A varicocele happens when the veins in the scrotum become enlarged. This leads to blood pooling in the veins instead of moving out of the scrotum.
Some varicoceles cause pain or discomfort, but many have no symptoms. However, it can lead to a shrunken testicle, low sperm count, and other problems that can cause infertility. In these cases, you may need surgery to remove the varicocele. If there are no symptoms or complications, you may not need treatment.
The exact cause of varicocele is unknown.