Background Endoscopic ultrasonography, both conventional and interventional, has been used increasingly during the past 20 years and is deemed a safe technique. Its complication rate, however, has been studied to only a limited extent. This multicentre investigation sought to establish the complication rate for a large number of endoscopic ultrasonography procedures. Methods By means of a questionnaire, we collected data from six centres on the number of endoscopic ultrasonography examinations performed and divided them into conventional and interventional examinations of the upper and lower gastrointestinal tract. Information was obtained on technical modalities such as instruments and sedation and, for interventional endoscopic ultrasonography, indications, pre-procedural exams and technical details (needle calibre, number of passes) had to be specified. Complications were classified as mild, moderate, severe or fatal and their onset as immediate, early or late. Variables that entered into the analysis of complication rate included type of endoscopic ultrasonography instrument used, type and site of lesion biopsied, number of needle passes and operator experience. Results Eleven thousand five hundred thirty nine endoscopic ultrasonographic procedures were reported, of which 10,731 were conventional and 808 interventional. No deaths occurred; there were 14 (0.12%) complications, 5 (0.046%) of them following conventional endoscopic ultrasonography and 9 (1.11%) after interventional endoscopic ultrasonography. Seven complications were mild, four moderate and three severe. Conclusions Both conventional and interventional endoscopic ultrasonography were confirmed to be acceptably safe techniques.
