becomes continuous. Stools often are watery and
bloody, and may contain large quantities of mucus.
Though intussusception is more common in chil-
dren who have CYSTIC FIBROSISor Meckel’s divertic-
ulum, or who experience blunt trauma to the
abdomen, there are no certain predisposing factors.
BARIUM ENEMA provides the diagnosis, and,
about 75 percent of the time, the treatment as
well because the barium causes the bowel to
expand back out. When the intussusception per-
sists, the situation requires immediate surgery.
Without treatment intussusception rapidly pro-
gresses to PERITONITISand SEPTICEMIA, and usually is
fatal. With appropriate treatment, nearly all
infants experience full and uneventful recovery
with no long-term consequences. Intussusception
typically does not recur.
See also DIVERTICULAR DISEASE.
irritable bowel syndrome (IBS) A constellation
of symptoms that reflect functional disturbance of
the gastrointestinal system. IBS is one of the most
common gastrointestinal disorders that cause peo-
ple to seek medical care, accounting for 10 percent
of doctor visits each year. IBS symptoms are
episodic and may range from mild to debilitating
and typically manifest before age 35 years. IBS
affects three times as many men as women.
Symptoms and Diagnostic PathThe hallmark symptoms of IBS are
- ABDOMINAL PAIN that goes away with bowel
movements - a change in the frequency and nature of bowel
movements (DIARRHEA or CONSTIPATION that
marks a change from usual bowel movements) - mucus in the stool (mucorrhea)
- ABDOMINAL DISTENTIONor sensation of bloating
Periods of exacerbation alternate with periods
of REMISSION. In women, exacerbation may accom-
pany other symptoms of PREMENSTRUAL SYNDROME
(PMS). Stress, emotional or physical, is a significant
catalyst of symptoms for many people who have
IBS. The diagnostic path generally includes the
gamut of gastrointestinal tests, though diagnosis of
IBS relates to the length of time the person has
had symptoms and the frequency with which
symptoms occur. Current diagnostic guidelines
support a diagnosis of IBS when all of these four
symptoms persist for longer than three months
and doctors cannot detect any underlying patho-
logic reasons for the gastrointestinal disturbances.Treatment Options and Outlook
Treatment targets symptoms and may include
ANTIDIARRHEAL MEDICATIONS, ANTICHOLINERGIC MEDICA-
TIONSto slow intestinal motility, and certain ANTI-
DEPRESSANT MEDICATIONS that are successful in
relieving symptoms in CHRONIC PAIN syndromes.
Several medications specifically to treat IBS are
available. There are significant risks and restric-
tions for some of these medications, and current
regulatory and practice standards limit their use to
people whose symptoms fail to respond to other
treatments and interfere with daily living.
Alosetron (Lotronex) Alosetron specifically tar-
gets the neuroreceptors in the COLONto block the
passage of NERVEsignals that cause the colon to
contract. This slows peristalsis only in the colon,
increasing the amount of time digestive matter
remains in the colon so the colon can absorb more
water from it. Alosetron is available only for use
in women who have debilitating diarrhea as the
primary component of their IBS and under strict
guidelines in which the prescribing doctor and the
woman must agree to follow. Alosetron is not
available for men because there is insufficient evi-
dence of its effectiveness in men; clinical research
studies enrolled primarily women. The most sig-
nificant risks of alosetron are severe constipation
that causes bowel obstruction (ILEUS) and ischemic
COLITIS (blocked BLOOD flow to the colon that
results in INFECTION).
Tegaserod (Zelnorm) Tegaserod mimics the
action of serotonin, increasing the response of
serotonin neuroreceptors in the intestinal tract.
Serotonin is a NEUROTRANSMITTERmost commonly
recognized for its role in carrying nerve impulses
related to emotion in the BRAIN. However, 95 per-
cent of the serotonin in the body is concentrated
in the gastrointestinal tract where it facilitates
intestinal motility (peristalsis), gastric acid and
other gastrointestinal fluid secretions, and the sen-
sitivity of cells in the gastrointestinal tract to regis-
ter pain. Like alosetron, tegaserod is available only
for use in women who have debilitating diarrheairritable bowel syndroms (IBS) 65