COMPREHENSIVE PROSTATE EVALUATION: RADIOLOGIST’S PERSPECTIVE.
As many as 14 million men in the United States have symptoms related to prostate enlargement. Worldwide, approximately 30 million men have symptoms related to prostate enlargement. Then how can we evaluate prostate disease on scientific basis?
In Kashmir, many men above 40 years of age are concerned that they have prostate problem!! They carry a series of ultrasound reports with them and they have been closely watching over time the weight of prostate calculated at the time of ultrasound examination. Many such men are fixed with these reports and become a psychological wreck. What is the science behind these reports and facts about concern of these men?
The prostate gland is a walnut-sized organ located in front of the rectum and right below the bladder (bag which stores urine). Its function is to produce part of the seminal fluid. The prostate gland surrounds the urethra, the tube that carries urine out of the body. In young men and those below 40 years of age, prostate weighs approximately 20 g. Beyond 40 years of age prostate gland starts enlarging in size and weight. In most men by age of 50 years the prostate size doubles and reaches approximately 40 g. Thus enlargement of prostrate is a universal age-related process.
Benign prostatic hyperplasia (BPH) is a noncancerous enlargement of the prostate gland. BPH is a common occurrence in men above 40 years. More than half of men over age 50 have BPH. By age 80, nearly all men have enlarged prostates. So what is the basis behind men following up the weights of their prostates over time and get concerned about it? The issue here is not weight of prostate but whether enlarged prostate as a result of BPH begins to squeeze the upper part of urethra and restricts flow of urine. Only less than half of men with enlarged prostates develop symptoms related to urinary obstruction (called Bladder Outflow Obstruction-BOO). Also prostate size correlates poorly with BOO and large prostates are often seen without symptoms of urinary obstruction and there are many with severe urinary obstruction and disability with prostate size which may be within normal limits or even smaller. This leads us to ponder then how can comprehensive evaluation of prostate be done? This needs a systematic clinical, radiologic and urologic evaluation and this should put concept of following “the weight of prostate alone” men to rest.
First and foremost point in evaluating prostate is to find whether subject has lower urinary tract symptoms (LUTS) and how much these symptoms are affecting quality of life (QOL) of the incumbent. These symptoms include a weak or intermittent urine flow, difficulty starting or stopping urination, a feeling of being unable to empty the bladder completely, or the need to urinate frequently, especially at night. International agencies have developed a scoring system [International Prostate Symptom Score (IPSS)/American Urological Association Symptom Index (AUA-SI)] to quantify these symptoms and this has given a big boost to make initial evaluation of prostate symptoms and show symptom relief or progression over time or after medical or surgical treatment. Seven questions as defined by committee are served to the incumbent and each question is to be scored on a scale from 0 to 5 and all seven question-scores summed up (maximum score 35). Symptoms are classified as mild (score less than 7), moderate (score from 8 to 19) or severe (score more than 20). BPH can cause other urinary symptoms/complications which include urinary retention, renal insufficiency, recurrent urinary tract infections, gross hematuria, bladder calculi and renal failure or uremia (rare in current practice). Also one needs to remember that other diseases of prostate or related organs can cause similar symptoms and this need to be studied methodically.
Most clinicians believe that next step to evaluate prostate is to do “Digital Rectal Examination (DRE)” and estimation of prostate specific antigen (PSA). DRE involves introducing a gloved and greased finger into the rectum to assess the size of the prostate and to detect any abnormal nodules (lumps) that may require further investigation. A PSA test measures the level of prostate-specific antigen (PSA) in the patient's blood. It is the standard screening test for prostate cancer. A PSA is recommended annually for all men over 50 years old and for men over 40 who are at high risk for prostate cancer. Normal values of PSA are less than 4 ng/mL. If levels are more than 10 ng/mL, a search for prostate cancer is mandatory. In patients with BPH levels between 4 to 10 ng/mL may be seen. Also around 20 percent patients with documented prostate cancer, PSA levels may be within normal limits. So normal PSA level does not exclude chances of prostate cancer. Drug used to manage BHP may also interfere with PSA level and so it is important to test PSA before starting drug therapy for BPH.
Next it is useful to conduct a urinalysis (urine examination) to detect signs of infection or bleeding and serum creatinine to evaluate kidney function. Although urinary infection is uncommon in younger men, it occurs more frequently in older men, particularly those with BPH. A urinalysis showing hematuria (blood) may give clue to bladder cancer. If prostatitis (infection of prostate) is suspected, a simple test called the Pre- and Post- Massage Test (PPMT) is about 90 percent accurate. This test requires culture and microscopic examination of urine samples taken before and after massage of the prostate gland.
Uroflometry is another useful test to assess the severity of BOO and every incumbent suspected to have prostate disease/symptoms needs to undergo this test. The patient is instructed not to urinate for several hours before the test and to drink plenty of fluids so he has a full bladder and a strong urge to urinate. To perform the test, a patient urinates into a special toilet equipped with an uroflometer. 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 is 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 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.
Post-void Residual Urine (PVR) is another important test to assess BOO. This is calculated by the amount of urine left in bladder after urination. Normally, about 20 mL or less of urine is left; more than 200 mL is a definite sign of abnormalities. Measurements in between require further tests. The best way to evaluate PVR is at transabdominal ultrasound examination. It can also be measured by passing a catheter, a soft tube, which is inserted into the urethra within a few minutes of urination.
Where does role of ultrasound lie in evaluating prostate diseases? Two types of Ultrasound examinations can be used to evaluate prostate: (i) Transabdominal ultrasonography uses a device (transducer) placed over the lower abdomen and visualizes prostate through full bladder. . It can give an accurate measure of post-void residual urine (PVR). Transabdominal ultrasound is adequate in detecting prostate size; however, this is suboptimum in detecting abnormalities of prostate cancer. (ii) Transrectal ultrasonography (TRUS) uses a special rectal probe/transducer for assessing the prostate. TRUS is significantly the most accurate method for determining prostate volume/size. It is very useful to detect abnormalities seen in prostate cancer. A Doppler study is usually done at TRUS to assess prostate blood flow and improve on detecting prostate cancer. Also TRUS is used to take transrectal prostate biopsies should prostate cancer be suspected. Apart from evaluating prostate size and structure, ultrasound is useful for detecting kidney damage, tumors, and bladder stones and for this Transabdominal ultrasound is adequate to evaluate these abnormalities.
Cystoscopy is a specialized urologic procedure and may be performed in men diagnosed with BPH, particularly if they are surgical candidates or if other urinary tract problems are suspected. Such problems include blood in the urine, infection, bladder cancer, or prior surgery or injury. The physician can determine the presence of a number of problems, including enlargement of the prostate, obstruction of the urethra or neck of the bladder, anatomical abnormalities, or the presence of stones. In this procedure, a flexible or rigid fiberoptic tube (an endoscope) is inserted into the urethra to allow doctors to view the lower urinary tract. The procedure is not without risks. Complications are uncommon but can include allergic response to anesthetic, urinary tract infection, bleeding, and urine retention.
Based on the above information available and severity of disability, clinician can take a decision regarding ideal treatment needed for managing BPH. The management may be either (i) life style modification alone to reduce prostate symptoms, (ii) drug treatment to improve urine flow and reduce prostate size or (iii) remove enlarged prostate either at Transurethral prostatectomy (TRUP), Transurethral needle ablation (TUNA) or Transurethral microwave therapy (TUMT) or open prostatectomy as deemed fit on clinical grounds.
The article has been written to stress that evaluation of prostate diseases needs an algorithm as defined in the article and ultrasound examination alone giving weights of prostate should be read and evaluated with other parameters and not in isolation.
Dr. Naira Sultan Khuroo
MBBS (KU), Fellowship Medical Imaging & Radiology (KFSH & RC Riyadh, KSA), Fellowship Fetal Medicine Ultrasound (Fetal Medicine Foundation UK).
Former Fellow, Body Imaging, King Faisal Specialist Hospital& Research Centre, Riyadh, KSA.
Consultant Radiologist Digestive Diseases Centre Dr. Khuroo’s Medical Clinic, Sector 1, SK Colony Qamarwari, Srinagar, Kashmir, J&K, 190010 India.
Medical Registration: i. J&K Medical Registration Council-9303 Dated Sept 8th 2006, ii. Saudi Council Health Specialties License Number 301 Sept 14th 2000.