Wound measurement should be a routine part of wound assessment as the size of a wound is regarded as one of the main indicators of progress or deterioration in wounds (although wounds may get bigger as debris is removed).
- Wound size is a key indicator of improvement or deterioration of a wound
- Determining surface area by multiplying length and width may prove inaccurate
- Tracing is a more difficult, but more accurate, wound measurement method
- Measuring most wounds on a weekly basis should be adequate
It is also seen as a way of evaluating the effectiveness of treatments (Langemo et al, 2008; Bryant et al, 2001). A seemingly simple task, it is however the subject of much debate and discussion. Wound measurement is important
In clinical practice the most frequently used methods of measurement are:
Determining length and width using a disposable ruler – these can be presented as length and width, and are sometimes multiplied to give a surface area;
Calculating the surface area using a tracing onto an acetate grid with predetermined size squares.
There are other, more sophisticated methods - such as the use of digital plainmetry - but these are not widely available in clinical practice.
Linear measurements with a ruler are perhaps the easiest to perform, but should not be used to calculate a surface area. Several studies have shown that as wounds are rarely a regular shape, this simple multiplication of length by width may overestimate the wound area by up to 70% (Langemo et al 2008; Moore, 2005).
Authors of these studies suggest that for a reliable measurement, length should be recorded as the longest measurement (in a head to toe direction) and width as the longest measurement at a 90o angle to the length. Where this does not seem appropriate the position of the measurements should be recorded either by using the clock face method, for example width measured from 2–7, or by making a simple drawing and indicating the position on the diagram.
Tracing wounds onto a custom-made acetate grid and counting the squares allows a more accurate surface area to be worked out. While this is a relatively simple exercise, it can be difficult to perform an accurate tracing as the acetate sheets sometimes steam up, making it difficult to see the wound edge. Large wounds are often bigger than the sheet and it can be hard to keep the sheet securely in place on circumferential wounds. In addition, individual clinicians may identify different wound edges – for example some may include areas of discolouration while others may only include the open area. Even they trace the same area they may count the squares differently.
The simplest way to improve consistency is by ensuring the method of counting is clear on the previous tracing, for example by using ticks to indicate full squares, and crosses or dots to show half squares. Tracing also allows clinicians to show percentages of other tissue types, such as the amount of slough or necrotic tissue, again by using some kind of key. This shows more subtle changes in the wound when its actual dimensions may not change, but it becomes cleaner.
Both these methods are simple to do and inexpensive. However, it is important they are carried out consistently if they are to produce useful clinical information. Whatever method is used it is essential to agree with local clinicians on what is being done and how.
For most wounds weekly measurement is adequate as it is unlikely that any significant change will be seen in a shorter period. Some wounds may only show changes over 2-4 weeks. It is important to consider the reason for measuring the wound when determining the frequency. For example, if it is to determine if a dressing offers a rapid way of debridement, it may be done more frequently than if it is just part of routine assessment of a chronic wound – in which case measurement may only be performed once a month.
Jacqui Fletcher is senior professional tutor, Department of Wound Healing, Cardiff
Bryant JL et al (2001) Reliability of wound measuring techniques in an outpatient wound centre. Ostomy and Wound Management; 47: 4, 44-51.
Langemo D et al (2008) Measuring wound length, width and area: Which technique? Advances in Skin and Wound Care; 21: 1, 42-45.
Moore K (2005) Using wound area measurement to predict and monitor response to treatment of chronic wounds. Journal of Wound Care; 14: 5, 229-232.