pharmacy, University of Central Punjab

Syed Sharf ud Din is a fourth-year pharmacy student. While still in pharmacy school, he has vast interests in biopharmaceutics and pharmacy practise. With an ardent skill of writing combined with background of health sciences, he is curating perfectly designed health-related articles for the general public. He aims to continue his skills and interests in the future to contribute to breakthroughs in pharmaceutical sciences.

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