It isn't too bad....yes you can feel sick from it, esp if you have stones. I just had one last month. You go in, they put an IV in, inject the isotope and wait for it to go thru the liver, etc to the gallbladder. Once it reaches the gallbladder (about an hour to an hour and half) they will hook up a medication that will make the gallbladder contract like you just ate a big meal. I had some pain, esp in my back but didnt' feel sick. They wait to see how long it takes the isotope to leave the gallbladder. If your DH doesn't have stones, he may have a dyskinesic GB, which means that it just doesn't work. That is what I had. So, you can get pain with or without stones. They look at how long it takes the isotope to leave, usually below 30% function is abnormal. Mines was at about 18-20%. I was just sick feeling all the time, bloated after eating, just uncomfortable with pain sometimes, not all the time.
You are just a bit radioactive after lol, if you have to travel by plane within the next 72 hours they give you a yellow card to say why you set off the detector lol Other than that, it isn't anything but drink a lot of water and wash your hands after peeing.
Oh, and he might be sick for a day or so after the HIDA scan when he eats. They didn't tell me that, I actually felt WORSE after the scan. I had my GB out within a month and fell 100% better. Have some GI issues that are common after, but it is sooo much better!
Good luck! Oh, did he have an ultrasound...that usually picks up stones unless they are in the ducts. I didn't have any stones, but with my symptoms the surgeon had an inkling that my GB wasn't working right.