Cross-over: in the ESWL group, if no elimination of the fragments is observed one week after the last ESWL, endoscopic drainage of the main pancreatic duct will be carried out at this time in case of continuous pain. For patients without continuous pain, delayed spontaneous elimination of the fragments will be sought by CT Scan and S-MRCP 2 months after the last ESWL. Endoscopic drainage of the main pancreatic duct will be proposed during follow-up only to the patients presenting a painful attack of CP.