They have phone apps for everything these days…
I’ve spotted a new app (for andriods or iphones) produced by a lymphoedema specialist physio
https://itunes.apple.com/au/app/lymphoedema-breast-cancer/id568232231?mt=8
I’ve just bought the Android version (cost £1.30) and it gives general advice on lymphoedema prevention similar to what you get anywhere, so that part is not worth £1.30
However what is useful about this app is that you can measure your arm circumference in 5 different places and it calculates the volume and gives you the percentage difference between arms. If you repeat the measurements over time, you can see if the difference is changing which might be an early sign of lyphoedema.
If it is not changing signficantly this can be reassuring to worry warts like me.
There is a useful video that shows you how to do the measurements:
youtube.com/watch?v=MQER6cuqHHw
I just measured my arms and the difference between the two was -5% (ie my bad arm was 5% smaller than my good arm). My bad arm is my non-dominant arm so it is supposed to be a bit smaller than my good arm, so I’m assuming that -5% is around normal, but will continue to monitor.
Usual caveats about the app not intended for self-diagnosis, so if you have symptoms, concerns etc etc see your nurse or docter