Treatment strategy of chronic pancreatitis (CP) patients with large pancreatic radiolucent stone (≥ 5mm) has not been established. We aimed to figure out clinical features and efficacy of endotherapy for large pancreatic radiolucent stone.

1. Treatment strategy of CP patients with large pancreatic stone：

1. . For patients with large radiolucent stone，ERCP with balloon sphincteroplasty was performed directly to remove radiolucent stone. If ERCP intubation failed, endoscopic ultrasound-guided drainage of pancreatic duct, surgery or medication would be applied. ESWL was performed in the following situations. Frist, MPD strictures was so severe that dilation catheter can not be inserted during ERCP. Second, there was cystic dilatation in MPD and pancreatic radiolucent stone located in cystic dilatation could not be extracted by extraction balloon or basket. In the above cases, the naso-pancreatic catheterwas inserted during ERCP, and then ESWL would be performed with repeated injection of contrast medium. After ESWL, repeated washing and negative pressure drainage were performed, and at last contrast medium was injected again to make sure the stones were cleared. For patients without MPD strictures, the nasopancreatic catheter can be directly removed, otherwise the nasopancreatic duct would be cut off into a stent.
2. . For patients with large radiopaque stone, repeated P-ESWL sessions were performed, and ERCP was routinely performed 48 hours after the last P-ESWL. If ERCP intubation failed, medication or surgery would be recommended.

2. A prospective cohort study was conducted in CP patients with large radiolucent stone. Patients with large radiopaque stone were matched as the control group, with a ratio of 1:2 according to admission time.

3. The primary outcome was pain relief. The secondary outcomes were stone clearance, quality of life score, and changes in pancreatic exocrine and endocrine function.

Inclusion Criteria:

Clinical diagnosis of chronic pancreatitis; With pancreatic radiolucent stones large than 5mm

Exclusion Criteria:

Autoimmune pancreatitis; Groove pancreatitis; Pancreatic cancer diagnosed within 2 years after diagnosis of chronic pancreatitis

CP patients with pancreatic radiolucent stones large than 5mm from March 2011 to December 2018 admitted to Changhai Hospital were included in this study. Patients with pancreatic radiopaque stones large than 5mm were matched as the control group, with a ratio of 1:2 according to admission time. CP was diagnosed primarily based on the Asia-Pacific consensus. Pancreatic radiopaque stone was diagnosed by CT scan while radiolucent stone by MRI or MRCP.