The formation of a Mondors Cord may occur with or without breast augmentation. It is a blood clot or thromboses that occurs in a superficial breast vein or lymphatic vessel. It may feel uncomfortable, but resolves on its own this warm compresses. If you are a week or two out from your breast augmentation surgery taking Asprin or non-steroidal anti-inflammatory medications(Motrin, Advil, or othe brand name Ibuprofens) will speed the treatment process.
This is an extremely rare condition and should not steer you away from having your breast augmentation.
Thank you for your question and good luck with your surgery!