For what length of time does it take on average to get a diagnosis for a breast lump?

Up to a month: It can take up to a month to get a definitive diagnosis. First you need a good breast exam by a trained provider. Most breast lumps are benign, but if your doctor is concerned you may need imaging (mammogram, ultrasound, and/or mri) and possibly a biopsy. Then it takes 3-4 days for the biopsy results to come back. By the time all of these tests are done, it has taken a month.