If a doctor suspects that an enlarged prostate (benign prostatic hyperplasia, BPH), is causing a man’s troublesome urinary symptoms, a careful medical history, a physical examination, and laboratory tests are required to exclude conditions such as narrowing of the urethra (urethral stricture) and bladder disease. Some reports indicate that up to 30 percent of men who undergo surgery for BPH are found not to have prostate obstruction (meaning their symptoms were caused by something other than BPH). Men who experience moderate to severe symptoms may benefit from one or more of the following tests:
Uroflowmetry. In this noninvasive test, a man urinates into an electronic device that measures the speed of his urine flow. The average urine flow rate for a man over age 45 is 12 mL per second. A slow flow rate suggests a urethral obstruction. If the flow rate is high, a urethral obstruction is unlikely, and therapy for BPH will not be effective in most instances.
Pressure-flow urodynamic studies. These studies measure bladder pressure during urination by placing a recording device into the bladder and often into the rectum. The difference in pressure between the bladder and the rectum indicates the pressure generated when the bladder muscle contracts. A high pressure accompanied by a low urine flow rate indicates urethral obstruction. A low pressure with a low urine flow rate signals an abnormality in the bladder itself, such as one related to a neurological disorder. Such studies are necessary only in special situations where a diagnosis is unclear.
Imaging studies. In general, imaging studies are performed only in patients who have blood in their urine, a urinary tract infection, abnormal kidney function, previous urinary tract surgery, or a history of urinary tract stones.
Ultrasonography. This is the imaging study used most often in men with lower urinary tract symptoms. It involves pressing a microphone-sized device (transducer) onto the skin of the lower abdomen. As the device is passed over the area, it emits sound waves that reflect off the internal organs. The pattern of the reflected sound waves is used to create an image of each organ.
Ultrasonography can be used to detect structural abnormalities in the kidneys or bladder, determine the amount of residual urine in the bladder, detect the presence of bladder stones, and estimate the size of the prostate.
Cystoscopy. In this procedure, a cystoscope (a small lighted viewing device) is passed through the urethra into the bladder to directly view both structures. Cystoscopy is indicated when blood cells are detected in a man’s urine. Cystoscopy also may be performed before prostate surgery to guide the surgeon in performing the procedure. Cystoscopy can help the surgeon spot abnormalities of the urethra or bladder.