RESUMO
Screening programs for colorectal cancer (CRC) are standard in most developed countries because they reduce mortality and are cost-effective. Within them, colonoscopy allows to directly visualize the colon and remove neoplastic lesions. However, it is an expensive exam with low adherence in asymptomatic individuals. The fecal occult blood test (FOBT) is a low-cost and risk-free method for the user, which results in a high rate of adherence, explaining its use in most screening programs. This article analyzes the effectiveness of different fecal occult blood tests in screening programs. The main conclusions are that the sensitivity of the guaiac-based chemical test for the detection of colorectal cancer is lower than that observed with qualitative and quantitative immunological tests. Automated quantitative methods allow objective readings independent of the operator and the reaction reading time, necessary for the analysis of large numbers of samples. The participation rate with immunological FOBTs is higher than with chemical ones, which is why they are preferred by the different countries that have screening programs. The use of quantitative tests allows stratification of symptomatic and asymptomatic patients at higher risk, in the screening programs.
Assuntos
Humanos , Neoplasias Colorretais/diagnóstico , Sangue Oculto , Programas de Rastreamento , Colonoscopia , Detecção Precoce de Câncer , GuaiacoRESUMO
Occult bleeding of the gastrointestinal tract is a major cause of iron deficiency anemia. Even with endoscopic evaluation of the upper and the lower gastrointestinal tract in these patients, in 30~50% of the cases, the cause of bleeding still remains undiscovered. Wireless capsule endoscopy (WCE) is a novel method of evaluating the small bowel mucosa by using a small capsule equipped with a camera and transmission device. Complications of WCE include impaction within the gastrointestinal tract, sometimes requiring surgical removal. The authors report a case of capsule impaction in the small bowel in a patient evaluated for anemia due to occult gastrointestinal tract bleeding. The patient is a 19 year-old female with a history of anemia since age 4. The stool guaiac test was positive, but upper and lower gastrointestinal tract endoscopy showed no abnormalities, so WCE was done. A short segment of circular ulcers with lumen narrowing were seen in the distal jejunum. Seven days after ingestion of the capsule, the patient denied passage of the capsule. Small bowel enteroclysis was performed, and the capsule was seen along with a segment of lumen narrowing distal to the site of retention. Surgery was done, and upon laparoscopic examination, the entire bowel appeared normal. Retrieval of the capsule was done along with a resection of an 8 cm segment of the small bowel. Three linear ulcers were seen in the resected bowel specimen. Pathology revealed no evidence of Crohn's disease or tuberculosis. The patient is still on iron supplements, but her hemoglobin level remains stable at 11~12 g/dl.