Definition and Overview
Fecal incontinence, also known as bowel incontinence, is a symptom pertaining to the inability to control defecation. With this condition, bowel contents are expelled from the body involuntarily.
Continence is maintained by a number of factors. Anatomically, the puborectalis muscle and the anal sphincters need to be intact. The puborectalis sling ensures the continence of feces or solid stool, while the internal anal sphincter, along with hemorrhoidal tissues, ensures the continence of liquid stool and gas or flatus. The external anal sphincter, meanwhile, is a muscle that can be voluntarily controlled and contracted when needed. Together with the other muscles of the pelvic floor, they can act to create a barrier and aid in defecation. Physiologically, several reflexes and normal peristaltic movements are responsible for maintaining an individual’s continence. Normal functioning of the nervous system, including the pudendal nerve, which innervates the external anal sphincter, is also necessary. A defect or abnormality in any of these components can result in fecal incontinence.
Fecal incontinence is estimated to occur in approximately 2% of the adult population. It is more common in the elderly, occurring in 45% of individuals living in nursing homes. It is around 8 times more common in females than males and has a higher incidence in women who have given birth.
Cause of Condition
There are many possible causes of fecal incontinence. The causes can be broadly classified as anatomic or neurogenic.
The most common cause is obstetric injury during vaginal delivery. This occurs by two mechanisms: either due to injury or tear of the muscles of the anal sphincter, or due to traction or damage to the pudendal nerve. Muscle tears occur during delivery itself, with a higher risk in patients with fourth-degree lacerations. The performance of an episiotomy and the use of forceps during delivery also increase the risk for developing muscle tears. Damage to the pudendal nerve occurs with traction injury or nerve compression, especially with prolonged delivery. Fecal incontinence in these patients usually occurs years after the injury.
Fecal incontinence can also occur with several congenital abnormalities. Patients with anorectal abnormalities, such as imperforate anus, tend to have underdeveloped pelvic muscles. Although surgical correction can create an anatomically normal anal opening, maintaining adequate control remains to be a challenge, with fecal incontinence occurring in as much as 25% of postoperative patients. Congenital abnormalities of the spinal cord, such as spina bifida, can also result in fecal incontinence.
Trauma to the pelvic area can also cause fecal incontinence, but is relatively uncommon. This is usually due to motor vehicular accidents with associated pelvic injury, spinal injuries and foreign body insertion in the rectum. Iatrogenic injuries can also result in fecal incontinence. This usually occurs with anal or rectal surgery, such as hemorrhoidectomy or fistulotomy. Other causes include rectal prolapse, anal or rectal malignancies, and radiotherapy to the pelvic area.
The severity of fecal incontinence can range from occasional seepage of liquid stool (partial incontinence) to daily involuntary loss of solid stool (complete incontinence). The initial symptom is usually the unintentional leakage of flatus or gas, and symptoms may be progressive. Patients can experience soiling, or liquid discharge from the anal area. Recurrent or constant exposure to this discharge can result in inflammation and irritation of the skin on the perineal area. Patients are noted to have perianal pain or discomfort, excoriations, and itchiness. Approximately half of patients who have fecal incontinence also have urinary incontinence.
Aside from these symptoms, fecal incontinence is associated with social and psychological issues. Most affected individuals tend to hide this complaint and opt to stay at home instead of consulting a medical specialist. Many patients eventually develop depression.
Who to See and Types of Treatments Available
Patients who have fecal incontinence should consult a surgeon, preferably a colorectal specialist. Several examinations, such as endoanal ultrasound, anal manometry and pudendal nerve studies, may have to be conducted to precisely identify the cause.
Initial management of fecal incontinence is conservative. The goals are to improve continence, sphincter function and quality of life. Dietary modification by increasing fiber intake may be helpful. Patients with minor fecal incontinence may benefit from using stool bulking agents, such as psyllium. Constipating medications, such as loperamide and codeine, may likewise be useful. Keeping the rectum empty prevents involuntary stool loss; techniques, which involve the use of suppositories or enemas and colonic irrigation, may be attempted as well. Inflammation or infection of the perianal skin may be treated with topical agents. Therapy with biofeedback has been shown to be effective in patients with partial denervation resulting in incontinence. Pelvic floor exercises are also advised, and may provide slight benefit in some cases.
If fecal incontinence cannot be adequately controlled by conservative measures, then surgical intervention is required. Primary repair is possible for minor sphincter injuries. The most common type of sphincter repair performed is an overlapping sphincteroplasty. In this procedure, the muscles are isolated and mobilized, separating them from surrounding scar and connective tissues. The muscles are then overlapped, attempting to recreate the muscular anal ring. There are a number of other more complicated approaches, depending on the cause of the incontinence. When the sphincter injury is associated with an injury to the rectum, patients may have to undergo fecal diversion and wash-out. Patients with congenital abnormalities may have to undergo a series of surgeries to correct the defect and restore sphincter function.
Advancements in technology have also led to newer approaches in the management of fecal incontinence. These include radiofrequency treatment to enhance collagen fiber formation in sphincter muscles; stimulation of sacral nerves to improve sphincter muscle strength; and placement of an artificial anal sphincter that can be manually controlled.
For the most severe forms of incontinence that cannot be relieved by any other method, placement of a stoma may have to be performed. Creation of a stoma involves exteriorizing part of the large intestines and allowing it to empty through the abdominal wall and into an external bag. This is usually the last resort.
Madoff RD. Diseases of the rectum and anus. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 147.
Rao SSC. Fecal incontinence. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 17.