>>938055257She could have the Bombay blood type. Around one in 250,000 people have that. It's more common in India and in inbred people.
It's more likely she got pregnant and only had her Rh type tested, for the purpose of administering Rhogam.
As a medical technologist I find this annoying when doctors order an Rh instead of an ABO/Rh. It isn't much faster and the computer gets all upset later on if the patient is typed again because when I enter the full blood type it thinks there is a conflict with previous results.
But then nurses get all confused because if a patient is A positive or whatever then they don't know what the patient's Rh type is. I've met nurses who think the Rh type is whether or not the patient is HIV positive. No, we don't keep a fridge full of HIV positive blood around.