Q[max]. The rate of urine flow is calculated as milliliters of urine passed per second (mL/s). At its peak, the flow rate measurement is recorded and referred to as the Q[max]. The higher the Q[max], the better the patient's flow rate. Men with a Q[max] of less than 12 mL/s have four times the risk for urinary retention than men with a stronger urinary flow.
The Q[max] measurement is sometimes used as the basis for determining the severity of obstruction and for judging the success of treatments. It is not very accurate, however, for several reasons:
- Urine flow varies widely among individuals as well as from test to test.
- The patient's age must be considered. Flow rate normally decreases as men age, so the Q[max] typically ranges from more than 25 mL/s in young men to less than 10 mL/s in elderly men.
- The Q[max] level does not necessarily coincide with a patient's perceptions of the severity of his own symptoms.
Urinalysis
A urinalysis can detect signs of bleeding or infection. A urinalysis involves a physical and chemical examination of urine. In addition, the urine is spun in a centrifuge to allow sediments containing blood cells, bacteria, and other particles to collect. This sediment is then examined under a microscope. Although urinary infection is uncommon in younger men, it occurs more frequently in older men, particularly those with BPH. A urinalysis also helps rule out bladder cancer.
Pre and Post Massage Test (PPMT)
To rule out prostatitis (infection or inflammation of the prostate gland), a simple test called the Pre and Post Massage Test (PPMT) is about 90% accurate. This test requires two cultures and microscopic examinations of urine samples taken before and after massage of the prostate gland. To massage the prostate the doctor simply inserts a gloved finger into the rectum and presses several times on the prostate. The following results are indicated by findings on cultures after massage:
- Category II prostatitis (Chronic bacterial). Bacteria are found on post-massage.
- Category IIIA prostatitis (Inflammatory chronic pelvic pain syndrome). Leukocytes or other cells are found that indicate inflammation.
- Category IIIB prostatitis (Noninflammatory chronic pelvic pain syndrome). No signs of inflammation or bacteria.
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