What does the CA 19 test specifically test for?

My sincere sympathy for all people suffering. My son is now going through this. The pain is bad enough but not being able to find the source doubles the stress and is so de-moralizing.

He did have one success previously...a major hospital never diagnosed an infected gall bladder for two years. He wound up in a small hospital ER one night and a surgeon there pinpointed the problem almost immediately and removed his severely infected gall bladder. So sometimes, you get lucky and find that one doctor who is a great diagnostician and has had experience dealing with an issue.