Adding the clinical framing, because it changes how the question reads.
Gallbladder ultrasound monitoring on gallbladder risk: given the known gallstone risk with rapid weight loss, my doctor orders gallbladder ultrasound every 6 months:
Baseline: normal, no stones or sludge
Month 6: small amount of biliary sludge, no stones
Month 12: sludge resolved, gallbladder normal
Ursodeoxycholic acid (Ursodiol) 300mg BID was prescribed prophylactically from the start. This reduces gallstone formation during rapid weight loss by ~60% per the available data. Ask your doctor about prophylactic ursodiol if you're losing weight rapidly.