This article mentions acute pancreatitis after blunt trauma causing fat embolus, but that's very different from gallbladder stones. That's the closest this article comes to a gallbladder problem. (That is, the pancreas is close to the gallbladder and can itself cause complications of pancreatitis, but there are many causes of pancreatitis).
http://emedicine.medscape.com/article/460524-overview
I do not believe gallstones can develop suddenly from any reason. I believe it takes time for stones to form and grow to a size that causes problems. However, you may have had gallstones for a long time and your gallbladder might be extremely inflamed, and if you are injured in the abdomen over your gallbladder, I would imagine that there would be a chance that the weakened wall of the gallbladder could be ruptured by that impact. But if that didn't happen and it's just a finding of gallstones, I agree it is just coincidental. Hey, my husband's appendix went bad less than a month after my gallbladder had to come out quite suddenly. There's another odd coincidence. Can't blame it on anything. Oh, and I never had an actual gallbladder attack until after my gallbladder ultrasound (just days later!). I don't blame the ultrasound for the gallbladder attack. I blame it on the fact that we had a party at work with both pizza and cheesecake. I wanted to go along with everybody and not make a fuss, even though I had not had an appetite for months and months. Knowing my gallbladder had stones, I tried to be sensible and just have two pieces of veggie pieces and two bites of cheesecake, you know, to be polite. The next day I had 30 hours of misery - my first gallbladder attack. If I hadn't just found out I had gallbladder stones, I might have thought it was a heart attack. It felt like I was having a heart attack, but lower.
I agree but does the amount of fat in the bloodstream increase when you are involved in an accident because of being knocked around thereby enhancing conditions developing gallstones?
Gallstones typically take awhile to form, so it's unlikely that the stones would be a result of a car wreck. It is more probable that she falls into the category of female at about 40 years of age and carrying some weight.