Fecal Occult Blood Testing
Let’s move to the indication of colorectal cancer screening, and first consider the target lesions. These ideally include curable stage cancer as shown here, advanced adenomas (this is usually referring to precursor lesions larger than or equal to 1cm and most likely to progress), and….as is increasingly apparent….serrated polyps. Serrated polyps are precursors to roughly 30% of colorectal cancers, typically right-sided, aggressive in their behavior (with perhaps a more rapid growth and progression rate than adenomas), and inconspicuous on colonoscopy. This is a picture of a serrated polyp. One can hardly see this flat, flesh-colored lesion. That is it. To treat these lesions safely, it often requires a submucosal injection of saline before they are removed by incision. Importantly, these lesions have often been ignored in screening trials, and while there are no data reported on their bleeding rates, given their morphology, it is unlikely that they will be detected by fecal blood testing.
CRC Screening: Target Lesions
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)
- 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