"Retained gallstones, also called dropped or slipped gallstones, are common during a laparoscopic cholecystectomy, with a reported incidence of 0.1–20%, and occur when gallstones are inadvertently spilt into the peritoneal cavity."
"T1: hyperintense"
"T1: hypointense"
"T2: hypointense"
"Many cases of dropped gallstones will be asymptomatic. However, patients may become symptomatic if a complication develops and may present with infective symptoms, pain or fistula (e.g. through the body wall) formation."
"The dropped stone will generally need to be removed if it is causing complications (e.g. abscess formation)."