A fit 46-year-old woman has had right upper quadrant pain for two days. Temperature is 38.1 °C, WCC 14 × 10⁹/L and CRP 120 mg/L, with normal liver function tests. Ultrasound shows a thick-walled gallbladder containing stones, pericholecystic fluid and a 4 mm common bile duct.
Which plan is most appropriate?