How do if i know if blood isn't flow to my testicles correctly?

Testicular Torsion: No blood flow to the testicle occurs when the stalk that goes to the testicle twists, blocking the blood vessels within. The blood flow is reduced or absent, resulting in severe pain, elevation of the testicle in the scrotum and often nausea or vomiting. If you suspect this is occurring at any time, this is an emergency. If not fixed with 6-8 hours, testicle death and loss is common.