Doctors and patients do not always understand each other. They may not speak the same language, the doctor may use terms and jargon which are unknown to the patient, the patient may have a vocabulary sufficient to describe the symptoms. Even when translation is provided, it is never foolproof, and cannot duplicate the trust established when the doctor and patient are able to confer directly.
The consequences of medical mis-communication can be severe. Patients become sicker because they do not understand how to follow the treatments prescribed, they pass on infectious diseases because they do not understand the nature of their illness, they do not understand the procedures for follow-up care. Doctors miss diagnoses, they prescribe treatment without explaining it adequately, they compensate for sketchy knowledge of the symptoms by ordering more tests, some expensive, others risky.