Laboratory: Hematology
Test Name:
Test Code: SFL
Clinical Information:
This test looks for white blood cells in stoool.  It is used in the diagnosis of inflammatory diarrhea which may be a symptom of an infection caused by bacteria such a shigella, Clostridium difficile, campylobacter, or salmonella.  It may also occur in inflammatory bowel disease, such as Crohn's disease or ulcerative colitis.  Rarely, fecal leukocytes can appear in diarrhea caused by other parasites or viruses, so a negative test result does not rule out a potential problem.  10 - 15% of stool samples with an invasive bacterial pathogen present will test negative for fecal leukocytes.
The test has generally poor sensitivity and specificity and should be performed only on a diarrheal stool (numerous small, loose, or watery stools, blood or mucus in the stool).
Collection Devices:
Specimen Required: Fresh stool sample.  Specimen should be bloody, mucoid, or liquid.  Soft/well-formed stool will be rejected.
Reference Values:
A descriptive report will be sent.
See Also:
More Information:
Slide preparation must be performed within 12 hours of collection.