Any factor that causes prostate damage or infection can raise PSA, such as urinary tract infection, prostate stones, recent catheterization and urethral cystoscopy, recent prostate puncture biopsy or prostate surgery. Sexual activity can increase PSA by 10%, and rectal examinations and prostate massage prior to blood PSA testing can also increase PSA values. Benign prostatic hyperplasia (BPH) can also increase PSA, mainly because more prostate cells produce more PSA. BPH produces a lower amount of elevated PSA than prostate cancer, so the PSA density (PSA value/prostate volume) is lower in BPH than in prostate cancer. The rate of change in PSA values over time is called the PSA rate. Most people believe that the PSA rate in prostate enlargement rarely exceeds 0.7 ng/ml.