What is the role of scrotal ultrasound in the evaluation of acute scrotum and how does Doppler assessment help?

• A. Only measures testicular size
• B. Does not provide functional information
• C. Replaces surgical exploration
• D. Distinguishes testicular torsion vs epididymo-orchitis by measuring blood flow; absent flow suggests torsion; increased flow suggests infection

Answer: (D)

Assessing perfusion with Doppler is central to evaluating the acute scrotum. Scrotal ultrasound with Doppler combines structural imaging with real-time blood flow information, which is what helps you tell apart conditions that can look similar on exam. When torsion occurs, the blood supply to the testis is acutely compromised, so Doppler shows absent or markedly reduced intratesticular flow. In contrast, epididymo-orchitis causes inflammatory hyperemia, leading to increased blood flow to the testis and epididymis on Doppler. This contrast between low/absent flow and high flow is the key reason Doppler is so helpful.

Keep in mind that early or intermittent torsion can sometimes have preserved flow, so ultrasound findings should be integrated with the clinical picture. Ultrasound can also reveal other causes or clues, such as a whirlpool sign indicating a twisted cord, hydrocele, or edema patterns. Ultimately, Doppler-assisted ultrasound provides crucial functional information that guides urgent management, without delaying surgery when torsion is highly suspected.