Editing Radiation bowel injury (section)

== '''Pathophysiology''' ==

* Acute
** Free radicals causing direct      inflammation
** Effects seen within hours -      leucocyte infiltration, ulceration
* Subsequent effects
** Most important effect of      acute injury is to damage mucosal stem cells, which leads to a long-term      reduction in cellular reserves for intestinal villi. Mucosal denudation      occurs, with shortened villi and decreased absorptive area.
** Progressive obliterative      vasculitis, and collagen deposition and fibrosis in submucosa
** Small bowel becomes      thickened due to chronic inflammation and ischaemia
** Telangiectasias can be      present due to disordered revascularisation, causing bleeding
* Chronic outcomes on bowel     function
** End up with impaired normal      absorption and transit - particularly B12 and bile salts due to impact on      ileum, and subsequent bile salt diarrhoea
** Commonly leads to strictures      with obstructive symptoms, or small bowel fistulas
** Risk of malignancy as a late      consequence of radiation injury