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Understanding Dyssynergic Defecation | Health Plus

Understanding Dyssynergic Defecation | Health Plus

If you have infrequent bowel movements, or find it difficult to pass stool, it could be a sign of dyssynergic defecation. What is this condition, and how is it different from slow transit constipation?

What is dyssynergic defecation (DD)?

DD is a condition where a person overstrains to start a bowel movement and has great difficulty completing it. Many people with DD do not realise they have a problem until they are present with complications from years of overstraining. These people overstrain because they are unable to coordinate the muscles that help a bowel movement. This disordered muscle contraction and relaxation leads to inability to pass normal stools through the anus. The pelvic floor and anal muscles are structurally normal in people with DD.

DD is also known by many other names: anismus, obstructed defecation, pelvic floor dyssynergia and puborectalis paradoxus syndrome. Most of these terms are interchangeable. Some of the more common presentations of people with untreated DD are recurrent anal fissures, rectocoele and rectal prolapse.

If you suspect you may have DD, consult a specialist for a diagnosis.

How does it differ from slow transit constipation (STC)?

Patients with STC tend to have less than 1 bowel movement every 3 days, while patients with DD usually have regular bowel movement but have difficulty completing it. Often, patients with STC and DD have similar symptoms, such as abdominal cramps and bloating, but treatments can be quite different for both.

What are some causes of DD?

Dyssynergic defaecation causes
The causes are unknown but believed to be due to the random nature of learning how to have a bowel movement. Each toddler learns their own pattern of bowel movement when asked to sit on a ‘potty’. This pattern stays with them for life unless they can relearn a better pattern.

For a normal person, the initiation of a bowel movement is a sensation of fullness in the rectum. This is followed by transient relaxation of the anal sphincter muscles to allow specialised nerves in the anus to determine the nature of the content – whether it is solid, liquid or gas. The message is sent to the brain and the person then decides whether it is a suitable time for a bowel movement and looks for a toilet.

In the toilet, the person then chooses their favourite position (squatting or sitting) and a complex coordination of contraction of abdominal and pelvic muscles (to push content out of the rectum) coupled with relaxation of the anal sphincter muscles (to open the anus and allow content out) permits the act of a bowel movement. This sequence is then repeated several times until the bowel movement is completed.

In patients with DD, there can be an abnormality at any phase of the bowel movement, from sensing the fullness in the rectum to opening the anal orifice. When there is difficulty evacuating faeces from the rectum, the patient will then increase abdominal straining to force the faeces out. This occasionally happens secondary to physical or neurological conditions, such as patients with osteoarthritis of the hips and knees, or patients with Parkinson’s disease.

Who is prone to it?

It has been suggested that up to 20% of people without bowel problems have some degree of DD. Not all will develop problems but DD is commonly seen in patients with haemorrhoids, anal fissures, rectocoeles and rectal prolapse. People who have to strain very hard to have a bowel movement may be suffering from DD.

What are the symptoms of DD?

Dyssynergic defaecation symptoms
Many patients have symptoms of abdominal bloating and cramps that are relieved by bowel movement. However, the patient will usually have to sit or squat at the toilet for a very long time (up to 30 minutes in some cases) and need to strain very hard before the stools can come out. Some say they strain until they break out in sweat. Once the stool starts coming through the anus, there is usually less difficulty completing the bowel movement.

Due to repeated straining, many complain of heaviness or pain around the anus after the bowel movement. Some feel a sense of incomplete emptying of the rectum even after straining for half an hour. Others feel a cramping pain deep in the pelvis, most likely from rectal wall spasm, due to the repeated abdominal straining.

As DD and STC are not mutually exclusive, some patients with DD also have infrequent bowel movements and other constipation symptoms.

What are some treatments available?

The mainstay of treatment of DD is anorectal biofeedback (pelvic floor rehabilitation physiotherapy with dietary and lifestyle modifications) with or without medication. Anorectal biofeedback aims to correct the problem of muscle coordination of the pelvic muscles as well as coping mechanisms for these patients with DD. Surgery is reserved for patients who have developed structural abnormalities as a complication of long-standing DD such as rectocoele and rectal prolapse.

What is the success rate for this treatment?

Anorectal biofeedback has been shown to improve various aspects of the patient's quality of life, with sustained improvement in 71% of patients even after 1 year of treatment. The treatment is non-invasive, has no complications and can be repeated.

Speak to a specialist if you are seeking treatment for dyssynergic defecation or other gastrointestinal disorders.


Article contributed by Dr Lim Jit Fong, general surgeon at Gleneagles Hospital

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