Endoscopic ultrasonography (EUS) is an essential technique required in diagnosis of pancreatobiliary diseases. In previous studies, 6% of patients who undergone EUS had significant throat pain. (NRS scale 5 or greater) Although some endoscopists think balloon inflation while EUS insertion could result in decreased throat damage and pain, there is no data to back up. We designed a single center randomized pilot study to compare throat pain caused by EUS insertion with conventional vs balloon inflation method.

All patients who are undergoing EUS with radial type echoendoscope will be asked for an informed consent. Subjects will be randomized to conventional insertion arm and balloon inflated insertion arm. All patients will be sedated according to SNUH endoscopy center protocol. Conventional insertion will be done in conventional insertion group, and balloon inflation before the start of procedure will be done in balloon inflated insertion arm. After the EUS procedure is finished, subject will be moved to a recovery room. As soon as the subject is recovered from sedation, throat pain will be assessed in NRS scale and be recoreded. Information of insertion failure and balloon damage during insertion will be also collected.

Inclusion Criteria:

• Patients aged from 20 to 80
• Patients undergoing EUS with radial echoendoscope

Exclusion Criteria:

• Refuse to participate the study
• Refuse EUS procedure