Which statement best differentiates acute testicular torsion from epididymitis on Doppler ultrasound?

Which statement best differentiates acute testicular torsion from epididymitis on Doppler ultrasound?

• A. Absent intratesticular blood flow in torsion
• B. Increased blood flow in torsion
• C. Decreased flow only in epididymis
• D. Normal flow in torsion

Answer: (A)

The key idea is how Doppler flow patterns reflect the underlying pathophysiology. Acute testicular torsion twists the spermatic cord and cuts off arterial inflow to the testis, so intratesticular blood flow drops markedly or becomes absent on color Doppler. Epididymitis, on the other hand, is an inflammatory process that causes vasodilation and hyperemia, so Doppler shows increased blood flow, often in the epididymis and sometimes the testis. Therefore, the best differentiator is absent intratesticular flow indicating torsion, whereas increased flow points toward epididymitis. In some late or partial torsion, flow may be reduced rather than completely absent, but absence is the strongest indicator of torsion.

The key idea is how Doppler flow patterns reflect the underlying pathophysiology. Acute testicular torsion twists the spermatic cord and cuts off arterial inflow to the testis, so intratesticular blood flow drops markedly or becomes absent on color Doppler. Epididymitis, on the other hand, is an inflammatory process that causes vasodilation and hyperemia, so Doppler shows increased blood flow, often in the epididymis and sometimes the testis. Therefore, the best differentiator is absent intratesticular flow indicating torsion, whereas increased flow points toward epididymitis. In some late or partial torsion, flow may be reduced rather than completely absent, but absence is the strongest indicator of torsion.