Fig. 1.

The techniques used for stone retrieval in the different difficulty grades. IA Transcystic blind basket trawling for a few distal CBD stones < 8 mm in diameter. IB Transcystic basket extraction of 1–10 stones 8–10 mm in diameter requiring further proximal cystic duct incisions. IIA Transcystic choledochoscopic stone extraction. IIB Transductal choledochoscopic stone extraction. IIIA Choledochoscopic exploration for 1–15 stones up to 15 mm in diameter; either transcystic for distal stones or transductal for CBD or intrahepatic stones. IIIB Transcystic choledochoscopic Wiper Blade Manoeuvre for intrahepatic stones of any number and any size. IV Choledochoscopic TCE for Mirizzi Type I or transductal exploration for impacted stones (any number or size) needing dislodging manoeuvres or antegrade stenting required. V Trans-fistula exploration for Mirizzi II or choledochotomy for impacted stones needing fragmentation/ open conversion / bilioenteric anastomosis e.g. Mirizzi III or IV