Source: National Kidney and Urologic Diseases Information Clearinghouse
Prostate tests may include the digital rectal exam (DRE), the PSA blood test, urinalysis, transrectal ultrasound, prostate biopsy, MRI and CAT scans, urodynamic tests, intravenous pyelogram, abdominal ultrasound.and cystocopy.
Digital Rectal Examination (DRE)
This exam is usually done first. Many doctors perform a DRE as part of a routine physical exam for any man over 50, some even at 40, whether the man has urinary problems or not. You may be asked to bend over a table or to lie on your side holding your knees close to your chest. The doctor slides a gloved, lubricated finger into the rectum and feels the part of the prostate that lies next to it. You may find the DRE slightly uncomfortable, but it is very brief. This exam tells the doctor whether the gland has any bumps, irregularities, soft spots, or hard spots that require additional tests. If a prostate infection is suspected, the doctor might massage the prostate during the DRE to obtain fluid for examination under a microscope.
|Digital rectal exam (DRE)|
PSA Blood Test
To rule out prostate cancer, your doctor may recommend a PSA blood test. The amount of PSA, a protein produced by prostate cells, is often higher in the blood of men who have prostate cancer. However, an elevated level of PSA does not necessarily mean you have prostate cancer. The Food and Drug Administration has approved a PSA test for use in conjunction with a DRE to help detect prostate cancer in men age 50 or older and for monitoring men with prostate cancer after treatment. However, much remains unknown about how to interpret the PSA test, its ability to discriminate between prostate cancer and benign prostate conditions, and the best course of action if the PSAis high.
Because so many questions are unanswered, the relative magnitude of the test's potential risks and benefits is unknown. When added to DRE screening, PSA enhances detection, but PSA tests are known to have relatively high false-positive rates, and they also may identify a greater number of medically insignificant tumors.
The PSA test first became available in the 1980s, and its use led to an increase in the detection of prostate cancer between 1986 and 1991. In the mid-1990s, deaths from prostate cancer began to decrease, and some observers credit PSA testing for this trend. Others, however, point out that statistical trends do not necessarily prove a cause-and-effect relationship, and the benefits of screening for prostate cancer are still being studied. The National Cancer Institute is conducting the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, or PLCO Trial, to determine whether certain screening tests reduce the number of deaths from these cancers. DRE and PSA exams are being studied to see whether yearly screening will decrease the risk of dying from prostate cancer.
Until a definitive answer is found, doctors and patients should weigh the benefits of PSA testing against the risks of followup diagnostic tests and cancer treatments. The procedures used to diagnose prostate cancer may cause significant side effects, including bleeding and infection. Treatment for prostate cancer often causes erectile dysfunction, or impotence, and may cause urinary incontinence.
Your doctor or nurse may ask for a urine sample to test with a dipstick or to examine under a microscope. A chemically treated dipstick will change color if the urine contains nitrite, a byproduct of bacterial infection. Traces of blood in the urine may indicate that a kidney stone or infection is present, or the sample might reveal bacteria or infection-fighting white blood cells. You might be asked to urinate into two or three containers to help locate the infection site. If signs of infection appear in the first container but not in the others, the infection is likely to be in the urethra. Your doctor or nurse might ask you to urinate into the first container, then stop the stream for a prostate massage before completing the test. If urine taken after prostate massage or the prostate fluid itself contains significantly more bacteria, it is a strong sign that you have bacterial prostatitis.
Transrectal Ultrasound and Prostate Biopsy
If prostate cancer is suspected, your doctor may recommend transrectal ultrasound. In this procedure, the doctor or technician inserts a probe slightly larger than a pen into the rectum. The probe directs high-frequency sound waves at the prostate, and the echo patterns form an image of the gland on a television monitor. The image shows how big the prostateis and whether there are any irregularities, but cannot unequivocally identify tumors.
To determine whether an abnormal-looking area is indeed a tumor, the doctor can use the probe and the ultrasound images to guide a biopsy needle to the suspected tumor. The needle collects a few pieces of prostate tissue for examination under a microscope.
|Transrectal ultrasound and prostate biopsy|
Magnetic Resonance Imaging (MRI) and Computed Axial Tomography (CAT) Scans
MRI and CAT scans both use computers to create three-dimensional or cross-sectional images of internal organs. These tests can help identify abnormal structures, but they cannot distinguish between cancerous tumors and noncancerous prostate enlargement. Once a biopsy has confirmed prostate cancer, a doctor might use these imaging techniques to determine how far the cancer has spread. Experts caution, however, that MRI and CAT scans are very expensive and rarely add useful information. They recommend using these techniques only when the PSA score is very high or the DRE suggests an extensive prostate cancer, or both.
If your prostate problem appears to be related to blockage, your doctor or nurse may recommend tests that measure bladder pressure and urine flow rate. You may be asked to urinate into a special device that measures how quickly the urine is flowing and records how many seconds it takes for the peak flow rate to be reached. Another test measures postvoid residual, the amount of urine left in your bladder when you have finished urinating. A weak stream and difficulty emptying the bladder completely may be signs of urine blockage caused by an enlarged prostate that is squeezing the urethra.
Intravenous Pyelogram (IVP)
IVP is an x-ray of the urinary tract. In this test, dye is injected into a vein, and x-ray pictures are taken at 0, 5, 10, and 15 minutes to see the progression of contrast through the kidney and ureter. The dye makes the urine visible on the x-ray and shows any narrowing or blockage in the urinary tract. This procedure can help identify problems in the kidneys, ureters, or bladder that may have resulted from urine retention or backup.
For an abdominal ultrasound exam, a technician will apply gel to your lower abdomen and sweep a handheld transducer across the area to receive a picture of your entire urinary tract. Like the IVP, an abdominal ultrasound can show damage in the upper urinary tract that results from urine blockage at the prostate.
After a solution numbs the inside of the penis, the doctor inserts a small tube through the urethral opening at the tip of the penis. The tube, called a cystoscope, contains a lens and a light system, which allow the doctor to see the inside of the urethra and the bladder. The doctor can then determine the location and degree of the obstruction.
NIH Publication No. 04-5105
Posted January 2006
Update November 2009