In order to keep the quality of diagnostic EUS improving, as it is a dynamic process, the European Society for Gastrointestinal Endoscopy wants to set high standards and review their Impact. The aim of this multicenter study is to observe the impact that the publication and implementation of the ESGE guideline on quality improvement in 2017 had on the performance of endoscopists. We can furthermore establish a direct link to the new guidelines from November 2025 to find out whether the key performance measurements can be met.

This study is designed as a multicenter study involving three academic teaching hospitals (Warendorf (W), Ibbenbueren (I), and Trier (T)) and three university hospitals (Muenster (M), Kiel (K), and Oldenburg (O)) in Germany. The primary endpoint focuses on the frequency of obtaining a diagnostic tissue sample from EUS-FNA/FNB of solid lesions. The secondary endpoint is adequate endosonographic description of landmarks. As a further secondary endpoint in accordance with the ESGE updated Guidelines from 11/2025 we also included the signed informed consent before the examination. Until now we included 812 patients.

Three patient groups were formed:

• Before implementation of the guideline, before 2018 (retrospective, group I)

• After implementation of the guideline, from 10/2018 to 12/2023 (retrospective, group II)

• After implementation of the guideline, from 2024 on (prospective, group III)

For the calculation of the case number planning, it is assumed that the rate in group A is 78% and in groups B and C 88%.

The study was approved by the local Ethics Committee of University in Muenster and registered at ClinicalTrials.gov (NCT06727851).

Preliminary data has been collected in 4/6 hospitals (W, M, I, O) to date. Frequency rates of obtaining a diagnostic tissue sample:

•    77.6%, 91.7%, and 85% for W

•    92.5%, 84%, and 82% for M

•    84%, 80%, and 92.9% for I

•    83%, 85% and 85% for O

Adequate description of EUS landmarks

•    87.8%, 86.9%, and 90% for W

•    71.7%, 56%, and 68% for M

•    58%, 98%, and 100% for I

With regard to the corresponding explanations provided prior to EUS procedures, the mean values were 98.8%, 97.6%, and 94%. The data of the hospitals in Oldenburg and Kiel are under review and are expected to present for ESGE Days 2026.

In light of the most recent update to the guidelines, we can conclude that the aim of tissue sampling during EUS-FNA/FNB is met in three of four centers with a key performance measurement of more than 85%. The frequency of adequate description of landmarks in EUS improved in two of three centers following publication of the quality-improving ESGE guideline, reaching a KPM of 90%. A high degree of standardization using text building blocks may have been helpful in this regard. The slightly lower values for Center M could be explained by previous endosonographic examinations in other centers or the performance of CT scans. The rate of obtaining a diagnostic tissue sample improved in three of four centers. The informed consent was generally available. We assume that the slightly lower rates might be due to missed scanning of the documents.