cs.CVMar 12, 2026

Surg-R1: A Hierarchical Reasoning Foundation Model for Scalable and Interpretable Surgical Decision Support with Multi-Center Clinical Validation

Authors: Jian Jiang, Chenxi Lin, Yiming Gu, Zengyi Qin, Zhitao Zeng, Kun Yuan, Yonghao Long, Xiang Xia, +19 more

Organizations: Global College, Shanghai Jiao Tong University, Shanghai, China · Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, USA · Department of Biomedical Engineering and Department of Electrical and Computer Engineering, National University of Singapore, Singapore · ICube, University of Strasbourg, CNRS, IHU Strasbourg, France · Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China · Department of Gastrointestinal Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China · College of Electronic and Information Engineering, Tongji University, Shanghai, China · Chengdu Withai Innovations Technology Company, Chengdu, China · Division of Pancreatic Surgery, Department of General Surgery, West China Hospital of Sichuan University, Chengdu, China · Department of Surgery, The Chinese University of Hong Kong, Hong Kong SAR, China · Nvidia, US · Massachusetts General Hospital, Massachusetts, US · Department of Surgery, Duke University, Durham, NC 27707, USA · School of Automation and Intelligent Sensing, Shanghai Jiao Tong University

Abstract

Surgical scene understanding demands not only accurate predictions but also interpretable reasoning that surgeons can verify against clinical expertise. However, existing surgical vision-language models generate predictions without reasoning chains, and general-purpose reasoning models fail on compositional surgical tasks without domain-specific knowledge. We present Surg-R1, a surgical Vision-Language Model that addresses this gap through hierarchical reasoning trained via a four-stage pipeline. Our approach introduces three key contributions: (1) a three-level reasoning hierarchy decomposing surgical interpretation into perceptual grounding, relational understanding, and contextual reasoning; (2) the largest surgical chain-of-thought dataset with 320,000 reasoning pairs; and (3) a four-stage training pipeline progressing from supervised fine-tuning to group relative policy optimization and iterative self-improvement. Evaluation on SurgBench, comprising six public benchmarks and six multi-center external validation datasets from five institutions, demonstrates that Surg-R1 achieves the highest Arena Score (64.9%) on public benchmarks versus Gemini 3.0 Pro (46.1%) and GPT-5.1 (37.9%), outperforming both proprietary reasoning models and specialized surgical VLMs on the majority of tasks spanning instrument localization, triplet recognition, phase recognition, action recognition, and critical view of safety assessment, with a 15.2 percentage point improvement over the strongest surgical baseline on external validation.

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