There are no specific causes of testicular torsion.
The testicles develop inside the belly and drop down into the scrotum around the sixth month of pregnancy. Once the testicle drops into the scrotum, it attaches to the inside. When a testicle does not drop down into the scrotum (undescended testicle), it does not attach correctly, which causes a higher risk of twisting.
When the cord twists, it blocks the blood leaving the testicle, which causes swelling and pain. This can lead to permanent damage to the testicle. Once testicular torsion has occurred on one side, there is a higher chance it can occur on the other side. This can happen anywhere from a few weeks to months later.