Fecal incontinence
Fecal incontinence, or in some forms, encopresis, is a lack of control over defecation, leading to involuntary loss of bowel contents—including flatus, liquid stool elements and mucus, or solid feces. FI is a sign or a symptom, not a diagnosis. Incontinence can result from different causes and might occur with either constipation or diarrhea. Continence is maintained by several interrelated factors, including the anal sampling mechanism, and incontinence usually results from a deficiency of multiple mechanisms. The most common causes are thought to be immediate or delayed damage from childbirth, complications from prior anorectal surgery, altered bowel habits. Reported prevalence figures vary: an estimated 2.2% of community-dwelling adults are affected, while 8.39% among non-institutionalized U.S adults between 2005 and 2010 has been reported, and among institutionalized elders figures come close to 50%.
Fecal incontinence has three main consequences: local reactions of the perianal skin and urinary tract, including maceration, urinary tract infections, or decubitus ulcers ; a financial expense for individuals, employers, and medical insurers and society generally ; and an associated decrease in quality of life. There is often reduced self-esteem, shame, humiliation, depression, a need to organize life around easy access to a toilet, and avoidance of enjoyable activities. FI is an example of a stigmatized medical condition, which creates barriers to successful management and makes the problem worse. People may be too embarrassed to seek medical help and attempt to self-manage the symptom in secrecy from others.
FI is one of the most psychologically and socially debilitating conditions in an otherwise healthy individual and is generally treatable. More than 50% of hospitalized seriously ill patients rated bladder or fecal incontinence as "worse than death". Management may be achieved through an individualized mix of dietary, pharmacologic, and surgical measures. Health care professionals are often poorly informed about treatment options, and may fail to recognize the effect of FI.
Signs and symptoms
FI affects virtually all aspects of sufferers' lives, greatly diminishing physical and mental health, and affecting personal, social, and professional life. Emotional effects may include stress, fearfulness, anxiety, exhaustion, fear of public humiliation, feeling dirty, poor body image, reduced desire for sex, anger, humiliation, depression, isolation, secrecy, frustration, and embarrassment. Some patients cope by controlling their emotions or behavior. Physical symptoms such as skin soreness, pain and odor may also affect quality of life. Physical activity such as shopping or exercise is often affected. Travel may be affected, requiring careful planning. Working is also affected for most. Relationships, social activities and self-image likewise often suffer. Symptoms may worsen over time.Causes
FI is a sign or a symptom, not a diagnosis, and represents an extensive list of causes. Usually, it is the result of a complex interplay of several coexisting factors, many of which may be simple to correct. Up to 80% of people may have more than one abnormality that is contributing. Deficits of individual functional components of the continence mechanism can be partially compensated for a certain period, until the compensating components themselves fail. For example, obstetric injury may precede onset by decades, but postmenopausal changes in the tissue strength reduce in turn the competence of the compensatory mechanisms. The most common factors in the development are thought to be obstetric injury and after-effects of anorectal surgery, especially those involving the anal sphincters and hemorrhoidal vascular cushions. The majority of incontinent persons over the age of 18 fall into one of several groups: those with structural anorectal abnormalities, neurological disorders, constipation or fecal loading, cognitive or behavioral dysfunction, diarrhea, inflammatory bowel diseases, irritable bowel syndrome, disability related, and those cases which are idiopathic. Diabetes mellitus is also known to be a cause, but the mechanism of this relationship is not well understood.Childbirth
Vaginal delivery causes stretching of the pelvic muscles and the pudendal nerve. Obstetric injury is a leading cause of fecal incontinence. Obstetric injury may tear the anal sphincters, and some of these injuries may be occult. The risk of injury is greatest when labor has been especially difficult or prolonged, when forceps are used, with higher birth weights, or when a midline episiotomy is performed. Only when there is post-operative investigation of FI such as endoanal ultrasound is the injury discovered. Vaginal birth may lead to pudendal nerve damage. The pudendal nerve may sustain irreversible injury if it is stretched more than 12% of its original length. The nerve is especially vulnerable to stretch damage during childbirth because of the course of the nerve, as it runs in close proximity to pelvic muscles and ligaments, before exiting and then re-entering the pelvic cavity. The damage is likely to occur at the exit from the pudendal canal, because the course of the nerve is relatively fixed at this point. Stretching occurs during delivery, especially from the child's head. The risk increases when delivering larger-than-average babies or with prolonged or difficult labour. The risk of damage to the pudendal nerve is also higher if obstetrical forceps are used. 60% of females who sustained obstetric tears were demonstrated to also have pudendal nerve damage. Any damage to the pudendal nerve occurring during childbirth may not become fully apparent until years later, for example at the onset of menopause.Surgery
FI is a much under-reported complication of surgery. The IAS is easily damaged with an anal retractor, leading to reduced resting pressure postoperatively. Since the hemorrhoidal vascular cushions contribute 15% of the resting anal tone, surgeries involving these structures may affect continence status. Partial internal sphincterotomy, fistulotomy, anal stretch, hemorrhoidectomy or transanal advancement flaps may all lead to FI postoperatively, with soiling being far more common than solid FI. The "keyhole deformity" refers to scarring within the anal canal and is another cause of mucus leakage and minor incontinence. This defect is also described as a groove in the anal canal wall and may occur after posterior midline fissurectomy or fistulotomy, or with lateral IAS defects. There is increased risk of FI after radical prostatectomy for prostate cancer.Anal sphincter weakness
The anal canal presents the final barrier to continence. The resting tone of the anal canal is not the only important factor; both the length of the high-pressure zone and its radial translation of force are required for continence. This means that even with normal anal canal pressure, focal defects such as the keyhole deformity can be the cause of substantial symptoms. External anal sphincter dysfunction is associated with impaired voluntary control, whereas internal anal sphincter dysfunction is associated with impaired fine-tuning of fecal control. Defects of the external anal sphincter are associated with urge incontinence. The external anal sphincter is supplied by the pudendal nerve. Damage to the nerve supply of the external anal sphincter on one side may not result in severe symptoms because there is substantial overlap in innervation by the nerves on the other side. The internal anal sphincter receives extrinsic autonomic innervation via the inferior hypogastric plexus, with sympathetic innervation derived from spinal levels L1-L2, and parasympathetic innervation derived from S2-S4. Disruption of the function of the internal anal sphincter results in reduced resting pressure in the anal canal. This is associated with passive leakage.Lesions which mechanically interfere with, or prevent the complete closure of the anal canal can cause a liquid stool or mucous rectal discharge. Such lesions include piles, anal fissures, anal cancer, or fistulae.
Nontraumatic conditions causing anal sphincter weakness include scleroderma, damage to the pudendal nerves, and IAS degeneration of unknown cause.