What is the Meaning of a Positive Hemoccult?
ABSTRACT & COMMENTARY
Synopsis: In patients with a positive fecal occult blood, in whom iron deficiency anemia and active bleeding had been excluded, upper gastrointestinal lesions were identified more frequently than colonic lesions.
Source: Rockey DC, et al. N Engl J Med 1998;339:153-159.
Rockey and colleagues set out to investigate the prevalence of lesions in the upper gastrointestinal tract among patients with positive guaiac-based fecal occult blood tests and determine the correlates of positive endoscopic findings. During a period of 30 months, they prospectively studied all patients with at least one stool specimen positive on fecal occult blood testing and referred for further evaluation. Patients with documented iron deficiency anemia or active gastrointestinal bleeding were excluded from the study. All participants had a detailed history taken and underwent colonoscopy followed by esophago-gastro-duodenoscopy. Of the 310 potentially eligible patients, 248 (40% women; mean age, 61 years) were studied. In 48%, they identified lesions consistent with occult bleeding. Of these 119 patients, 71 were found to have lesions in the upper gastrointestinal tract and 54 in the colon; six had abnormalities in both areas. The most common upper gastrointestinal lesions were esophagitis (23 patients), gastric ulcer (14), gastritis (12), and duodenal ulcer (10). Thirty of these patients were long-term users of aspirin, ethanol, or NSAIDs. In the colon, the most common lesions were adenomas greater than 1 cm in diameter (29), carcinoma (13), colitis (5), and vascular ectasia (5). The authors concluded that, in patients with a positive fecal occult blood, in whom iron deficiency anemia and active bleeding had been excluded, upper gastrointestinal lesions were identified more frequently than colonic lesions.
COMMENT BY EAMONN M.M. QUIGLEY, MD
Hemoccult testing of stool is employed in screening for colon cancer. False positive tests represent a problem. It has been suggested that upper gastrointestinal lesions do not contribute significantly to this phenomenon because blood from the upper gastrointestinal tract is degraded by the time it reaches the colon and, therefore, does not provide a positive guaiac-based test. This carefully performed study suggests quite the reverse. Indeed, in these patients referred for evaluation of hemoccult-positive stools, not only were upper gastrointestinal symptoms common when they were subjected to a structured interview, but upper gastrointestinal lesions were commonly identified at endoscopy. Furthermore, NSAID use was common among these patients. The first clinical point, therefore, is the importance of re-reviewing the clinical history, including the use of medications, in the patient in whom a hemoccult-positive stool is detected. This may yield significant symptoms and a history of relevant medication use. Second, this confirms the significant yield, in terms of large polyps and colon cancer, among patients with a hemoccult-positive stool. The prevalence of these lesions, at 12.7% and 4.5%, respectively, is similar to that of other studies.
These authors also examined the comparative yield of hemoccults detected by screening and by digital rectal examination. Contrary to some prior data, they found that the positive hemoccult on digital rectal examination was, if anything, most sensitive in detecting lesions. A third clinical point, therefore, is that one should not discard the results of a positive hemoccult obtained on digital rectal examination. What is the bottom line in terms of performing endoscopy in these patients? Should they all be submitted to both colonoscopy and esophago-gastro-duodenoscopy-a managed care nightmare?
While upper gastrointestinal symptoms were more common among these patients and were more likely to be associated with lesions in the upper gastrointestinal tract, they were by no means sufficiently sensitive or specific to guide endoscopy. For the moment, therefore, it seems reasonable to take symptoms into account in deciding on evaluation for these patients. However, given the long-term significance of polyps and cancer, in comparison to the lesions identified in the upper gastrointestinal tract, it seems most prudent to first and foremost perform colonoscopy. If colonoscopy does not reveal a lesion to explain the occult blood loss and/or upper gastrointestinal symptoms are present, upper gastrointestinal endoscopy is indicated.
References
1. Geller AJ, et al. The high frequency of upper gastrointestinal pathology in patients with fecal occult blood and colon polyps. Am J Gastrointerol 1993;88:1184-1187.
2. Zuckerman G, Benitez J. A prospective study of bi-directional endoscopy (colonoscopy and upper endoscopy) in the evaluation of patients with occult gastrointestinal bleeding. Am J Gastrointerol 1992; 87:62-66.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content