The key is to check each testicle, one at a time, using both hands by “firmly, but gently, rolling the testicle between the thumb and fingers”.
Feel for any lumps, tender spots, hardness, swelling or a feeling of heaviness.
Do note the sperm cord, known as the epididymis, can be “rather tender” to touch.
If you’re concerned about anything you feel in that area, then do book an appointment with your GP.
When the GP discusses your concerns with you, they may perform a transillumination.