Word of warning...often, yellow bile vomit is indeed because the stomach is empty...or just irritated. Do not assume it has a connection to anal glands because that seemed to be the case with one posters dog...and, if anal glands are not self expressing as the dog poops, there will be more evidence than vomit (which I never heard of before being CAUSED by backed up anal glands alone)...the pooch will usually scoot on its rear due to the discomfort..and, there will often be a very unpleasent fishy odor eminating from...ahem...the base of the tale.

Last but not least, over expression of anal glands when not needed can eventually cause the glands to back up, as they will somewhat lose the natual ability to express themsleves on a natural and daily basis.

Diet is also another factor; a diet too heavy on soft food and/or people food or food that is just not the right food for your particular dog can also be the cause of anal gland back-up.
Proper feeding is often all that is needed for the problem to clear itself..with no further manual "expression" required...and improper or over feeding may even be the actual cause of the vomiting as well, with the anal gland issue being a secondary symptom of the improper diet.

Always check first with a vet before embarking on a routine expression of anal glands...as it better to find the cause of vomiting and the malfunctioning glands and rectify it if possible...then to assume that one must manually do the job that the glands SHOULD be doing on their own.

As for the vomit, almost all dogs will vomit on occasion...if it become frequent..especially as posted above, the dog should taken to the VET ASAP to be evalauted as a serios and (if left unchecked) possibly life threatening condition could be present.

Better safe than sorry.