Internal Medicine

0521779407-18 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 8:1

1262 Radiation Enteritis and Colitis

RADIATION ENTERITIS AND COLITIS

ALVARO D. DAVILA, MD

history & physical

History of Exposure

■Radiation injury depends on type and quantity of radiation energy

delivered

■SI unit for measuring a dose of radiation: gray (Gy); one gray (Gy)

equals 1 joule of energy deposited in 1 kg of tissue; 1 Gy=100 rads

■Small intestine most vulnerable to radiation injury

➣Risk factors for radiation enteritis:

➣lack of mobility of the distal ileum and cecum, previous abdom-

inal surgery, atherosclerotic vascular disease, lean body habitus,

chemotherapy and other drugs

➣Minimal tolerance dose is 45 Gy

■Colon relatively radioresistant but incidence of colonic radiation

injury greatest

➣Risk factors for radiation colitis:

➣high radiation doses for pelvic tumors, relative immobility of

rectum and sigmoid colon; Minimal tolerance dose is 45 Gy for

colon and 55 Gy for rectum

Signs and Symptoms

■Acute injury to the small intestine and colon frequent, dose depen-

dent and usually transient

■Chronic radiation enteritis appears far less frequently (average inci-

dence of 6%)

➣Onset of symptoms variable and latent (usually 1–2 yr, up to

20 yr after treatment)

➣Chronic bowel injury from ischemia and progressive fibrosis/

atrophy, leading to stricture, obstruction, bacterial overgrowth,

ulceration, fistulization, recurrent infection, and perforation

➣Chronic radiation colitis/proctitis from 5–15% of patients after

pelvic irradiation for prostate, cervical, uterine, bladder, and tes-

ticular cancer

■Early symptoms and signs (acute injury, reversible)

➣Small intestinal injury: nausea, vomiting, abdominal cramping,

and watery diarrhea

➣Colonic and/or rectal injury: tenesmus, diarrhea, mucorrhea,

and rarely hematochezia