Pediatric USG — Testicular Torsion No Flow

A 14-year-old boy presents to the emergency department with sudden-onset severe left scrotal pain that woke him from sleep. On examination, the left testis is high-riding with a horizontal lie, and the cremasteric reflex is absent. Scrotal ultrasound with color Doppler is performed. The structure marked **B** in the diagram shows absent intratesticular flow in the left testis, while the right testis demonstrates preserved flow. What is the most critical next step in management?