Received: 18 August 2021
Accepted: 5 October 2021
First Online: 10 October 2021
: This study was performed following the Helsinki Declaration of the World Medical Association. Written informed consent was obtained from all the patients before conducting ERCP. Informed consent for study enrollment was obtained in the form of an opt-out on the website. This study protocol was approved by the Nara Medical University Ethics Committee (#1360).
: The authors declare no conflicts of interest for this article.