Histologic features of a bowel preparation:
(1) edema of the lamina propria
(2) extravasation of red blood cells
(3) patchy mucin extravasation
(4) flattening of the surface epithelium and/or stripping away of the surface epithelium (aphthoid mucosal lesion)
(5) patchy mononuclear infiltration in the upper lamina propria
(6) variable low-grade neutrophilic infiltrate in the lamina propria, surface epithelium and/or crypts
(7) variable apoptosis
(8) variable epithelial cell proliferation in gland crypts
Factors increasing the presence of neutrophils after preparation changes:
(1) increased interval between bowel preparation and colonoscopy
(2) mucosal trauma during the colonoscopy
(3) irritating preparation solution
Oral sodium phosphate bowel preparation should be avoided if possible when evaluating patients with low-grade colitis with subtle histologic findings (graft-vs-host disease, Crohn’s disease).
