Hi Eva,
2 questions in one.
1."Will Breast Lift decrease the volume of a breast?" - Not really. A breast lift (mastopexy) removes some breast skin but mostly lifts the breasts making them perkier. It does not add volume and the only volume loss is the little excess skin removed by the procedure which rarely really affects breast size.
2. " had a lumpectomy 3 years ago, that breast sags now and the other one just a little" - If the breasts are otherwise equal in volume and only differ in the amount of sagging, the lifting would have to be different on one side than the other to TRY and approximate symmetric breasts. IF there is a volume difference between them as well, and you want them to be more symmetrical, the larger breast can be made a little smaller to try and match the smaller breast. All this can be done as part of the lifting procedure.
I hope this was helpful.
