Domain-Guided YOLO26 with Composite BCE-Dice-Lov\'{a}sz Loss for Multi-Class Fetal Head Ultrasound Segmentation

ArXi:2603.26755v1 Announce Type: new Segmenting fetal head structures from prenatal ultrasound remains a practical bottleneck in obstetric imaging. The current state-of-the-art baseline, proposed alongside the published dataset, adapts the Segment Anything Model with per-class Dice and Lo\'{a}sz losses but still depends on bounding-box prompts at test time. We build a prompt-free pipeline on top of YOLO26-Seg that jointly detects and segments three structures, Brain, Cavum Septi Pellucidi (CSP), and Lateral Ventricles (LV), in a single forward pass.