RESUMEN
<p><b>OBJECTIVE</b>To study the role of transrectal ultrasound in detecting and deciding rectal cancer margin and surgical incisal edge.</p><p><b>METHODS</b>33 surgical specimens of rectal carcinoma were examined with transrectal ultrasound. Cancerous margin and surgical incisal edge were determined. The results were compared with pathological examination. p53 and K-ras gene mutation as tumor molecular markers of residue cancer cells were detected in incisal edge tissue with PCR-SSCP method.</p><p><b>RESULTS</b>General accuracy for cancer infiltration depth with transrectal ultrasound was 86.6%. For mucosa and submucosa infiltration lesions, the accuracy was 72.7%. For lamina muscularis, the accuracy was 90.9%. And for adventitia and peripheral tissue infiltration of rectum, the accuracy was 88.5% and 100% respectively. No remains of cancer cells and tumor molecular markers were detected at distal incisal edges of 1.0 cm, 2.0 cm and 3.0 cm determined with transrectal ultrasound.</p><p><b>CONCLUSIONS</b>Rectal cancer margine and surgical incisal edge determined with transrectal ultrasound are close to examined by pathology. Transrectal ultrasound is helpful and reliable to define incisal edge in rectal cancer surgery.</p>