What is a key clinical sign of testicular torsion?

The key clinical sign of testicular torsion is a negative cremasteric reflex. In normal physiological conditions, the cremasteric reflex is an involuntary contraction of the cremaster muscle, which draws the testicle up when the inner thigh is stroked. In cases of testicular torsion, this reflex is absent due to the compromised blood supply and nerve function resulting from the twisted spermatic cord. The absence of this reflex can help differentiate testicular torsion from other conditions such as epididymitis, where the reflex is typically present. Thus, a negative cremasteric reflex becomes a significant indicator for clinicians when diagnosing testicular torsion.