bowel movements to expel it. Increased fiber in
the diet, stool softeners (medications that help the
stool retain fluid), increased fluid consumption,
and daily physical activity such as walking when
possible can help prevent constipation and fecal
impaction.
See also DIET AND HEALTH; SPINAL CORD INJURY;
TOXIC MEGACOLON.
fecal incontinence Loss of bowel control. Fecal
incontinence occurs more frequently in young
children and in elderly adults, though can occur at
any age. FECAL IMPACTION, in which stool hardens
in the RECTUM, is a common cause of fecal inconti-
nence, particularly in children, as digestive waste
that continues to move through the COLONforces
its way around the impaction and leaks from the
ANUSbecause the rectum has no capacity to store
it. Fecal incontinence also may result from injury
or damage to the nerves that provide sensation to
the perineum and rectal area or that control the
anal sphincter (MUSCLEthat regulates the discharge
of stool). Such injury may be congenital (such as
may occur with SPINA BIFIDAand other congenital
anomalies affecting the SPINAL CORD), the conse-
quence of trauma to the perineal area during
CHILDBIRTH(particularly EPISIOTOMY), a complication
of surgery (such as to treat HEMORRHOIDSor ANAL
FISSURE), or a SIDE EFFECTof RADIATION THERAPYto
treat CANCER.
Though fecal incontinence is more common
among those over age 70, it is not a natural conse-
quence of aging. Treatment can improve or elimi-
nate fecal incontinence in most circumstances.
Treatment may include “retraining” the defecation
response (BIOFEEDBACK), surgery to repair damaged
muscle tissues or a weakened anal sphincter, or
therapies to relieve INFLAMMATORY BOWEL DISEASE
(IBD) and other conditions in which there is
INFLAMMATIONof the colon. Eating more fruits, veg-
etables, and whole grain products adds fiber to the
diet, which improves gastrointestinal motility (the
movement of digestive content through the gas-
trointestinal tract). Regular physical activity, such
as daily walking, also improves gastrointestinal
motility.
See also CONGENITAL ANOMALY; CONSTIPATION; DIAR-
RHEA; DIVERTICULAR DISEASE; FIBER AND GASTROINTESTI-
NAL HEALTH; RECTAL PROLAPSE.
fecal occult blood test (FOBT) A laboratory test
to determine whether there is microscopic (occult)
BLOODin the stool, primarily to screen for COLOREC-
TAL CANCER although other conditions, such as
INFLAMMATORY BOWEL DISEASE(IBD) and diverticulo-
sis, can also cause occult bleeding. Two kinds of
FOBT kits are available for self-sampling at home,
one that a laboratory tests and the other that
shows immediate results.
For the conventional guaiac test, the person
receives a kit from the doctor. The kit contains
three cards onto which the person applies a small
stool sample, one sample each day for three days.
The cards go into a prepaid envelope for mailing
to the laboratory (or may be returned to the doc-
tor’s office). The lab applies a chemical, guaiac,
that reacts with heme, a component of theHEMO-
GLOBINin blood. The reaction produces a blue col-
oration, a positive result. No color change
indicates a negative result (no blood is present).Any positive FECAL OCCULT BLOOD TEST
(FOBT) result requires further medical
evaluation to determine the source of
the bleeding and to rule out serious
conditions such as COLORECTAL CANCER.Tests that show immediate results are available
in most pharmacies and drugstores without a doc-
tor’s prescription. They contain reagent tissues
that the person drops into the toilet following a
BOWEL MOVEMENT (before flushing). The tissue
turns blue-green if there is any heme present,
indicating blood and remains colorless when no
blood is present. As with the conventional test,
the person tests three bowel movements over
three days. The kit includes a card that the person
can fill out and send to his or her doctor or keep
for personal health records.
The FOBT is a good test for colorectal cancer
because the intestinal polyps that are its starting
points bleed easily, though the bleeding often is
not apparent with visual examination of the stool.
Many health conditions can cause positive results,
such as ulcers, DIVERTICULAR DISEASE, HEMORRHOIDS,
and ANAL FISSURE. Certain foods and other sub-
stances can cause false-positive or false-negative
results with guaiac-based tests; test instructions
may advise avoiding them for 48 hours before44 The Gastrointestinal System