It is possible to perform surgery for an undescended testicle in a sixteen year old. I am puzzled by the fact that such treatment has not been offered to you when it was diagnosed. I wonder if you have true undescended testicle or could it be a retractile testicle. A retractile testicle as the name suggests can be retracted up out of the scrotum and into the inguinal canal and it can then pop down again. When the testicle retracts the scrotum will appear empty on that side thus creating the appearance of an undescended testicle. If you have true undescended testicle then you should have it repaired because failure to repair it can eventually result in inability to produce sperm from that testicle. There is also an increased risk of malignancy in a non-repaired undescended testicle. This risk arises in later life and is not a risk for you now at sixteen years of age. You should have this condition repaired.