Having a bowel movement once a week, spending long minutes in the toilet… For many, constipation is experienced as an inevitability linked to diet or lack of hydration. Yet for many patients, the problem is not what they eat, but how their body evacuates.
There is thus a still largely unknown cause of chronic constipation: pelvic floor dysfunction, also called anorectal dyssynergia. A common condition, but rarely identified, which explains why some constipation resists fiber, laxatives and good habits.
When do we really talk about constipation?
Constipation is not just a matter of rhythm. From a medical point of view, it is defined by fewer than three bowel movements per week, but it is mainly manifested by difficulty in evacuating. Hard or fragmented stools, heavy straining, pain during defecation, bloating or the feeling of never having completely emptied your intestines are some of the most common signs.
In the majority of cases, a diet low in fiber, insufficient hydration, a sedentary lifestyle, stress or certain medications are to blame. But when these factors have been corrected without significant improvement, another hypothesis must be considered.
What if the intestine works…but the exit doesn’t?
“We tend to think that constipation comes from a slow intestine. However, this is not always true”explains Dr. Gérald Kierzek. In some cases, the transit brings the stools correctly to the rectum, but their evacuation is blocked by a muscular problem.
It is then a disorder of coordination of the muscles of the anorectal region, which doctors call anorectal dyssynergia, dyschezia or anismus. In other words, the right signal is not given at the right time.
A defecation mechanism that goes wrong
A little anatomical review. Normally, having a bowel movement is based on a succession of perfectly coordinated movements. The abdominal thrust increases pressure, the rectum contracts, while the external anal sphincter and puborectalis muscle relax to open the anorectal angle and allow passage of stool.
In dyssynergia, this mechanism seizes up. “Muscles that should relax contract when pushing, or relax incompletely“, explains Dr. Kierzek. Result: the anorectal angle remains closed, the stools are blocked, and the person may push, nothing comes out.
This situation creates a very characteristic feeling of obstruction, sometimes even when the stools are not particularly hard. The more they stagnate, the more the water they contain is reabsorbed by the body, which further aggravates constipation and increases pressure on the pelvic floor. A real vicious circle sets in.
How to make the diagnosis?
How do you know if this concerns you? The diagnosis begins with a precise questioning. Excessive straining during bowel movements, the feeling of rectal blockage or the need for manual aids quickly directs the doctor.
To confirm, specialized examinations can be carried out in digestive functional exploration centers. Anorectal manometry is the key examination: it allows pressure to be measured and the behavior of the muscles to be visualized during pushing.
“We highlight an absence of relaxation, or even a paradoxical contraction of the anal sphincter at the moment when it should open”explains Dr. Kierzek. Other tests, such as the expulsion test or defecography, can complete the assessment.
Why laxatives are not enough
Faced with chronic constipation, many patients continue to take laxatives, sometimes for years. While they may improve the consistency or frequency of stools, they do not correct the underlying problem.
“In true defecation dyssynergia, laxatives alone are insufficient, because they do not re-educate muscular coordination” recalls Dr. Kierzek. In short, they can help occasionally, but do not allow lasting improvement.
Don’t get stuck, treatment is possible!
The management of defecation dyssynergia relies above all on simple but essential basic measures. This involves adapting the fiber diet, neither too low nor excessive or too fermentable, maintaining sufficient hydration, and adopting an easier position during defecation (feet raised, trunk slightly leaning forward). It is also important to respect the gastrocolic reflex after meals, which naturally promotes defecation.
The treatment of choice remains perineal rehabilitation with biofeedback. This approach allows the patient to learn to voluntarily relax the sphincter and to coordinate abdominal thrust and opening of the pelvic floor. Using sensors or a rectal probe, pressures can be viewed in real time, making learning easier.
“Randomized trials have shown that a few biofeedback sessions are significantly more effective than laxatives, such as polyethylene glycol, in improving bowel movement frequency, reducing the sensation of obstruction and normalizing anal relaxation, with lasting benefit for one to two years” assures the doctor.
A common cause, still too little known
It is estimated that approximately one in two people with chronic constipation have pelvic floor dysfunction. However, this diagnosis remains rarely mentioned, leaving many patients in medical wandering.
If your constipation persists despite a balanced diet, good hydration and physical activity, the problem may not come from your intestine, but from your muscles. And good news: once identified, this cause can be treated effectively!