How can I be sure if I am experiencing testicular atrophy? Is the only way through an ultra sound? How would I know if a varicocele is causing it?

By history & exam... Detailed history stressing sequence of events and direct palpation are the essential steps to suspect and even confirm testicular atrophy. If necessary, scrotal US can help but not essential. How to have the steps of care done correctly? Follow instructions described in http://formefirst.com/eNewsletter06.html; then you can work closer & better with doc so to reach right diagnosis for right care.