Hi Barb
Thanks for your question! Cathy and I briefly discussed it - would it be possible to clarify the context to see if we understood the question correctly? We are assuming that the context of the question would be from a documentation standpoint, but please correct me if I'm wrong. If that's the case, would the question be more like: 
- "When describing/documenting a wound(s), when can one consider multiple wounds that are close to one another a single wound (i.e., a "clustered wound")?" 
OR would the question be from a clinical standpoint, like:
- "If multiple lesions are clustered/close to one another, how can one predict they will coalesce/merge and become a single wound?"
OR would it be more like something else?

My questions is "When describing/documenting a wound(s), when can one consider multiple wounds that are close to one another a single wound (i.e., a "clustered wound")?" As I mentioned above, at one point I was told that if the wounds are located 1cm or less from each other in a specific area and are at the same depth or tissue level, they can be considered 1 wound and listed as a "cluster". Is this how you would look at this and are you aware of any resources that actually set parameters as to when multiple wounds in the same area can be considered as one?

Hi Barb

Thanks for the explanation. Six wound care specialists compared notes regarding your question (Cathy, Kathy, Samantha, Tiffany, a colleague who worked as a medical director at a wound measurement app company, and I). Below is a compilation of our initial thoughts.

- Grouping multiple wounds that are close to one another and documenting them as a single wound ("clustered wound") could simplify assessment, when appropriate. We will keep on searching, but so far haven't come across a specific set of criteria that defines when multiple wounds that are close to one another can be considered 1 wound and listed as a "cluster". However, we've been able to gather relevant information that can be used as a proxy when crafting internal policies/guidance for a wound care program:

- For any chronic wounds as long as the wounds have the same etiology:
> If 2 wounds merge, they can be documented as a single wound [1]
> If wounds don't merge but are in close proximity: good interrater reliability regarding 'how far apart' lesions are should be in order when deciding whether to group versus or not

- For pressure ulcers/injuries (PU/PI):
> Usually, PU/PI don't present as "clusters" like other ulcers such as venous ulcers. However, many other types of skin lesions of different etiology (i.e. not related to pressure/ shear) may develop near a PU/PI, such as skin tears or maceration from friction/moisture. Even if those lesions appear in close proximity to the PU/PI, those wouldn't be clustered with the original PU/PI, as they have a different etiology [2]
> When a single skin damage is caused by MASD and PU/PI (i.e., MASD and PU/PI merge), it can be reported as a PU/PI [3]
> If a medical device related PU/PI is in close proximity with another PU/PI that occurred due to pressure/shear over a bony prominence, those should not be grouped/clustered. Those are counted separately for incidence and prevalence [4]
> When deciding when to "group" ulcers and document as one ulcer, one might want to keep in mind that to be eligible for certain support surfaces, a larger ulcer or multiple stage 3 or 4 ulcers are part of the requirements. [5]

- For chronic wounds that are not PU/PI (e.g. VLU):
> At times, VLUs have multiple wounds close to each other. In those cases, many wound clinicians (and even wound certification courses) would suggest grouping the wounds that are present in a specific anatomical location (e.g. gaiter area), as long as they have the same etiology. The 'clustered wound' would count as one wound. The area in which the cluster is located should be measured and delineated in photos. The largest wound within the cluster is also measured, and the other ones would be considered satellite wounds. Wound bed appearance and other characteristics would be documented as well. Smaller wounds tend to change their appearance often and it is often not easy to document/measure all of them. Digital wound measurement/documentation apps also recommend the same approach (that is, when multiple wounds are close to one another in one anatomical area, those can be 'clustered')
> One idea could be to consider satellite wounds that are present in the peri wound of a larger ulcer as being part of the cluster. Periwound is defined as the area <4 cm around the main wound (Bates-Jenssen wound assessment tool ).[6] Satellite wounds are wounds located in the periwound [7]

[1] Canadian BC Provincial Nursing Skin & Wound Committee
[2] https://www.ahrq.gov/patient-safety/settings/hospital/resource/pressureulcer/tool/put5.html
[3] https://www.nursingtimes.net/clinical-archive/tissue-viability/new-guidance-on-how-to-define-and-measure-pressure-ulcers-10-09-2018/
[4] https://www.ahrq.gov/sites/default/files/wysiwyg/professionals/systems/hospital/pressure_ulcer_prevention/webinars/webinar6_pu_woundassesst.pdf
[5] https://woundreference.com/app/topic?id=pressure_ulcer_injury_treatment&find=support+surface#pressure-redistribution-
[6] https://wwwoundcare.ca/Uploads/ContentDocuments/BWAT.pdf
[7] https://www.woundinfection-institute.com/wp-content/uploads/2017/03/IWII-Wound-infection-in-clinical-practice.pdf