Fecal Incontinence in Women: Causes and Treatment

Pathophysiology & Diagnostic Tests

Fecal incontinence results when the pressure in the rectum exceeds anal sphincter pressure. Coughing or lifting can transiently increase intra-abdominal pressure and result in stool leakage if the sphincter is weak, and obesity may cause a chronic increase in intrarectal pressure. Forceful propulsion of stool into the rectum and/or loose stools may also overwhelm weak sphincter muscles as a result of infectious diarrhea or chronic conditions, such as irritable bowel syndrome (IBS). The strength of pelvic floor muscles can be affected by injuries to pelvic floor muscles, such as those sustained during childbirth, or by neurological disorders, such as diabetic neuropathy or spinal cord injury that affect the innervation of pelvic floor muscles. In addition, loss of the ability to perceive any increases in rectal pressure can result in a failure to contract pelvic floor muscles at appropriate times to prevent incontinence.

To state these pathophysiological observations more generally and in a way that provides a guide to diagnostic assessment, continence for stools depends on four main factors: rectal sensation, rectal storage capacity, anal sphincter strength and stool consistency. If any of these is compromised, FI can occur.^[7] The first three factors are dependent on the structural integrity and innervation of the rectum, anus and adjoining pelvic floor muscles, whereas stool consistency is determined by the motility (contractions) of the colon. In any one patient, multiple mechanisms may be involved^[7] so diagnostic evaluation should take all of these factors into account.

Standard diagnostic tests include anorectal manometry (pressure measurements in the anal canal and rectum) to assess pelvic floor muscle strength, rectal sensation and rectal compliance, and anal canal ultrasound to assess structural defects in the anal sphincters. Other diagnostic tests that may complement these standard tests include needle electromyography (EMG)^[32] or surface EMG of the anal canal,^[33] or pudendal nerve latency studies (pudendal nerve terminal motor latency)^[34] to assess the integrity of pudendal nerves innervating the pelvic floor. Pelvic MRI is sometimes substituted for anal canal ultrasound.^[35] These tests permit objective assessment and help to plan focused therapy.^[36] More detailed descriptions of the physiological mechanisms responsible for the maintenance of continence and the diagnostic tests used to determine which factors are important in a specific patient are available elsewhere.^[7,37]

No writing assistance was utilized in the production of this manuscript.

Cite this: Fecal Incontinence in Women: Causes and Treatment - Medscape - Sep 01, 2008.

Sidebar: Executive Summary

Fecal Incontinence (FI) is a common medical condition affecting up to 15% of women.

It significantly impairs the lifestyle of women and has a tremendous negative impact on social interactions and self-image, resulting in poor quality of life, work absenteeism and self-imposed isolation and depression.

The physiological mechanisms that maintain continence are adequate strength in the pelvic floor muscles to hold back a bowel movement, adequate compliance of the rectum to be able to store stool between bowel movements, ability to sense rectal filling and normal stool consistency. Deficits in any of these may contribute to FI and, in any given patient, the etiology may be multifactorial.

Risk factors that are unique to women include obstetric trauma (instrumental vaginal delivery, prolonged second stage of labor, large neonatal birthweight and occipito-posterior presentation) and hysterectomy. Other risk factors common to both men and women include chronic diarrhea or urgency, obesity and older age. Systemic diseases that increase the risk of FI are irritable bowel syndrome and diabetes, and many neurological disorders increase the risk of FI. Urinary incontinence is a frequently associated condition.

Primary prevention strategies include reducing the incidence of diarrheal diseases through public health measures, discouraging routine use of episiotomies and internal anal sphincter myectomies, encouraging the use of pelvic floor exercises immediately after childbirth and decreasing obesity. Secondary prevention hinges on increasing the willingness of patients to consult their doctors about FI and the willingness of physicians to screen for FI. Conservative treatment measures that are effective are already available.

The role of elective cesarean section to prevent FI is controversial.

Treatments range from education and conservative medical management to biofeedback and surgery. Conservative treatment emphasizes normalization of stool consistency with antidiarrheal drugs or laxatives and encouragement of pelvic floor exercises. Biofeedback aims to strengthen pelvic floor muscles and improve perception of rectal sensations. The most common surgical options are sphincteroplasty, injection of bulking agents to improve resting pressure in the anal canal and colostomy. Sacral nerve stimulation is an experimental approach that appears promising.

It is important to sensitize general practitioners to this under-recognized condition with a high prevalence. Since effective therapies are available, clinicians who care for postpartum and elderly women should routinely screen for FI and offer evaluation and treatment to women with FI.

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