A diagnosis of gangrene is based on a combination of physical examination, medical history and tests.

Your doctor will want to find out whether you have any long-term health conditions, or if you've recently experienced any injuries that could have caused the condition.

They'll also examine the affected area to check for any obvious signs of gangrene, such as a foul odour or discolouration of the skin.

A number of tests and investigations can be carried out to confirm the diagnosis of gangrene. These include:

• blood tests to check for an infection
• fluid or tissue culture – where a small tissue or fluid sample from the affected area is tested to find out which bacteria are responsible for the condition and determine the most effective antibiotic to treat it with
• blood cultures – where a sample of blood is taken and put into special culture bottles and placed in a warm environment (incubated) to encourage the growth of bacteria so they can be examined further
• imaging tests – a range of imaging tests, such as X-rays, magnetic resonance imaging (MRI) scans or computerised tomography (CT) scans can be used to confirm the presence and spread of gangrene; these tests can also be used to study blood vessels so any blockages can be identified
• surgery – a surgical examination under anaesthetic may be necessary to confirm a diagnosis of gangrene deeper inside the body

As gangrene is a potentially serious condition, treatment is usually started before the results of any tests become available.