BPH diagnosis and tests

by Anthony Balchunas, MS, PA-C

Tests for BPH can rule out more serious conditions when a man has symptoms such as slow urine flow, an intermittent urinary stream, dribbling, increased frequency of voiding, and sudden urges to void.

BPH (benign prostatic enlargement) is a very common condition affecting approximately 40% of men age 60 and older and 90% of men over age 80¹. Because of the ageing population, the absolute number of patients affected by BPH will continue to rise and the burden on the health care system will increase.

Multiple community-based studies have clearly shown the progressive nature of BPH and the ever increasing impact on one's health and well-being. Indicators of disease progression include worsening of symptoms, frequent occurrence of urinary tract infections (UTIs), development of bladder stones, and decrease in urinary flow secondary to increase in prostate size. Negative clinical outcomes such as acute urinary retention (inability to void), the development of socially unacceptable urinary incontinence, and the need for surgery have been shown to occur more commonly in men with progressive BPH². The typical male experiencing progressive symptoms associated with BPH, left untreated, has a 23% lifetime risk of developing acute urinary retention (AUR)³. If a man has obstructive urinary symptoms (i.e. weak stream, difficulty starting, dribbling) and is over the age of 60 years, he has a 39% probability of undergoing surgery related to the prostate within 20 years.⁴

Despite being so prevalent among aging men, BPH is very much under-diagnosed and under-treated. Prior to the advent of medications which effectively control/reduce symptoms and clinical problems associated with BPH, the urologist was the medical professional most experienced and qualified to diagnose and treat BPH. Management was predominantly surgical, with the TURP (trans-urethral resection of the prostate) being the gold standard of treatment.

Since the late 1990's, the management of prostate disease has been steadily shifted to the primary care provider.⁵ Several factors have accounted for this trend including the development of medications that effectively treat BPH and its associated symptoms. This allowed for the non-surgical management of BPH by qualified practitioners not specialized in urology. The ever-ageing population has also overwhelmed the resources of the urology community thus requiring primary care providers to help ease the burden of health care delivery. A 2005 National Institute of Health survey reported that at least 6.3 million American men over 30 years of age are affected by enlarged prostate, accounting for 6.4 million physician visits.⁶ These numbers will continue to increase as the "baby-boomers" continue to age.

The importance of diagnostic tests when BPH is suspected

Symptoms such as slow urine flow, an intermittent urinary stream, dribbling, increased frequency of voiding, and sudden urges to void (sometimes associated with leakage of urine) are often referred to as "LUTS" (lower urinary tract symptoms). These symptoms are not specific to enlarged prostate and can be associated with many other urological and non-urological conditions. Examples of other urological problems that can cause similar symptoms include urinary tract infection, urinary stone disease, prostate cancer, prostatitis, and bladder cancer. Non-urological conditions such as diabetes, Parkinson's disease, multiple sclerosis, congestive heart failure, and lumbo-sacral disk disease can also cause similar symptoms.⁷ Medications such as tricyclic antidepressants, anti-cholinergics, narcotics, antihistamines, diuretics, and decongestants can also provoke negative changes in urinary symptoms.⁸

With so many other clinical problems potentially provoking bothersome changes in urinary symptoms, it is important that clinicians consider standard methods for evaluating patients with LUTS. Not only does this help to diagnose other potentially serious conditions, it also increases the likelihood that an appropriate and effective treatment will be instituted. As an example, in one study it was shown that a significant number of older men with LUTS did not have significant obstruction secondary to an enlarged prostate. Instead, bothersome urinary symptoms resulted from over-activity of the bladder muscle.⁹

Basic Evaluation of BPH/LUTS

Clinical evaluation of LUTS should always start with basic questions about the nature of one's symptoms. Simple questions such as "do you feel the need to empty your bladder more frequently than other individuals?" or "when you empty your bladder, is your stream slow?" can give clues as to whether or not the presence of BPH should be suspected. The natural history of these symptoms can also help if BPH is suspected (slow gradual progression of symptoms as opposed to sudden onset is suggestive of BPH).

Standardized questionnaires such as the International Prostate Symptom Score (IPSS) can be helpful to assess baseline urinary symptom severity; scores can also be utilized to assess treatment response and/or symptom progression in a follow-up period.¹⁰ It should be emphasized, however, that the IPSS alone should not be used to establish a diagnosis of BPH. LUTS are not unique to BPH alone and, as mentioned previously, other conditions both urological and non-urological can cause LUTS. If the IPSS is used when BPH is suspected; it may help to raise further suspicion and lead to more specific tests which aid in the diagnosis of BPH.

Physical Exam for BPH

A detailed physical exam helps the clinician to look for clues of other medical problems that might contribute to BPH symptoms (LUTS). A distended lower abdomen may suggest a poorly emptying bladder. Focused neurological exam might suggest problems that contribute to poor bladder function. A genital exam helps to rule out conditions such as meatal stenosis (narrowing of the urethral opening) or urethral masses which may cause symptoms such as a slow stream or dribbling at the end portion of voiding. A digital rectal exam (DRE) should always be performed to look for signs of prostate infection, prostate inflammation, and/or prostate cancer. Much controversy exists as to whether or not the DRE is accurate in predicting prostate size. While some studies suggest that DRE provides a relatively crude estimate of prostate size, others suggest that DRE tends to over-estimate the size of small prostates and under-estimates the size of large prostates.¹¹

While having a reasonable estimate of prostate size may be clinically relevant in some cases, over-emphasis on "estimated" prostate size obtained from digital rectal exam is not helpful. The reason for this is straightforward: size of the prostate does not correlate well with degree of bladder outlet obstruction, nor does it correlate with symptom severity. Put simply, men with small prostates can have a significant degree of outlet obstruction as manifest by symptoms such as slow voiding stream, difficulty initiating a voiding stream, and difficulty completely emptying the bladder. They can also have symptoms which are more bothersome than those experienced by other men with a lesser degree of bulky prostate enlargement.^{12, 13}

Laboratory Tests for BPH

All male patients presenting for evaluation of urinary symptoms should have a urinalysis performed to rule out urinary tract infections and hematuria (blood in the urine). Urinary tract infection is no doubt one of the more common non-BPH problems that can cause symptoms similar to those experienced with BPH. Microscopic hematuria (blood can be seen in a urine specimen under the microscope) can be associated with BPH; as the prostate grows, it tends to be more vascular. It should never be assumed, however, that microscopic blood in the urine is caused by a benign process. More serious pathologic problems such as kidney stones and renal/ureteral/bladder tumors can cause varying degrees of gross and/or microscopic hematuria. Current recommendations from the American Urological Association advise that a referral be made for urological evaluation if any gross bleeding occurs with voiding or if a significant degree of microscopic hematuria is identified.

PSA or prostate specific antigen is a serum marker for prostate activity (measured by a simple blood test). Despite the fact that PSA measurement is commonly utilized as a screening test for prostate cancer, it must be emphasized that there is significant overlap in PSA values of men with BPH and men with prostate cancer.¹⁴ The utility of PSA as a screening test for prostate cancer is quite controversial; however, as a screening test for BPH the role of PSA is more clearly defined. Multiple large clinical trials have consistently shown a strong correlation between serum PSA levels and prostate size.¹⁵ If PSA is appropriately used as a surrogate marker for prostate size, it may help determine which (if any) treatment is necessary in men presenting with BPH symptoms.

Uroflow for BPH

A Uroflow is a simple non-invasive study which electronically measures urine flow rate throughout the entire voiding cycle. This test can easily be performed in the clinician's office by simply having a patient void in a special receptacle. By measuring flow rate, clinicians can relatively predict whether or not bladder outlet obstruction is truly present and to what degree. Men with maximum flow rates greater than 15cc/sec are generally thought to be unobstructed and may not respond as favorably to medical and/or surgical treatment. On the other hand, those with blunted flow rates may see improvements with appropriate therapy. It should be emphasized that the results of uroflowmetry are non-specific for causes of symptoms. For example, an abnormally low flow rate may be caused by a poorly functioning bladder muscle rather than bladder outlet obstruction secondary to BPH.¹⁶ Despite its limitations, uroflowmetry can be an important tool to predict who might benefit most from BPH therapy. It may also have a role in gauging clinical response once therapy (either medical or surgical) has been instituted.

Post-void Residual Urine (PVR) for BPH

Post-void residual urine is defined as the volume of urine that remains in the bladder after one has completed voiding. Studies show that the amount of residual urine is usually very low with approximately 78% of men having a PVR of less than 5 ml and virtually 100% of men having a PVR less than 12 ml.¹⁷ Normal bladder capacity is roughly 300-500 ml, therefore, measurement of PVR can give a basic estimate of one's ability to efficiently empty the bladder.

PVR measurement can be done simply and non-invasively with a hand held scanner that utilizes sound waves to estimate volume of urine in the bladder. If this type of scanner is unavailable, standard ultrasound equipment can be used to give a similar estimate. Passing a catheter into the bladder and draining residual urine is another method of determining PVR. This method is not typically recommended as it is invasive and can cause significant patient discomfort.

It is commonly thought that as BPH progresses, increased obstruction leads to less efficient bladder emptying (higher PVR's). On the contrary, clinical studies show significant intra-individual variability in PVR measurement, whether or not BPH is present. PVR measurements correlate poorly with clinical symptoms of BPH and inconsistently predict better or worse outcomes with medical and/or surgical therapy. Despite its clinical limitations, PVR measurement is thought to be a good "safety parameter" in men with BPH. By monitoring PVR values periodically over time, clinicians can make more informed decisions on which treatment options for BPH might be most suitable. It may also help clinicians to determine if more invasive testing is necessary (if the PVR is high on initial evaluation or if the PVR significantly rises over time).

Pressure-Flow Studies for BPH Diagnosis

Pressure flow studies, otherwise known as "urodynamics" are tests that measure the pressure forces generated by the bladder muscle during voiding and the rate of urine flow. By measuring these parameters simultaneously one is able to distinguish the difference between a low urine flow secondary to BPH/bladder outlet obstruction and a low flow caused by poor bladder muscle function. Individuals with diabetes, multiple sclerosis, and/or various other neurological disorders often develop a "neurogenic bladder". In this situation, the bladder muscle loses its ability to contract forcefully enough to expel urine. The end result is a slow voiding stream and either the inability to empty the bladder efficiently or complete urinary retention (one is unable to void at all despite having a full bladder).

Although the test/re-test reliability of pressure flow studies appears to be reasonable¹⁸ , controversy exists about the most appropriate clinical use of pressure flow studies. The test is somewhat invasive as it requires placement of a small catheter within the bladder and placement of a pressure "balloon" within the rectum. The test is started with the patient voiding and emptying the bladder as best as possible. The clinician then places a catheter in the patient's bladder; any remaining urine is drained and the volume is recorded (post-void residual).

After drainage of any residual urine is complete, careful filling of the bladder with sterile water begins. During the filling phase patients communicate with the tester indicating at what point they feel "somewhat full", "very full", and full enough that the need to void cannot be further delayed. Bladder volume at these different time points is recorded giving the tester some sense of the patient's "functional bladder capacity". Functional bladder capacity is defined as the amount of urine one can hold before experiencing the strong desire to void. Once the bladder is full, the patient is asked to void. During the voiding phase urine flow and bladder pressures are simultaneously measured. By measuring these two parameters, the tester is able to distinguish poor flow rates secondary to poor bladder muscle function from poor flow rates secondary to BPH. In patients with significant bladder outlet obstruction secondary to BPH, flow rates will be low while bladder pressures are elevated. When bladder muscle function has deteriorated, bladder pressure is generally reduced.

Some studies suggest that pressure flow tests are helpful to predict which BPH patients might be most appropriate for invasive surgical therapy; other studies show limited benefit. Despite inconsistencies in the scientific data, most experts agree that pressure flow studies do have a valuable role in evaluating select patients who present for evaluation and treatment of presumed BPH. By having a better understanding of the function of the bladder muscle, more appropriate treatment can be prescribed in patients with proven bladder dysfunction who do not have evidence of bladder outlet obstruction secondary to BPH.

Urethrocystoscopy for BPH Diagnosis

Urethrocystoscopy involves the insertion of a fiber optic camera into the urethra, through the middle of the prostate, and into the bladder. This procedure is somewhat invasive and is often done in an outpatient surgery center where mild intra-venous sedation can be given. It is also commonly performed in an office based setting where smaller "flexible"-type scopes are used and discomfort is reduced by the pre-procedure placement of anesthetic jelly within the urethra.

During the procedure, the urethra is carefully examined for evidence of strictures (scars). The intra-prostatic portion of the urethra is also carefully examined and the length of the prostate as well as the amount and configuration of the prostatic tissue is noted. Finally, the bladder is entered and examined carefully for tumors, stones, and/or foreign bodies.

The use of urethrocystoscopy for routine evaluation of BPH is not generally recommended. The test is recommended for men with a history of gross and/or microscopic blood in the urine (hematuria), urethral stricture disease, bladder cancer, or prior surgery of the lower urinary tract. Urethrocystoscopy can also be considered in men who have chosen (or who have been recommended) for prostate surgery to help determine which type of procedure might be most appropriate.

Imaging of the Urinary Tract in BPH Diagnosis

Urinary tract imaging can be done with a variety of modalities including magnetic resonance imaging (MRI), CT scan, ultrasound, and plain film radiographs. An IVP (intravenous pyelogram) involves performing a series of plain films of the kidneys, ureters, and bladder after iodine contrast agent is infused intravenously. Not only does this test allow for anatomical assessment of the upper urinary tract, it gives some information on function as well. If the kidneys are poorly functioning or are obstructed in some way, the IV contrast will not be seen beyond the kidneys. If severe obstruction or minimal kidney function is present, contrast may not be seen at all.

There are certain situations where imagining of the urinary tract is mandatory; the type of study chosen by the clinician depends on what sort of problem is being evaluated and what type of information about the urinary tract is desired. Examples of problems requiring radiographic evaluation include: blood in the urine (hematuria), urinary tract infection, poor kidney function (renal insufficiency), history or suspected history of urinary stone disease, or history of urinary tract surgery.^{10, 14}

Many patients with BPH do not have any of the above mentioned problems and thus imaging would be unnecessary in the routine evaluation and management of BPH. Inappropriate use of imaging studies not only increases the cost of health care delivery, it may also unnecessarily expose patients to radiation when certain specific studies are performed (CT scan, plain film).

In summary, BPH is a common clinical condition experienced by aging men that can lead to significant deterioration in quality of life and medical morbidity. An appropriate evaluation is easy to perform by qualified medical professionals if proper guidelines are followed. Basic evaluation rarely requires any invasive testing; these may, however, be quite helpful in more advanced cases of BPH or where other problems such as infection, stones, or hematuria coexist.

References

Roehrborn CG, McConnell JD. Etiology, Pathophysiology, Epidemiology, and Natural History of Benign Prostatic Hyperplasia, 8th ed. Philadelphia: Campbell's Urology, 2002.
Emberton M, Cornel EB, Bassi PF et al. Benign prostatic hyperplasia as a progressive disease: a guide to the risk factors and options for medical management. Int J Clin Pract 2008; 62: 1076-86.
Jacobsen SJ, Girman CJ, Guess HA et al. Natural history of prostatism: longitudinal changes in voiding symptoms in community dwelling men. J Urol 1996; 155: 595-600.
Arrighi HM, Metter EJ, Guess HA, Fozzard JL. Natural history of benign prostatic hyperplasia and risk of prostatectomy. The Baltimore Longitudinal Study of Aging. Urology 1991; 38: 4-8.
Fawzy A, Fontenot C, Guthrie R, Baudier MM. Practice patterns among primary care physicians in benign prostatic hyperplasia and prostate cancer. Fam Med. 1997;29:321-325.
Kidney and Urologic Diseases Statistics for the United States. National Institute of Diabetes and Digestive and Kidney Diseases. Available at: http://kidney.niddk.nih.gov/kudiseases/pubs/kustats/.
Gades NM, Jacobson DJ, Girman CJ, Roberts RO, Lieber MM, Jacobsen SJ. Prevalence of conditions potentially associated with lower urinary tract symptoms in men. BJU Int. 2005;95:549-553.
Dull P, Reagan RW Jr, Bahnson RR. Managing benign prostatic hyperplasia. Am Fam Physician. 2002;66:77-84.
Oelke M, Baard J, Wijkstra H, de la Rosette JJ, Jonas U, Höfner K. Age and bladder outlet obstruction are independently associated with detrusor over-activity in patients with benign prostatic hyperplasia. Eur Urol. 2008 Aug;54(2):419-26.
McVary KT, Roehrborn CG, et al: American Urological Association Guideline: Management of Benign Prostatic Hyperplasia (BPH). Revised 2010. Available at: http://www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines/main-reports/bph-management/authors.pdf.
Roehrborn CG, Girman CJ, Rhodes T, et al: Correlation between prostate size estimated by digital rectal examination and measured by transrectal ultrasound. Urology 1997;49:548-557.
Barry MJ, Cockett ATK, Holtgrewe HL, et al: Relationship of symptoms and prostatism to commonly used physiologic and anatomical measures of the severity of benign prostatic hyperplasia. J Urology 1993;150:351-358.
Yalla SV, Sullivan MP, Lecamwasan HS, et al: Correlation of American Urological Association Symptom Index with obstructive and non-obstructive prostatism. J Urology 1995;153:674-686.
Dennis L, Griffiths K, Khoury S, et al: Proceedings from the 4th International Consultation on BPH. Plymouth, United Kingdom, Health Publication, 1998.
Roehrborn CG, Boyle P, Gould AL, et al: Serum prostate specific antigen as a predictor of prostate volume in men with benign prostatic hyperplasia. Urology 1999;53:581-589.
Chancellor MB, Blaivas JG, Kaplan SA, et al: Bladder outlet obstruction versus impaired detrusor contractility: The role of uroflow. J Urology 1991;145:810-812.
Di Mare JR, Fish SR, Harper JM, Politano VA: Residual urine in normal male subjects. J Urology 1963;96:180-181.
Rosier PF, de la Rosetta JJ, Koldewijn EL, et al: Variability of pressure flow analysis parameters in repeated cystometry in patients with benign prostatic hyperplasia. J Urology 1995;153:1520-1525.