Although most people consider the act of defecation (i.e. bowel movement) a near automatic function, it is actually a complex process that requires the coordination of multiple neuronal and muscular interactions. The pelvic floor consists of a sheet of muscles that not only support the pelvic organs, but also allow for defecation.
What causes obstructed defecation?
When a person decides to pass stool, a complex and coordinated series of abdominal and pelvic muscular relaxation and tightening occurs to allow stool to be passed through the anus. If this process is out of synch, then a person’s pelvic floor musculature will be seen to tighten instead of relax at the proper moment – this leads to constipation, straining and incomplete emptying as they are pushing against a closed muscular wall.
What are the symptoms of obstructed defecation?
Symptoms of pelvic floor dysfunction include constipation, inability to pass stools and the sensation of incomplete emptying of the rectum. Patients often strain mightily to pass small, incomplete stools and then find themselves returning to the toilet multiple times in order to eventually evacuate the remaining stool. As the condition worsens, residual stool in the rectum may leak out through the anus accidently, resulting in fecal incontinence.
How is obstructed defecation diagnosed?
The diagnosis of a pelvic floor disorder starts with a careful history regarding an individual’s symptoms, medical problems and a history of physical or emotional abuse that may be contributing to their problem. Patients have often suffered with this problem for many years and often have developed ways to assist the act of defecation, such as using multiple laxatives and manually assisting themselves to defecate.
All patients suffering from severe constipation that fails to improve with medical treatment should undergo a comprehensive workup to diagnose the cause of the problem. The first step is to ensure that the constipation is not being caused by a mechanical blockage of the colon or rectum, such as from a growing tumor. This is done by performing a colonoscopy or barium enema (an x-ray study taken after instilling the colon with a contrast material). Once a mechanical problem is ruled out, the function of the colon and rectum should be assessed. This is done by assessing the function of both the colon in moving waste towards the rectum and the body’s ability to properly evacuate this waste.
- The colonic transit, or Sitzmark Study, is performed over the course of several days. On the first day, the patient ingests a capsule which contains multiple markers. An x-ray of the abdomen is then taken five days later and the number and pattern of markers remaining in the colon allows us to determine if the colon is functioning properly.
- Next, a defecography study or dynamic pelvic-floor MRI is used to assess the function of the pelvic musculature. Both of these studies will be able to determine if the pelvic floor muscles are not relaxing in a synchronized fashion during the act of defecation, they can also diagnose other causes of obstructed defecation, such as rectocele, enterocele or rectal prolapse.
How is obstructed defecation treated?
An attempt at medical and dietary management of chronic constipation often meets with good results. Those patients who continue to have difficulty and are found to have rectal prolapse, rectocele, enterocele or delayed colonic transit can be helped with surgical intervention. For people with pelvic floor dysfunction (a.k.a. dyskinetic puborectalis, paradoxical puborectalis, non-relaxing puborectalis or anismus) surgical intervention is not an option. The greatest chance of successfully managing pelvic floor dysfunction is through a structured program of pelvic floor re-training. This is done by working closely with a specialized therapist and completing a ‘biofeedback” program for pelvic retraining. This retraining has been seen to improve symptoms in up to 70% of people with pelvic floor dysfunction.