Varicocele is a swelling in the veins above the testicles. It is similar to having varicose veins in the legs. The swelling occurs when too much blood collects in the veins. Varicocele most often occurs around the left testicle. When blood collects in the veins above the testicles, changes occur that can reduce the number and the quality of the sperm. More than half of men who have varicocele have a reduced sperm count. In many cases, sperm count improves after treatment. Your doctor may recommend surgery to tie off the enlarged veins around the testicles to improve male fertility.