Fecal Incontinence

Functional fecal incontinence

Diagnostic criteria:

1. Recurrent uncontrolled passage of fecal material in an individual with a development age of at least 4 years and one or more of the following:

(a) Abnormal functioning of normally innervated and structurally intact muscles

(b) Minor abnormalities of sphincter structure and/or innervation

(d) Psychological causes

2. Exclusion of all the following:

(a) Abnormal innervation caused by lesion(s) within the brain, spinal cord, or sacral nerve roots, or mixed lesions, or as part of a generalized peripheral or autonomic neuropathy

(b) Anal sphincter abnormalities associated with a multisystem disease

Subtypes	Mechanism
Passive incontinence	Loss of rectosigmoid perception and/or impaired rectoanal reflexes. Internal sphincter weakness or tear
Urge incontinence	Disruption of the external sphincter function. Altered rectal capacity
Fecal seepage	Incomplete evacuation of stool, and/or impaired rectal sensation. Normal sphincter function

Reference [7]

Risk Factors

Many factors (see Table 19.2) contribute to impaired continence, including liquid stool consistency, female gender, advanced age, and multiple childbirths. Diarrhea is by far the greatest risk factor for FI. Rectal urgency is a primary risk factor. The incidence of FI increases significantly with age, mostly due to weak pelvic floor musculature and decreased anal resting tone. Parity is associated with frequent sphincter defects due to trauma during delivery. Fecal incontinence and operative or traumatic vaginal delivery are associated, but the literature does not support a benefit of cesarean delivery over nontraumatic vaginal delivery for preserving pelvic floor health or continence.

Table 19.2

Risk factors for fecal incontinence

• Advanced age

• Female gender

• Pregnancy

• Birth trauma

• Perianal surgery or trauma

• Neurologic dysfunction

• Inflammation

• Hemorrhoids

• Pelvic organ prolapse

• Congenital anorectal abnormality

• Obesity

• Post-bariatric surgery

• Limited mobility

• Urinary incontinence

• Smoking

• COPD

Obesity is a risk factor for FI. While bariatric surgery is an effective treatment for morbid obesity, post-bariatric surgery patients frequently have increased FI due to changes in stool consistency.

In younger women, FI is strongly associated with functional bowel disorders, including irritable bowel syndrome. Causes of FI are manifold and may overlap. A sphincter injury may remain asymptomatic for years until age- or hormone-related changes, such as muscle or tissue atrophy, prevent continued compensation.

Clinical Evaluation

A detailed history and focused rectal exam are important to diagnose and determine FI contributing causes. The history should include an evaluation of medications and dietary habits that may alter bowel frequency and stool consistency. A bowel diary can be helpful. It should include the number of episodes of FI, the type of incontinence (gas, liquid, solid), the volume of incontinence, the ability to sense stool, and symptoms of urgency, straining, and feelings of constipation. Table 19.3 outlines information that should be gathered for a thorough FI evaluation.

Table 19.3

Fecal incontinence history checklist

Medical history

□ Diabetes mellitus

□ Cognitive impairment

□ Neurological disorder—such as stroke, spinal cord disease, Parkinson’s

□ Inflammatory bowel disease

□ Colitis—infectious, ischemic, microscopic

□ Celiac sprue

□ Irritable bowel syndrome

□ Radiation history to perianal area

□ Connective tissue disease

Surgical history

□ Anorectal surgery □ Bariatric surgery

Obstetric history

□ Pregnancy □ Parity □ Prolonged delivery

□ Delivery trauma—episiotomy, tear, forceps

Functional status

□ Limited mobility—use of wheelchair, walker

□ Institutional living

Medication list (not all inclusive)

□ Diarrhea provoking: Laxatives, orlistat, metformin, donepezil, rivastigmine, antibiotics, magnesium, selective serotonin reuptake inhibitors

□ Constipation provoking: Loperamide, diphenoxylate/atropine, opioids, tricyclic antidepressants, calcium channel blockers (verapamil), memantine, calcium

Diet (diarrhea provoking)

□ Prunes, plums, beans, alcohol, artificial sweeteners, lactose-containing foods, caffeine

Bowel pattern and stool consistency

□ Normal bowel pattern—frequency of bowel movements

□ Consistency of stool

□ Variability in stool consistency

□ Urgency—able to arrive to the toilet in time

□ Ability to control the passage of gas or flatus

□ Passage of stool without awareness

□ Volume of stool during episodes of incontinence

□ Need to strain or self-digitate to have a bowel movement

□ Exacerbating or relieving factors

A careful physical examination includes inspecting the perineum for moisture, irritation, feces, scars, anal asymmetry, fissures, and laxity of the sphincter. Confirm the presence of an anal wink and demonstrate that perineal sensation is intact. Note the degree of perineal descent, bulging or prolapse of the rectum with bearing down, and the presence of prolapsed or thrombosed hemorrhoids. Digital rectal examination is critical for identifying anatomic abnormalities. Sharp, knifelike pain suggests active mucosal injury such as an acute or chronic fissure, ulcer, or infection. Lax or intense anal tone at rest and with bearing down provides clues to pelvic floor disorders. A neurological evaluation should assess cognition, strength, and gait.

Diagnostic Studies

Specific guidelines delineating when testing should be done do not exist. Clinicians should weigh the risk, benefit, cost, and burden of testing against empiric treatment. Consider a patients’ ability to participate in testing, comorbidities, and potential diagnostic yield of the study. Diagnostic testing can aid in the following clinical scenarios: (1) presumed sphincter injury, (2) overflow incontinence, (3) pelvic floor dysfunction, (4) rapid colonic transit as a cause of diarrhea, (5) significant discrepancy between the history and the physical examination, and (5) elimination of other etiologies.

Endoanal ultrasound is the standard for identifying anal sphincter injuries. It provides excellent resolution of the internal sphincter but is less accurate with the external sphincter. Anal sphincter MRI provides superior spatial resolution of the internal and external sphincter.

Anorectal manometry quantifies internal and external anal sphincter function, rectal sensation, and compliance. Anal resting and squeeze pressures are often low in FI, suggesting weak internal and external sphincters. Patients with normal anal pressures may have other factors, including loose stool, fecal seepage, or altered sensation contributing to FI. The rectal balloon distension test measures rectal sensation and compliance by assessing sensory-motor responses to incremental volumes of air or water. Sensation may be normal, reduced, or increased in FI patients.

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