Flexible endoscopic ultrasonography of colonic tumors: indications and results

Based on the positive results of endorectal ultrasound we evaluated flexible colonic endosonography for colonic tumors. At present there are no generally accepted indications for this procedure. Moreover, it is unclear whether the results are valid enough to warrant specific therapeutic interventions.

Over a one-year period we performed flexible colonic endosonography (12 MHz rotating scanner) on 31 patients with colonic tumors. The examination was only performed when therapeutic implications were expected (e.g. endoscopic procedure when there was no sign of malignancy; oncological resection when there were signs of malignancy in ulcerative colitis or familial polyposis).

Of 40 tumors examined, 36 were correctly staged by endosonography, compared to postoperative histology as the gold standard (16 of 17 adenomas, 5 of 5 pT1 carcinomas, 8 of 8 pT3 carcinomas). In two cases pT4 carcinomas were wrongly classified endosonographically as uT3 carcinomas, because the infiltration of the visceral peritoneum was technically not recognizable. Overall the accuracy rate of staging was 85%. Lymph node staging was correct in 36 of 40 patients, amounting to an accuracy rate of 90%.

Because of its high accuracy rate flexible colonic endosonography has a place in the preoperative staging of colonic tumors in selected patients, especially those with ulcerative colitis, familial adenomatous polyposis or macroscopically suspicious adenomas. It helps to clarify the extent (oncological resection, lymphadenectomy) of resection required in conventional surgery and helps to avoid laparoscopic procedures in advanced colonic cancer.