What is the definition or description of: torsion of testis?

Torsion: Torsion is the twisting of the blood vessels supplying the testicle to the point where no blood flow is present. If it is not diagnosed or treated within 4-6 hours the testicle may not be salvaged.

Testicular torsion: Literally a twisting of the testis and the spermatic cord within the scrotal sac. Because the blood supply to and from the testis is contained in the twisted cord, this is a true surgical emergency.