I hope this helps - A Critical Look at Rhogam and Rhesus Disease
RhoGAM? - Page 2
I think there are two rhogam tests the basic titer one and a more extensive one. People can test negative but just be barely positive. If you are very concerned about getting the shot then ask for the more extensive test. It might be you who is barely positive and you won't need a shot at all.
What is the medical term for the basic titer test and the more extensive one?
Also, when you mentioned if it comes back as barley positive, you might not need the shot at all. Why wouldn't you need the shot at all? Do you have any research, or links you could suggest, so I can read more on this as I am very interested.