A biopsy is a procedure in which small samples of the prostate are removed and then looked at under a microscope. A core needle biopsy is the main method used to diagnose prostate cancer. It is usually done by a urologist, a surgeon who treats cancers of the genital and urinary tract, which includes the prostate gland. Using TRUS to “see” the prostate gland, the doctor quickly inserts a thin, hollow needle through the wall of the rectum and into the prostate. When the needle is pulled out it removes a small cylinder (core) of prostate tissue. This is repeated several times. Most urologists will take about 12 core samples from different parts of the prostate.The biopsy itself takes about 10 minutes and is usually done in the doctor’s office. You will likely be given antibiotics to take before the biopsy and possibly for a day or 2 after to reduce the risk of infection. For a few days after the procedure, you may feel some soreness in the area and will probably notice blood in your urine. You may also have some light bleeding from your rectum, especially if you have hemorrhoids. Many men notice blood in their semen or have rust colored semen, which can last for several weeks after the biopsy, depending on how often you ejaculate.Your biopsy samples will be sent to a lab, where they will be looked at a microscope to see if they contain cancer cells. If cancer is seen, it will also be assigned a grade (see the next section). Getting the results (in the form of a pathology report) usually takes at least 1 to 3 days, but it can sometimes take longer.Even when taking many samples, biopsies can still sometimes miss a cancer if none of the biopsy needles pass through it. This is known as a false-negative result. If your doctor still strongly suspects you have prostate cancer (because your PSA level is very high, for example) a repeat biopsy might be needed to help be sure about the results.