The term undescended testicle is used to describe any testicle not located in the scrotum, or not able to be brought into the scrotum. An undescended testicle is noted in approximately 2% of boys at the time of birth. In 50% of cases, the testicle will descend on its own into the scrotum by 6 months of age. In those patients in whom the testicle has not descended by 6 months of age, surgery will be required to place the testicle into the scrotum. Most testicles that are not in the scrotum can be felt, but in some circumstances the testicle can be located within the abdominal cavity and as a result be unable to be felt. In addition, a testicle may not be able to be felt simply because it never developed. Surgery for undescended testicles is recommended, as it is necessary for the testicle to be located in the scrotum in order to function properly. This seems to be largely due to the fact that the testicle needs to be 2-3 degrees cooler than the rest of the body. There has also been noted to be an increased incidence of testicular cancer in males with an undescended testicle, with tumors noted in approximately 2% of these patients. Placing the testicle into the scrotum may decrease the risk of cancer, but most importantly, it positions the testicle in a place where it can be easily examined. There is often concern regarding the effect of an undescended testicle on future fertility. Studies have demonstrated that in those males with one undescended testicle, fertility rates are equivalent to those of the general male population (85%).