Differences between surgical colorectal conditions seen in the temperate and tropical regions.

Geographic location of a population plays a significant role in the interpretation of symptoms of some diseases of the colon. Because diverticular disease of the colon is very rare in the tropics, frank rectal bleeding, which may be suggestive of bleeding diverticulosis when it occurs in a temperate region, is suggestive of a bleeding ileal typhoid ulcer eroding terminal branches of the superior mesenteric artery. Similarly, symptoms suggestive of ulcerative colitis in a temperate region are suggestive of amebic colitis in the tropics. Anatomic variation also plays a part in the nature of some disease processes. The high incidence of freely mobile cecum and ascending colon and the freely mobile redundant sigmoid colon, seen in a tropical population, play a part in the frequent occurrence of nontumid intussusception, relatively high incidence of sigmoid volvulus, and relatively high incidence of rectal prolapse seen in the area.