6 weeks for having a cyst removed from testicle? Wow, seems like an extended time.
If your doctor says you need surgery and you must be off for 6 weeks then all you will need to do is tell your employer that per your doctor / surgeron you will need x amount of time off to heal.
Of course they will need a doctors excuse to be submitted to them. However what type of surgery you have is your business.
They may ask is it necessary or selective.
There is no law that I am aware of that states that they must know what you are having done.
It is a private matter...you business is just that, private.