What tests may be involved with the diagnosis of BPH?
Not everyone with lower urinary tract symptoms (LUTs) suggestive of BPH will require special tests to make a diagnosis. However, in certain individuals further testing may be helpful in guiding the management.
Uroflow: A uroflow measurement is a totally noninvasive test. The patient, with a full bladder, voids into a special urinal that has a flowmeter, which measures both the urine flow in milliliters per second as well as the total volume voided. This is plotted onto a piece of paper, and there are nomograms available that allow the doctor to compare the patient's urine flow rate with accepted standards. The uroflow is typically done in the physician's office at the time of the patient's visit. A low urine flow rate is suggestive, but not definitive, for bladder outlet obstruction, which may be caused by BPH or a urethral stricture. However, in the individual whose bladder does not contract adequately, the urine flow rate may also be low. The urine flow rate can also look better than it really is if you push with your abdominal muscles while voiding. Thus, although helpful, it is not entirely accurate.
Bladder ultrasound/scanner PVR: A bladder ultrasound is performed by placing an ultrasound probe, which is like a plastic microphone, on the patient's lower abdomen over the bladder. This is done after the patient has been asked to void, and the probe calculates how much
Figure 20. International Prostate Symptom Score (IPSS).
urine is left in the bladder. This procedure is totally painless, and a medical assistant, a nurse, or a physician performs this in a physician's office. Bladder scanner/ ultrasound postvoid residual determination is often performed in those men who present with a complaint of the feeling of incomplete bladder emptying and/or those men with urinary incontinence.
Cystoscopy: Cystoscopy means literally to look into the bladder. A cystoscope is either a rigid or flexible instrument that has a lens at one end and is connected to a light source. The instrument permits the urologist to look up through the penis and through the prostate and into the bladder. If a rigid cystoscope is used, the patient is placed on his back with his feet in stirrups (Figure 21). If a flexible cystoscope is used, the patient is positioned flat on his back with his feet out straight or the supine position. A cystoscopy can be performed with either the patient under general, spinal, or local anesthesia and can
Figure 21. Position for cystoscopy.
Crowley, LV. An Introduction to Human Disease. 6th ed. Jones and Bartlett Publishers, LLC. Sudbury, MA, 2004.
be done in either the physician's office or the operating room in the hospital. Not all men with BPH symptoms need cystoscopy. If your doctor notes that you have blood cells in your urine (microscopic hematuria) or you have seen blood in your urine (gross hematuria) you will need a cystoscopy in addition to other tests. In those men with BPH who are considering surgical or minimally invasive treatment the urologist will often perform a cystoscopy before the procedure to make sure that you are a candidate for the procedure and that there are no other abnormalities (bladder stones, bladder tumors, urethral strictures) present. In those individuals who don't respond to medical therapy, a cystoscopy may be indicated.
A urodynamic study is a test used to assess how well the bladder and urethra are performing their job of storing and releasing urine.
Urodynamic tests can help your doctor assess such symptoms as:
Urinary incontinence Urinary frequency Urgency
Problems with starting one's stream (hesitancy) Painful urination Incomplete bladder emptying Recurrent infections
A urodynamic study is comprised of a series of tests. Depending on your symptoms, you many need some or all of the components. Urodynamic studies are often performed in the doctor's office or in a specialized outpatient area.
Little preparation is needed for a urodynamic test. You can eat prior to the test. Your doctor may ask you to come in with a full bladder.
The urodynamic study may start with a uroflow. The uroflow measures the rate of urination in cubic centimeters or milliliters per second (see Question 34). After the uroflow, the cystometrogram (CMG) component of the urodnynamic study is performed. The CMG assesses pressure in the bladder during bladder filling and urinating. After voiding, a specialized catheter is placed into your urethra and passed into your bladder. The catheter is taped in place to prevent if from falling out during the study. Your bladder is emptied and the volume left behind in your bladder after voiding, the postvoid residual (PVR), is recorded. Once the catheter is secured in place and your bladder is emptied, the catheter is connected to a special pressure monitor, a transducer, and to the tubing that supplies the sterile fluid. A separate catheter is placed into your rectum which allows the doctor to measure pressures within your abdomen. The rectal catheter is also connected to a transducer. In order to assess the activity of your pelvic floor muscles skin patch electrodes or small needle electrodes will be placed in the area near your anus. These electrodes measure activity in your pelvic floor muscles, which also surround the urethra. This type of study is called electromyography (EMG). The EMG measures activity in the muscles of the pelvic floor. During the urodynamic study, fluoroscopy (X-ray) may be used to visualize your bladder and urethra during bladder filling and voiding. If X-ray is used during the study it is called video-urodynamics.
After placement of the two catheters and the electrodes, the CMG is started. Sterile fluid is instilled into your bladder at a rate specified by your doctor. A computer screen displays the pressures in your abdomen, your bladder, and the activity of your pelvic floor muscles.
Shortly after starting the study you will be asked to cough or bear down to ensure that the catheters are in the correct position and transducers are working properly. While your bladder is filling with the sterile fluid, your doctor will ask you to indicate when you first feel the urge to void and when you feel a strong urge to void. The volumes in your bladder at each of these times will be recorded.
Normally, during bladder filling the bladder pressure remains very low and the bladder muscle is quiet (stable) until one feels the urge to urinate and decides to void. During voiding, the bladder pressure quickly increases and then promptly decreases as soon as urination is completed. Periodic increases in bladder pressure during the study are referred to as involuntary bladder contractions/detrusor overactivity and may contribute to the symptoms of frequency, urgency, and urge incontinence. The CMG also evaluates bladder compliance. Poor compliance, the inability to store urine at low pressures, may cause damage to the kidneys and be a source of urine leakage.
During the study, when you feel a strong urge to urinate, the fluid infusion will be stopped and you will be asked to void. During urination the bladder pressures and the urine flow rate are monitored. These values are then plotted on a nomogram called a pressure flow study. This study is particularly helpful in males as it helps determine if there is any significant obstruction to the outflow of urine. During voiding, the flow rate and electromyelogram (EMG) are assessed. This is helpful in ensuring that there is appropriate relaxation of the pelvic floor muscles prior to voiding and that this relaxation continues throughout voiding.
In some cases, a specialized dye is used to fill your bladder. This allows your doctor to take X-rays periodically during the study to look at your bladder and urethra.