Fecal incontinence refers to passage of stool into the underclothing, or other inappropriate places. Fecal incontinence commonly accompanies functional constipation, when liquid stool leaks out as the child attempts to pass gas.
Fecal incontinence without fecal retention occurs when someone has diarrhea, as the muscles of the bottom fatigue and cannot hold back anymore.
Non-retentive fecal incontinence is the diagnosis applied to children with a developmental age of at least 4 years, who have bowel movements in places and at times that are inappropriate, at least once a month for at least 2 months, in the absence of a disease to explain it, and without signs of fecal retention. About one in ten incontinent children has non-retentive fecal incontinence. The rest have functional constipation.
Most children with non-retentive fecal incontinence have bowel movements daily during waking hours, and do not complain of constipation. Soiling may be in small amounts, or consist of an entire bowel movement. In contrast to children with functional constipation and incontinence, children with non-retentive incontinence do not hold back their BMs and do not accumulate a big stool.
Sometimes non-retentive fecal incontinence is caused by an emotional disturbance in a school-aged child. Often the soiling episodes have a relationship to a person or time of day, because defecation may be triggered by anger in children who meet diagnostic criteria for oppositional-defiant disorder or conduct disorder.
Treatment goals are to help the parent to understand that there is no medical disease, and to accept a referral to a mental health professional. Parents need guidance to understand that incontinence is a symptom of emotional upset, not simply bad behavior.
Figure 1: Normal Stooling vs. Witholding of Stool
A. The rectum is empty. There is no urge to defecate.
B. Stool enters the rectum and stretches the rectal wall, causing a sensation of fullness.
C. Rectal wall distention causes relaxation of the internal anal sphincter, allowing the stool to descend into the proximal anal canal. This movement causes awareness that stool passage is imminent.
D. The pelvic floor muscles contract to maintain continence, moving the stool upward and out of the anal canal.
E. If the stool remains in the rectum after the pelvic floor returns to its resting state, then stool will no longer be in contact with the anus. The rectal wall relaxes; reducing the pressure and wall tension, and the urge to defecate abates.
F. Defecation occurs when the pelvic floor relaxes, and the pressure in the rectum is greater than pressure from the external anal sphincter and the pelvic floor. Stool moves from the region of higher pressure to the area of lower pressure. The accompanying increase in intra-abdominal pressure propels stool through the anus.
G. The pelvic floor contracts again when stool is no longer in contact with the anus, and this forces out any remaining stool.
H. If a child repeatedly responds to the urge by withholding (C and D), a fecal mass accumulates. Over time the fecal mass becomes too large and too firm to be extruded without painful stretching of the anus. The mass is too bulky to be shifted out of contact with the anoderm lining of the anal canal. As pelvic floor muscles fatigue, the anus becomes less competent and retentive fecal soiling with soft or liquid stool occurs. The child resorts to retentive posturing, attempting to preserve continence by vigorous contraction of the gluteal muscles. Everyone passes gas about 20 or 30 times a day. The sensitive lining of the rectum can tell between gas and a big, hard stool. Also, the lining can tell between liquid and a big, hard stool. But, the lining of the rectum cannot sense the difference between liquid and gas, so that sometimes children relax their bottoms for just a second to let gas out, but liquid stool leaks out, too.
Adapted from IFFGD Publication: Childhood Defecation Disorders: Constipation and Stool Incontinence #810 by Paul E. Hyman, MD, Professor of Pediatrics, Louisiana State University; Chief Pediatric Gastroenterology, Children’s Hospital, New Orleans, LA.