Tia, 13, from Swansea, was among a group who trailed the new technology, which allows them to upload pictures to monitor their ulcers.
Other features include a countdown timer to remind patients when they need to move to relieve pressure.
The app was developed with Welsh Government funding.
It was created by Abertawe Bro Morgannwg health board's Pressure Ulcer Prevention and Intervention Service and, following the trial, more work is to be carried out to improve it.
It is hoped it will eventually be available to people at home who have pressure ulcers or are at risk of developing them, along with the nurses caring for them.
Pressure ulcers are caused when an area of skin is placed under pressure, often if someone is lying or sitting for prolonged periods.
Tia uses a wheelchair and her mother, Elaine Saddington, said it was useful to take pictures of her daughter's pressure areas to ensure an ulcer did not develop.
She explained that the pictures are uploaded automatically to the app and they can then be seen by staff at Swansea's Morriston Hospital which "eliminates the need for as many appointments".
"They can see how the pressure ulcer is progressing on a daily basis. If we have any concerns we can call them and they will give advice, again without us having to make an appointment."
A schoolgirl with spina bifida has helped test a new app that could improve the way nurses treat patients with pressure ulcers.