Gallbladder sludge, typically an incidental finding on ultrasonography or other imaging, can either spontaneously resolve, wax and wane, or progress to formation of gallstones [1].
You can freeze your fat cells safely. The short answer is yes, but to get comparable results, it takes careful treatment planning, a skilled practitioner and multiple treatment cycles.ryolipolysis (fat freezing), marketed as CoolSculpting, is a treatment that originated after researchers fully understood what happens when humans get frostbite: fat cells freeze before skin freezes.
Fat can go rancid, even while frozen (though it does take much longer, I suspect this is part of what @ElendilTheTall was referring to as properly bad.) The higher the fat content the faster it can go bad. If after thawing you are not confident of its safety then yes, throw it out.