White Blood Cells (WBC), Stool

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Turnaround Time: 2 - 7 days
CPT Code:


Test Type: 1 gram Stool


Assist in the differential diagnosis of diarrheal disease.

Ten percent to 15% of stools that yield an invasive bacterial pathogen have an absence of fecal leukocytes. Fecal leukocytes are present in idiopathic inflammatory bowel disease.

Conditions associated with marked fecal leukocytes, blood and mucus include diffuse antibiotic associated colitis, ulcerative colitis, shigellosis, salmonellosis, Campylobacter, and Yersinia infection. Salmonella typhi may evoke a monocyte response. Conditions associated with modest numbers of fecal leukocytes include early shigellosis involving small bowel, antibiotic associated colitis, and amebiasis. Conditions associated with an absence of fecal leukocytes include toxigenic bacterial infection, giardiasis, and viral infections. In a review the methylene blue stain for polymorpholeukocytes had a high sensitivity 85% and specificity 88% for bacterial diarrhea (Shigella, Salmonella, Campylobacter). Positive predictive value was 59%. Negative predicative value was 97%. Combined with a history of abrupt onset, greater than four stools per day and no vomiting before the onset of diarrhea the stool methylene blue stain for fecal polymorphonuclear leukocytes was a very effective presumptive diagnostic test for bacterial diarrhea.1 A positive occult blood test may also be suggestive of acute bacterial diarrhea. Neither method is sufficiently sensitive or specific to preëmpt the use of culture.2 Similar findings including a sensitivity of 81% and specificity 74% were observed when both tests were positive.3

1. DeWitt TG, Humphrey KF, McCarthy P. Clinical predictors of acute bacterial diarrhea in young children. Pediatrics. 1985 Oct; 76(4):551-556. PubMed 4047797

2. Paccagnini S, Fontana M, Ceriani R, et al. Occult blood and faecal leukocyte tests in acute infectious diarrhea in children. Lancet. 1987 Feb 21; 1(8530):442. PubMed 2880230

3. Seigel D, Cohen PT, Neighbor M, et al. Predictive value of stool examination in acute diarrhea. Arch Pathol Lab Med. 1987 Aug; 111(8):715-718. PubMed 3632285

Bishop WP, Ulshen MH. Bacterial gastroenteritis. Pediatr Clin North Am. 1988 Feb; 35(1):69-87 (review). PubMed 3277134

Harris JC, Dupont HL, Hornick RB. Fecal leukocytes in diarrheal illness. Ann Intern Med. 1972 May; 76(5):697-703. PubMed 4554412

Collection Details:

Collection Instructions:

Parasite (O & P) transport (PVA) vial only.

Maintain specimen at room temperature.