An Undescended testis needs to be brought down because the longer it stays outside the scrotum (which is the ideal temperature for the testis to grow and function properly) ,the greater the likelihood of it losing its function .The changes that will affect the function of an undescended testis start as early as 6months of age. Surgery to bring an undescended testis down is best done from 6months to 2years.
A hernia may co-exist with an undescended testis. Both are repaired at the same Surgery.Bringing the testis down into the scrotum may improve future fertility (if done at the appropriate time) and places the testis in a position where it can easily be examined for any changes.Even if the testis was not brought down at the ideal , it can and should still be brought down. Even if the testis was not brought down at the ideal , it can and should still be brought down.A Paediatric Surgeon or Urologist may perform the surgery for these common surgical conditions in children.

The testis develops in the abdomen, somewhere near the kidneys, then follows a path to ‘travel” down into the scrotum as the child grows.
It may be located anywhere along its normal path of descent into the scrotum. Every newborn male should be duly examined after birth to check if the testes are in the scrotum.If a testis or testes (both) are not in the scrotum at birth , they may still descend later but if still undescended by age 1year,it is not likely to descend again.