These days, vasectomies are generally covered in health insurance policies, as the procedure is not seen as a purely 'cosmetic' operation as a vasectomy can sometimes be needed and requested by a doctor for health reasons, and for this reason, most insurance companies cover it for their customers.
There is also another reason that Blue Shield Insurance most probably covers it - in general, a vasectomy is a straight forward, quick and safe procedure that is performed daily in hundreds of hospitals across the world. This is seen as a 'cheap' procedure and isn't very costly to the hospital, nor to the insurance company who foots the bill at the end of the operation, after you or the hospital has notified them.
However, insurance companies do vary somewhat, and there have been many times when people have 'assumed' something is covered and then become very unstuck when they are faced with a huge medical bill, and medical procedures certainly aren't cheap, as having a baby can cost around £30,000. It is always best to check with your insurance company, and in this case, I would contact Blue Shield Insurance and ask for confirmation. It may be worth writing to them, as this way, you'll receive the confirmation back in writing.
If not, why not dig out your insurance policy and refresh your mind on what is covered so that you know for sure that your vasectomy is covered and you won't be faced with a medical bill at the end of the operation.