Fecal Occult Blood Testing
Colorectal cancers do bleed…but bleeding is often intermittent and, at times, absent. In a study we conducted on 10 patients with colorectal cancer in whom fecal blood levels were quantified by HemoQuant and also tested by Hemoccult over a 2 week intensive collection period, this point is illustrated. Fecal blood levels commonly fell within the normal range of <2mL/day as shown in the blue shaded area, and Hemoccult was positive in only 3 patients. The positive patients were the green circles, the negative were the blue circles. In patients with hemorrhagic cancers, high fecal blood levels may be expected as shown here….but, in those with normal levels, small nonhemorrhagic tumors are more likely. An important take home point is that occult blood, however well measured, is an imperfect and inconsistent marker for colorectal neoplasia.
Occult Bleeding From Colorectal Cancer
Jump to section:
- Occult Gastrointestinal (GI) Bleeding: Definition
- Quantity of GI Bleeding Required to "See" Blood in Stool
- Fecal Occult Blood Tests
- Why Detect Occult GI Bleeding?
- Causes of Fe Deficiency in Industrialized Countries (Average %)
- Causes of Occult GI Bleeding
- Fecal Detection of Ingested Blood
- Iron Deficiency or Anemia: Which Test?
- CRC Screening: Target Lesions
- Occult Bleeding From Colorectal Cancer
- Fecal Blood Testing for Colorectal Cancer (CRC)
- Microscopic Examination: Biopsy
- FOBT Screening
- Stool Test Detection of CRN in Screen Setting
- Laboratory Testing vs Office Digital Rectal Exam (DRE)
- Evaluation of Fecal Immunochemical Testing (FIT) Assays
- FIT Specificity
- CRC Screening by FOBTs
- CRC Screening Guidelines*
- CRC Screening: Which Fecal Blood Test?
- Soft Indications for FOBT Use?
- Fecal Occult Blood Tests Summary
- Mayo Medical Laboratories Tests