Staging of rectal cancer after polypectomy: Usefulness of endorectal US

PURPOSE: To determine the usefulness of endorectal ultrasonography (US) in staging rectal cancer discovered at polypectomy. MATERIALS AND METHODS: Before surgical resection, endorectal US was perform ed in 18 consecutive patients with adenocarcinoma discovered in polypectomy specimens. A rotating 7-10-MHz endoprobe with an inflatable balloon was us ed in all cases. The precise depth of penetration (T stage) was determined with endorectal US and correlated with the histopathologic findings. RESULTS: For detection of residual tumor after polypectomy, endorectal US h ad a sensitivity of 100%, specificity of 44%, positive predictive value of 64%, and negative predictive value of 100%. Although the precise T stage wa s correctly predicted with endorectal US in only eight patients (44%), endo rectal US was able to demonstrate whether the tumor was limited to the bowe l wall in 16 patients (89%). CONCLUSION: Endorectal US is an accurate technique for localizing tumors to or beyond the rectal wall in patients who have undergone diagnostic polype ctomy. Although inaccuracies in determining the specific T stage may occur, endorectal US facilitates surgical planning in the vast majority of patien ts and should therefore remain the local staging technique of choice in thi s specific patient population.