Faster Diagnosis of Amebic Colitis

If your patient complains of diarrhea, bloody mucous stools, or abdominal cramps and he has recently returned from the tropics, immediately consider amebic colitis. Warm wet-field fecal smears and cultures can aid diagnosis, but the microscope method is quicker and more accurate.

If you find mucosal ulcers during a sigmoidoscopic or proctoscopic examination, make direct mucosal smears of the of the ulcer margin and examine them microscopically. Look for Entamoeba histolytica, a mobile trophozoite, 6 microns to 40 microns in diameter, with clear hyaline unidirectional pseudopods containing ingested red blood cells. E histolytica may be confused with Escherichia coli, the normal inhabitant of the intestine, except that E coli never contain phagocytized red blood cells.