Operations classified for the present study

Cholecystectomy-related procedures (JKA20, JKA21 excluded)
Intraoperative cholangiography	TJK00, TJK01
Intraoperativ cholangioscopy	JKB20, TJK21
Common bile duct exploration	JKB00, JKB01
Laparoscopic transcystic stone removal	JKB11
Bilio-enteric anastomosis without resection	JKD
Endoscopic sphincterotomy	JKE02
Excision of bile duct	JKC
Reintervention on bile duct	JKF
Vessel suture	PCB, PCC
Bowel suture	JFA70, JFA71
Reoperations due to complications after previous abdominal surgery	JW
Other open procedures
Cholecystotomy	JKA00
Cholecystostomy	JKA10
Other operation on gallbladder	JKA96
Bile duct suture	JKB40
Other local operation on bile duct	JKB96
Transduodenal sphincterotomy	JKE00
Transduodenal sphincteroplasty	JKE06
Other transduodenal procedure on bile duct or sphincter	JKE96
Other operation on bile duct	JKW96
Incisional hernia repair	JAD
Other laparoscopic procedures
Laparoscopic cholecystostomy	JKA11
Other laparoscopic procedure on gallbladder	JKA97
Other laparoscopic local operation on bile duct	JKB97
Other laparoscopic operation on bile duct	JKW97
Other endoscopic procedures
Removal of common bile duct stones	JKE12
Lithotripsy	JKE15
Internal drainage	JKE18
Removal of foreign body (stent)	JKE22
External drainage	JKE25
Dilatation of bile duct	JKE32
Other endoscopic procedure	JKE98, JKW98
Percutaneous procedures
Cholecystostomy	JKA13
Transhepatic drainage	JKB30