面对医生的确认类提问，患者进行扩展回答是医患交流中一种较为常见的现象。尽管扩展回答在交流层面违背提问对回答的结构限定，而且还占用更多的交流时间，但患者的扩展回答并不是一种消极的交流现象。本文采用会话分析的研究方法，以发生在泌尿外科门诊的医患交流为语料，探究患者扩展回答的具体原因及序列语境，分析扩展回答的价值和意义。通过语料分析，我们发现患者扩展回答的内容均有一定的医学价值，医生在诊疗过程中应该给予患者构建扩展回答的时间和权利，这样做不仅有利于医生开展有效诊疗，还有利于和谐医患关系的建设。

The Patient’ s providing an extended answer to the doctor’ s yes / no interrogative is frequently observed in medical interaction. Though an extended answer violates the grammatical constraint from a yes / no interrogative, and takes more time in clinical interaction , the patient’ s extended answers are not always negative. This paper, adopting conversation analysis as its research methodology and taking naturally occurring doctor-patient interaction at urology department as its data, probes into the sequential environments and reasons for the patient’ s extended answer construction, furthermore, the value and function of extended answers has also been summarized. Data analyses support that the doctor could permit the patient to take more time to construct extended answers in clinical interaction, because the information in extended answers might have certain medical value. The doctor’s permitting the patient to construct extended answers not only help the doctor to carry out effective diagnosis and treatment, but also to build harmonious doctor-patient relationship.