Will orchitis cause sterility?

Very rarely. There is not much published information on the exact percentage of patients with fertility problems after orchitis, but orchitis of only one testicle should not decrease fertility as long as the other testicle is normal. After orchitis of both testes, some reports say about 10% of men will have decreased fertility, and very rarely will a man become sterile.
Orchitis. If it is bilateral, like in mumps, it can cause infertility.. If unilateral and other testicle is normal there is a good chance that you may still be fertile..