Talk Before You Retrieve: Agent-Led Discussions for Better RAG in Medical QA

Medical question answering (QA) is a reasoning-intensive task that remains challenging for large language models (LLMs) due to hallucinations and outdated domain knowledge. Retrieval-Augmented Generation (RAG) provides a promising post-training solution by leveraging external knowledge. However, existing medical RAG systems suffer from two key limitations: $\textbf{(1)}$ a lack of modeling for human-like reasoning behaviors during information retrieval, and $\textbf{(2)}$ reliance on suboptimal medical corpora, which often results in the retrieval of irrelevant or noisy snippets. To overcome these challenges, we propose $\textit{Discuss-RAG}$, a plug-and-play module designed to enhance the medical QA RAG system through collaborative agent-based reasoning. Our method introduces a summarizer agent that orchestrates a team of medical experts to emulate multi-turn brainstorming, thereby improving the relevance of retrieved content. Additionally, a decision-making agent evaluates the retrieved snippets before their final integration. Experimental results on four benchmark medical QA datasets show that $\textit{Discuss-RAG}$ consistently outperforms MedRAG, especially significantly improving answer accuracy by up to 16.67\% on BioASQ and 12.20\% on PubMedQA. All code and prompt materials will be made publicly available.