Bowel Accidents – Causes of Accidental Bowel Movements

Having an accident with bowel movements is not only embarrassing and inconvenient but it is also an indication that there is an underlying medical problem. Most children are toilet trained by the age of 4 years and bowel accidents are rare later in childhood, except when it occurs with diarrheal illnesses like gastroenteritis. For adults, it should not occur but 18 million Americans have bowel control problems for various reasons.

What is a bowel accident?

A bowel accident is just a simple way of describing a medical condition known as fecal incontinence or bowel incontinece. It refers to a bowel movement that occurs unintentionally and without being able to restrain it for long enough to find a suitable setting to defecate. Simply, it means that a person soils themselves with stool. Sometimes there is a small amount of stool passed out while at other times it is a complete bowel emptying.

Although a bowel accident may occur with severe diarrhea where there is inability to restrain the stool, it can also occur with constipation. Bowel accidents are therefore not only due to diarrhea. In chronic cases it is due to a problem with the nerves and/or muscles that affect bowel control. Apart from very young children, bowel accidents are more likely to affect older adults, especially the elderly with underlying medical problems.

Read more on fecal incontinence.

Why do bowel accidents occur?

Bowel control is a complex interplay of different processes. When the lower bowels become filled with stool, it pushes the stool into the rectum. As a result the rectal walls stretch. Tiny stretch receptors in the walls of the rectum sends signals to the spinal cord. This is the reason we feel the urge to pass stool. As it stretches further, the urge becomes stronger and compels us to find a suitable setting to pass stool.

In addition, the nerve signals cause the external anal sphincter to relax in preparation for a bowel movement. This sphincter is not under voluntary control. However, the internal anal sphincter is under voluntary control and a person can relax it when the setting is suitable to have a bowel movement. There are strong colon and rectal contractions and then the stool is passed out into the environment.

With bowel accidents, some of these mechanisms fail to prevent stool from passing out in a controlled manner. It often arises with weakness of the muscular anal sphincters or disrupted nerve signals to keep these sphincters closed. However, there are other mechanisms that may also play a role in passing out of stool without any control depending on the underlying cause.

Causes of Bowel Accidents

There are a number of medical conditions that can affect bowel control which has been discussed below. Inactivity or purposely avoiding to pass stool can also contribute to fecal incontinence which may lead to bowel accidents. The elderly and frail with limited mobility may not be able to access a toilet frequently enought. People suffering with dementia may no longer have the proper social habits to restrain themselves and can therefore soil the clothing.

Diarrhea and Constipation

Bother alterations of bowel habit, diarrhea or constipation, can lead to bowel accidents at any age.

Diarrhea is a condition that affects every person several times in their life. Most of the time it is due to food poisoning or gastroenteritis which causes acute diarrhea. When the infection is severe, a person may not be able to reach a toilet in time and then soil themselves. These types of bowel accidents may occur occasionally and stop once the diarrhea resolves.

On the other end, bowel accidents can also occur with constipation. In chronic constipation, particularly severe cases, fecal impaction can occur. This is where the stool becomes backed up and forms a hard plug that prevents the outflow of stool. However, fluid stool can pass around this obstruction and the leak out of the anus. Very hard and large stool that may be passed out with constipation can also injure the anorectal region and lead to bowel accidents in the future.

Muscle Weakness

Apart from the muscles in the colon and rectum walls, the pelvic floor muscles also play a role in defecation. These muscles relax to allow the rectum to straighten and for stool to transit out of the bowels with ease. Damage to or weakening any of these muscles can affect bowel movements in various ways and contribute to episodes of bowel accidents. This may occur with:

  • Childbirth, particularly where there has been injury with vaginal delivery.
  • Surgery to the pelvis and/or perineum, such as hemorrhoid surgery.
  • Other forms of trauma to the pelvis and/or perineum.

Read more on weak bowel muscles.

Nerve Problems

Nerves are the conduits for signals to control the expulsion of stool. These nerves can become damaged or diseased in various ways. In some cases it may even be severed.  These types of problems may occur with:

  • Stroke
  • Spinal cord injury
  • Diabetic neuropathy (nerve damage due to long term diabetes)
  • Multiple sclerosis
  • Head trauma

Two common contributing factors to nerve problems that can lead to bowel accidents are childbirth and chronic constipation. As with muscle weakness, nerve problems may arise from childbirth if there is forceps delivery or an episiotomy had to be done. In terms of constipation, the repeated straining to pass out stool can damage nerves.

Stiff Rectum

The ability of the rectum to stretch serves various important functions, such as holding stool and facilitating bowel movements. Stiffness of the rectum is more likely to occur when the walls of the rectum become scarred. This can occur with injury such as radiation exposure (for cancer treatment) or inflammatory conditions like inflammatory bowel disease (IBD). Stool may leak out as the rectum fills since the walls cannot stretch as normal.

Other Causes

Anal and/or rectal conditions can also result in fecal incontinence. This may be seen with:

  • Hemorrhoids where the rectal veins become inflamed and enlarged.
  • Rectal prolapse where a portion of the rectum collapses and impairs proper closure of the anal sphincter.
  • Rectocele where there is a communication channel between the rectum and vagina in women.

Although bowel accidents are uncommon in irritable bowel syndrome (IBS) this condition has to be considered when a person has severe diarrhea during flareups.

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