A surgical instrument is a specially designed tool or device for performing specific actions of carrying out desired effects during a surgery or operation, such as modifying biological tissue, or to provide access or viewing it. Over time, many different kinds of surgical instruments and tools have been invented. Some surgical instruments are designed for general use in surgery, while others are designed for a specific procedure or surgery. Accordingly, the nomenclature of surgical instruments follows certain patterns, such as a description of the action it performs (for example, scalpel, hemostat), the name of its inventor(s) (for example, the Kocher forceps), or a compound scientific name related to the kind of surgery (for example, atracheotome is a tool used to perform a tracheotomy).

The expression surgical instrumentation is somewhat interchangeably used with surgical instruments, but its meaning in medical jargon is really the activity of providing assistance to a surgeon with the proper handling of surgical instruments during an operation, by a specialized professional, usually a nurse.

The medical history or anamnesis of a patient is information gained by a physician or other healthcare professional by asking specific questions, either of the patient or of other people who know the person and can give suitable information (in this case, it is sometimes called heteroanamnesis), with the aim of obtaining information useful in formulating a diagnosis and providing medical care to the patient. This kind of information is called the symptoms, in contrast with clinical signs, which are ascertained by direct examination. Most health encounters will result in some form of history being taken. Medical histories vary in their depth and focus. For example an ambulance paramedic would typically limit their history to important details such as name, history of presenting complaint, allergies etc. In contrast, a psychiatric history is frequently lengthy and in depth as many details about the patients life are relevant to formulating a management plan fora psychiatric illness.

The information obtained in this way, together with clinical examination, enables the physician to form a diagnosis and treatment plan. If a diagnosis cannot be made then a provisional diagnosis may be formulated, and other possibilities (the differential diagnosis) may be added, by convention listed in order of likelihood. The treatment plan may then include further investigations to try and clarify the diagnosis.