Health histories vary from case to case according to their purpose.
The most complete is referred to as the 'comprehensive health history', and includes all of the elements described later in the chapter.
This type of history is the one most likely to give a picture of the whole patient, which is why a nurse assessment of a patients health history is incredibly important.
It is especially useful in situations such as:

• where reaching a diagnosis is difficult or complex
• where the patient has a range of different health problems
• prior to major treatment or surgery
• when a patient is newly enrolling with a healthcare provider, such as joining a new general practice.
  

It is regarded as the 'gold standard' in history taking, and is arguably under-used in many settings, often due to time constraints.
But a well-conducted comprehensive health history may well be invaluable in recognising a previously unidentified health problem or unmet need.
Getting straight to the point in your nursing assessment Other approaches to history taking are more selective.
In some situations, a selective approach, if performed safely, may be more appropriate.
This is often described as a 'focused health history', and most commonly involves the examiner asking selected questions directed by the presenting problem or need.
Examples of situations where this approach may be appropriate include:

• emergency situations, where it is necessary to gain a brief history and move on to rapid physical examination (with the likelihood of returning to a more comprehensive history later)
• minor illness or injury, where information relating directly to the presenting problem and its management may be all that is required
• pre-operative assessment, where the focus is on history relating to past surgery, and the respiratory and cardiovascular systems, in order to ensure safe anaesthesia
• follow-up or ongoing assessment, where the patient is well known to the examiner and thus the examiner builds their history taking on previously established information
• nutritional assessment
• mental health assessment

It takes a lot of practise to make wise judgements about what to ask and what not to ask, so if in doubt it is better to ask rather than not.
For example, if a patient has broken their arm, it may not seem relevant to explore all aspects of their family history or past medical history.
Yet some factors, such as a history of previous fractures or a family history of osteoporosis, would be relevant.
Guidance in the specific chapters, together with experience, will help you make these judgements.