Prostate biopsy is a procedure in which small hollow needle-core samples are removed from a man's prostate gland to be examined for the presence of prostate cancer. It is typically performed when the result from a PSA blood test is high. It may also be considered advisable after a digital rectal exam (DRE) finds possible abnormality. PSA screening is controversial as PSA may become elevated due to non-cancerous conditions such as benign prostatic hyperplasia (BPH), by infection, or by manipulation of the prostate during surgery or catheterization. Additionally many prostate cancers detected by screening develop so slowly that they would not cause problems during a man's lifetime, making the complications due to treatment unnecessary.