T–Z

toxic megacolon A serious condition in which a
loss of MUSCLEtone in the lowerCOLON(typically
the sigmoid colon) causes the preceding segment
of colon to greatly enlarge (dilate). Air accumu-
lates in the dilated bowel, increasing the pressure.
Without prompt treatment intestinal perforation
(rupture) is highly likely, with consequential PERI-
TONITIS.

Toxic megacolon is a potentially life-

threatening condition that requires

emergency medical treatment and

often surgery.

Toxic megacolon is usually a complication of
inflammatory conditions affecting the gastroin-
testinal tract, such as INFLAMMATORY BOWEL DISEASE
(IBD) or INFECTION(COLITIS). The congenital disorder
HIRSCHSPRUNG’S DISEASE, in which the lower colon
lacks nerves, can cause toxic megacolon in a new-
born infant.

Symptoms and Diagnostic Path
A person who has toxic megacolon is very sick.
Usually there is FEVERalong with ABDOMINAL DIS-
TENTION, rigidity, and PAIN. REBOUND TENDERNESSand
absence of BOWEL SOUNDSare common findings.
The person may be in SEPTICEMIA(septic SHOCK),
indicating PERITONITIS. The doctor often can make
the diagnosis with an abdominal X-RAYthat shows
the dilated colon.

Treatment Options and Outlook
ANTIBIOTIC MEDICATIONS, CORTICOSTEROID MEDICATIONS,
depending on the cause of the condition, and
intravenous fluids to counter DEHYDRATIONmay
help stabilize the colon, in combination with posi-
tional changes to attempt to move air (intestinal

gas) out of the bowel to help relieve the disten-

tion. Surgery to remove the dilated segment of

bowel (colectomy) is often the only treatment to

prevent or treat bowel perforation. The surgeon

then connects the two healthy ends of bowel

together to restore normal bowel function. With

prompt and appropriate treatment, many people

make a full recovery from toxic megacolon. How-

ever, it does present a serious challenge to the

body’s HEALINGabilities. As well, any underlying

conditions that precipitated the bowel dilation

may continue to cause symptoms.

Risk Factors and Preventive Measures

The primary risk factor for toxic megacolon is any

condition that causes INFLAMMATIONof the colon.

Taking medications to slow gastric motility (such

as to treat DIARRHEA) may contribute to the cir-

cumstances resulting in toxic megacolon. Anyone

who has colitis, GASTROENTERITIS, DIVERTICULAR DIS-

EASE, CELIAC DISEASE, IBD, or other inflammatory

condition affecting the gastrointestinal tract who

experiences symptoms that could suggest toxic

megacolon should see a doctor without delay.

See also ILEUS; SHORT BOWEL SYNDROME.

tube feeding See ENTERAL NUTRITION.

ulcer See PEPTIC ULCER DISEASE.

ulcerative colitis See INFLAMMATORY BOWEL DIS-

EASE(IBD).

virtual colonoscopy See COLONOSCOPY.

vomiting The forceful expulsion of contents

from the STOMACH, also called emesis. The force of

vomiting may also draw digestive material from

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