RESUMEN
78 patients with rectal adenocarcinoma were studied with a diagnostic protocol in order to obtain a TNM clinical stage in the preoperative period. Each patient underwent digital rectal examination, proctoscopy, double contrast barium enema, pelvic CT scan, liver ultrasound and chest x-ray. The degree of infiltration of the rectal wall by the tumor and the presence or absence of node and liver metastases were evaluated. After resection all specimens were studied by a pathologist who defined the pathologic stage. Data obtained by each diagnostic procedure were compared with the pathologic data. For each method, accuracy, specificity and sensitivity were evaluated. Each method showed an equivalent accuracy (100%) to detect infiltration of the muscularis of the rectum. Data were less accurate in identifying extraparietal tumor invasion. Accuracy was 79% for rectal examination, 74% for double contrast barium enema and 72% for pelvic CT scan. In the evaluation of lymph-node involvement, accuracy was 77%, specificity 74% and sensitivity 80%. Liver metastases were detected with 94% accuracy, 97% specificity and 50% sensitivity.