During the ERCP procedure, the choice of drain placement is based on the patient’s condition. For patients with multiple stones in the common bile duct and incomplete stone extraction, a nasobiliary drain is placed and the time of extraction is decided according to the different conditions of the patient. For patients with common bile duct stones, if the stones are relatively clean, an imaging will be performed after 2-3 days of observation. If there are no stones left, the nasobiliary duct can be removed. For patients with recurrent disease and relatively more stones, ERCP may have to be performed again to check or remove the stones, which will prolong the time of placing the nasobiliary tube accordingly.