Evaluation of polyps by endoscopic ultrasonography (EUS): implication for endotherapy

EUS is the single best imaging modality in precise visualization of the five layers structure of G.I. tract wall, space occupying lesion and surrounding structures. In case of "protruding lesioy;' into the G.I. lumen, the site of origin of the tumor can be easily determined by EUS, and then its nature can be presumed (1). However, despite of these tiny details of the G.I. wall obtained by EUS, histology is still mandatoiry,especially when dealing with lesion suspected of malignancy (2). In case of sessile malignant "polypoid" lesion, Endoscopic Mucosal Resection (EMR) guided by EUS, could be considered in specific cases of selected patients. Conventional EUS transducer (7.5 and 12 Mhz) employed for this purpose is not sufficient for differentiating cancers invading the muscularis mucosae from those invading the sub-mucosa. A Miniature Ultrasonic Probe (20 and 30 Mhz) which can be used through the biopsy channel of an endoscope has recently been developed and is accurate in measuring such a superficial infiltration and in assessing regional lymph nodes allowing then an exact pre-treatment staging. In patient not fitted for surgery, with a lesion less than 2 cm and involving less than half circumference of the lumen, EMR could be performed according to the parietal infiltration (T), the nodal involment (N) and the related involved organs (Esophagus, Stomach, Colo-rectum). Conclusions: EUS may be usefull and sometimes is mandatory for assessing the GJ. tract polyps before resection.