Radiation-induced intestinal lesions - Symptoms

Symptoms of radiation enteritis may appear quite early, during radiation therapy; sometimes soon after treatment, but their development is also possible several months or even years after its completion. Nausea, vomiting, bowel disorder in the form of diarrhea or constipation may be observed early. Involvement of the large intestine in the pathological process is due to tenesmus, the appearance of mucus and scarlet blood in the feces as a result of the formation of ulcers in the mucous membrane of the lower section of the intestine (10% of cases), the predominance of diarrhea at first, then constipation due to the early occurrence of strictures of the colon or rectum. The predominance of signs of small intestine damage in the clinical picture at an early stage is characterized by cramping abdominal pain, nausea, increased peristalsis, watery stool, bloating, rumbling, and transfusion. Sometimes these symptoms disappear rather quickly, but in some cases they remain for a long time or recur several months after irradiation. Radiation diarrhea develops mainly due to a decrease in the reabsorption of bile acids by the damaged mucous membrane of the ileum, which inhibits the reabsorption of water by the colon. Reactive inflammation of the mucous membrane of the small intestine is accompanied by a disorder of membrane digestion, dysbacteriosis. Depletion and impaired maturation of the absorptive cells of the villi leads to a decrease in the activity of the enzymes of the "brush" border. A breath test can detect a violation of the absorption of lactose, D-xylose, glycocholates, vitamin B12. Moderate disorder of fat absorption is possible, more often in the acute period. However, an asymptomatic course of the disease has also been described even with significant damage to the intestinal mucosa.

The absence of acute, early signs of intestinal damage does not guarantee against the appearance of late, radiation-induced changes. The latent period, i.e. the interval between the time of irradiation and the appearance of signs of intestinal damage, varies within very wide limits - from 3 months to 31 years. The frequency of late intestinal manifestations of radiation therapy is approximately 10%. During this period, the most characteristic symptom of radiation enteritis is colicky abdominal pain caused by partial small intestinal obstruction, which sometimes develops into complete obstruction. Nausea, vomiting, signs of malabsorption of varying degrees may be observed. Intestinal obstruction is usually caused by local mechanical narrowing of the intestine, but may be due to the presence of non-functioning sections of it, preventing normal peristalsis. Simultaneous involvement of many intestinal segments may occur. Clinical examination of the patient reveals signs of intestinal obstruction and dense formations in the abdominal cavity that can be palpated, the appearance of which is associated with inflammation of the intestine and mesentery. Fistulas may form between the pelvic organs and the abdominal organs. In such cases, symptoms such as cloudy vaginal discharge, pneumaturia, and rapid appearance of undigested food in loose stools occur. Evidence of the formation of a rectovaginal fistula is the appearance of signs of proctitis. Abscesses are usually localized in the small pelvis and can lead to peritonitis and sepsis. Perforation of the ileum and colon, although observed relatively rarely, can also be a cause of acute peritonitis. Massive intestinal bleeding caused by ulcerations of the ileum and colon is rarely noted.

In cases of extensive small intestinal involvement, signs of malabsorption syndrome come to the forefront of the clinical picture. In such patients, along with significant, recent, unexplained weight loss, intestinal absorption is indicated by such tests as fecal fat determination, vitamin B12 absorption, bile acid breath test, and D-xylose absorption. Bile acid absorption impairment contributes to both diarrhea and steatorrhea.

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