The evaluation of the patient's experience is becoming increasingly important as a better patient experience can improve the quality of the delivered health service. Patient-reported experience measures (PREMs) are self-reported assessment tools provided by patients about their experience during any health event. There are few PREMs's instruments in the field of gastrointestinal endoscopy, and none is specific for Endoscopic Ultrasound (EUS). The aim of this study is to develop a questionnaire to evaluate the experience of patients undergoing EUS, identifying and prioritizing the factors related to the patient's experience. In order of it, expected results are developing a valid tool of question to value patients experience during EUS and, for ranking, it is iphotized that will be more correlation with patients's and nurses's answer that clinicians's one. In literature is described that nurse's view and patient's view are more similar especially in those aspects concerning empatics and psychological aspects.

The study will consist of several phases: 1) Tool creation: a "patient reported measure of EUS" (PREUS) questionnaire will be created based on literature review; 2) Face and Content Validity: The PREUS tool will be submitted to 7 experts in the field (physicians, nurses, psychologist, communication expert, patients' advocacy representative) for a two-round evaluation and to "expert" patients who had already undergone EUS at least once. Content Validity Index (CVI) will be calculated and questions with a CVI < 0.70 will be excluded; 3) Questionnaire Creation: Based on the results of phase 2, a modified "PREUS" tool will be then evaluated by ranking the relevance of the identified questions in the previous phase (from 0 to 10) by 50 outpatients undergoing EUS and Cronbach's alpha will be calculated to determine reliability; 4) Ranking: tool of phase 3 will be also evaluated by 6 physicians and 13 nurses working in IRCCS Ospedale San Raffaele endoscopy Unit to measure the agreement between patients and health care professionals (HCPs) by the Spearman-Brown coefficients.

Inclusion Criteria:

• Age > 18 years;
• Outpatients undergoing EUS in I.R.C.C.S. San Raffaele Hospital (Milan, Lombardy, Italy);
• Written informed consent signed

Exclusion Criteria:

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Outpatients undergoing EUS in I.R.C.C.S. San Raffaele Hospital (Milan, Lombardy, Italy); HCP involved with EUS in I.R.C.C.S S. Raffaele Hospital (OSR).