Bowel Dysfunction

How normal bowel control works

Stool moves through the colon by waves of muscle contraction. When it reaches the rectum, stretch sensors send a signal to the brain, and you feel the urge to go. The internal anal sphincter stays closed automatically, while the external sphincter and pelvic floor muscles are squeezed voluntarily to hold on until it is convenient. Emptying needs coordinated relaxation of these muscles plus gentle abdominal pressure. Problems with nerves, muscles, sensation, stool consistency or mobility can disrupt this system.

Types and symptoms

• Constipation-type dysfunction: infrequent stools, hard stools, straining, a feeling of incomplete emptying, needing to press around the anus or vagina to pass stool.
• Incontinence-type dysfunction: urgency, leakage of stool or gas, soiling of underwear, inability to make it to the toilet. See fecal incontinence.
• Mixed: constipation with overflow leakage, or alternating patterns.
• Low anterior resection syndrome (LARS): frequency, urgency, clustering of bowel movements and incontinence after rectal cancer surgery.

Causes

Neurogenic bowel

Neurogenic bowel is bowel dysfunction caused by nerve damage:

• Spinal cord injury: injuries above the lower spinal cord (upper motor neuron) cause a reflexive, spastic bowel with constipation and tight sphincter; injuries to the lower cord or cauda equina (lower motor neuron) cause a flaccid bowel with slow transit and a loose sphincter, leading to leakage.
• Multiple sclerosis: constipation and urgency are common.
• Stroke, Parkinson's disease, spina bifida and diabetes (autonomic neuropathy).

Muscle and structural causes

• Childbirth injury: tears of the anal sphincter during vaginal delivery, sometimes unrecognized for years.
• Pelvic floor dysfunction: muscles that tighten instead of relaxing when you push (dyssynergic defecation).
• Rectocele and rectal prolapse.
• Surgery and radiotherapy: hemorrhoid or fistula surgery, rectal cancer surgery, pelvic radiation.

Functional and other causes

• Irritable bowel syndrome: pain with diarrhea, constipation or both.
• Medicines: opioids, anticholinergics, iron and some antidepressants cause constipation; antibiotics, metformin and magnesium can loosen stools.
• Low fiber and fluid intake, inactivity and immobility.
• Dementia and reduced mobility, which make reaching the toilet or recognizing the urge harder.

Diagnosis

1. History and bowel diary: frequency, stool type (Bristol Stool Chart), leakage, urgency, diet, medicines and obstetric history.
2. Examination: abdomen, perianal skin, and a digital rectal exam to check sphincter tone, squeeze and coordination, impaction and prolapse.
3. Tests when needed: - Anorectal manometry: measures sphincter pressures, rectal sensation and coordination. - Balloon expulsion test: checks the ability to push out a small balloon. - Endoanal ultrasound: looks for sphincter tears. - Defecography: X-ray or MRI during emptying for prolapse and rectocele. - Colonoscopy: for bleeding, weight loss, age-appropriate screening or new symptoms after 45. - Blood tests: thyroid, calcium, glucose.

Treatment

Bowel program and lifestyle

• Regular timing: try to empty the bowel at the same time daily, ideally 20 to 30 minutes after a meal to use the gastrocolic reflex.
• Toilet position: feet on a small stool so knees are above hips, leaning forward.
• Fiber and fluids: gradually build to 25 to 30 g of fiber a day; psyllium can firm loose stools and soften hard ones.
• Activity: regular movement helps bowel transit.

Medicines

• For constipation: osmotic laxatives (polyethylene glycol), stimulants (senna, bisacodyl), suppositories and enemas.
• For loose stool and leakage: loperamide to slow the bowel and firm stools, following the label dose; bile acid binders for bile acid diarrhea.
• For neurogenic bowel: a planned routine with suppositories or digital stimulation, as taught by a nurse.

Pelvic floor therapy and biofeedback

A specialist physical therapist teaches pelvic floor strengthening for leakage, and relaxation and coordination for dyssynergic constipation. Biofeedback uses sensors to show muscle activity and is highly effective for dyssynergia.

Transanal irrigation

Water is introduced through the anus with a small device to empty the lower bowel on a schedule. It helps many people with neurogenic bowel and LARS.

Procedures and surgery

• sacral nerve stimulation for fecal incontinence
• sphincter repair for childbirth tears
• surgery for rectal prolapse or large rectocele
• an antegrade continence enema (ACE) or a stoma when other treatments fail; a stoma can greatly improve quality of life for some people

Living with bowel dysfunction

Keep a bowel routine, carry a small kit with wipes and spare underwear, use skin barrier creams to protect against irritation, and plan toilet access when out. Many people find bowel symptoms embarrassing to raise, but they are common and treatable. Continence nurses and colorectal specialists can help.

Frequently asked questions

What is bowel dysfunction?

Bowel dysfunction is any long-term problem with storing or emptying stool, including chronic constipation, incomplete emptying, urgency and leakage. It can be caused by nerve damage, pelvic floor problems, childbirth injury, surgery, IBS or medicines.

What is neurogenic bowel dysfunction?

Neurogenic bowel dysfunction is loss of normal bowel control due to nerve damage, most often from spinal cord injury, multiple sclerosis, spina bifida or stroke. It can cause constipation, leakage or both, and is managed with a planned bowel program, medicines and sometimes irrigation.

Can bowel dysfunction be cured?

It depends on the cause. Constipation from diet or medicines and dyssynergic defecation often resolve with treatment and biofeedback. Nerve damage is usually permanent, but a good bowel program allows predictable, controlled emptying for most people.

Why do I have bowel problems after surgery?

Surgery on the rectum, anus or pelvis can affect the storage capacity of the rectum, the sphincter muscles or the nerves. After rectal cancer surgery, many people have frequency and urgency called low anterior resection syndrome. Pain medicines like opioids also cause constipation after any surgery.

Who treats bowel dysfunction?

Your primary care doctor can start treatment. Specialists include gastroenterologists, colorectal surgeons, continence nurses and pelvic floor physical therapists. People with spinal cord injury usually manage it with their rehabilitation team.