David was born with cryptorchidism, but only one of his testes is affected. His non-descending testis was not surgically corrected. Is David sterile or will he still be able to have children? In the...

David was born with cryptorchidism, but only one of his testes is affected. His non-descending testis was not surgically corrected. Is David sterile or will he still be able to have children?

In the initial period after vasectomy, men are advised to use another method of contraception to avoid unintended pregnancies. Why is this necessary?