Pelvic radiotherapy Radiotherapy has a profound effect on the intestinal mucosa and the highly proliferative tissue. Radiation creates changes in bacterial flora, vascular permeability of the mucosa and intestinal motility. The villi retract and shorten within a few days from the beginning of the treatment and total disappearance may result. The result is a flat surface covered by thin columnar epithelial cells which may also be lost leading to ulcerated surface. Within three to ten days the intestinal epithelium may be completely denuded and the villous surface is replaced by a layer of exudate in which masses of bacteria are present.
Bacteria can penetrate the damaged villi leading to bacteraemia in extreme cases.
Clinically, the primary reactions start during early weeks of treatment giving such symptoms as nausea, vomiting and diarrhoea. The late secondary reaction, eg, fibrosis and obstruction of the intestine, may give clinical symptoms years after. The relationship between early and late reactions is not clear, although some studies have indicated that the severe early reactions precede serious late effects. Lactobacillus supplementation in lethally irradiated mice has been reported to prolong their survival. 29 Figure 1.