I have heard it suggested (secondhand, not from a doctor) as a means of helping overcome infertility, which would imply to me that it doesn't have too much in the way of consequences, anyway.

Urine is acidic which would tend to upset the balance in the vagina, probably no worse than a douche, though. Remember, unless the man has an infection, urine is sterile. (With the obvious qualifier that peeing in her is *NOT* safe sex!)