What clinical finding would support a diagnosis of testicular torsion rather than epididymitis?

A negative Prehn's sign is a strong clinical finding that supports a diagnosis of testicular torsion over epididymitis. The Prehn's sign is a physical exam maneuver where lifting the affected testis provides relief of pain in cases of epididymitis, indicating inflammation. In contrast, testicular torsion, which involves the twisting of the spermatic cord, does not typically relieve pain with elevation; thus, a negative Prehn's sign is consistent with torsion.

Additionally, the presence of the cremasteric reflex, which is the contraction of the cremaster muscle and elevation of the testis in response to stroking the inner thigh, is usually intact in cases of epididymitis but can be absent in testicular torsion. Normal Doppler ultrasound findings would not support either diagnosis directly, but would be more suggestive of other conditions. Therefore, the negative Prehn's sign is a critical differentiating factor in this clinical scenario, leading to a more accurate diagnosis of testicular torsion.