Patients selected for TURP should have clinical symptoms and signs caused by bladder outlet obstruction from BPH, because this procedure is thought to work by removal of obstructing prostate tissue. Most patients (90%) who undergo TURP do so because of the bothersome irritative and obstructive symptoms associated with BPH, termed prostatism, or more recently, lower urinary tract symptoms (LUTS) (3). Other patients, however, are treated for increased postvoid residual urine, urinary retention, urinary tract infection, hematuria, renal insufficiency, and vesical calculi.
Conditions with symptoms that mimic those of BPH must be eliminated during the preoperative assessment. The medical history should search for clues that suggest neurologic, infectious, and other causes that can result in lower urinary tract dysfunction and similar symptoms. Although the symptoms of BPH are not specific for the disorder, determining the severity of these symptoms is quite helpful when evaluating a patient for possible TURP. A useful tool is the American Urological Association (AUA) Symptom Index, which has been found to be both valid and reliable (4). It cannot be used alone to diagnose BPH, however, because the symptoms measured are not specific for the disease.
Physical examination, at minimum, should include palpation of the lower abdomen for evidence of bladder distention and digital rectal examination of the prostate. The latter should assess for prostate consistency, symmetry, and size. An estimate of prostate size, albeit inaccurate by digital examination, is important because there is a limitation to the amount of tissue that can be safely resected transurethrally. Bladder outlet obstruction caused by very large prostates (>75 g) is generally better treated with an open prostatectomy (suprapubic or retropubic) (5). Decreased or absent anal sphincter tone, perineal sensation, or bulb-ocavernosus reflex suggests a neurologic process and should be studied further to determine the correct diagnosis. Urinalysis is necessary to detect the presence of urinary tract infection and can also reveal hematuria, which may suggest the presence of urinary tract calculi or neoplasia. Patients with hematuria but no infection should undergo upper tract imaging (intravenous pyelogram, computed tomography [CT] scan, or
renal ultrasound), urine cytology, and cystoscopy. When performed, cystoscopy may reveal the secondary effects of obstruction on the bladder such as the presence of trabeculation, cellules, and diverticuli (Fig. 1). Bladder calculi, which form as a result of incomplete emptying associated with obstruction, may also be detected. Cystoscopy findings, in particular occlusion of the urethra by the prostatic lobes, cannot reliably predict bladder outlet obstruction from BPH and should not be used alone to justify proceeding with a TURP (Fig. 2).
Whether urodynamic studies are necessary in the evaluation of patients with LUTS caused by bladder outlet obstruction is controversial. Simple studies such as postvoid residual urine measurement and noninvasive uroflowmetry are generally well accepted. Nevertheless, their ability to predict obstruction and successful surgical outcome has not been established. A postvoid residual urine measurement can be helpful because an elevated residual level implies a problem with either detrusor contractility or outlet resistance. Elevated residual urine by itself, however, does not necessarily indicate obstruction. Basic cystometry can provide useful information about bladder compliance, capacity, and contractility, but it is not recommended as a necessary
preoperative study. The gold standard test is the pressure-flow study, in which detrusor contractility and urinary flow are measured simultaneously. Elevated detrusor pressure in conjunction with low urinary flow rate is evidence of bladder outlet obstruction. This diagnosis is further supported by the findings of external sphincter relaxation and poor posterior urethral opening on electromyography and fluoroscopy, respectively. Those who favor the use of urodynamic studies believe that unequivocal bladder outlet obstruction should be demonstrated before a procedure that is designed to eliminate it is performed. On the other hand, those in opposing camps believe that the expense and invasiveness of urodynamics, and knowledge that most patients do well after TURP despite urodynamic findings, argue against performing this procedure routinely. Although the usefulness of preoperative urodynamic studies in the average patient can be debated, if there is clinical evidence that suggests a potential underlying neurologic cause for voiding dysfunction (i.e., diabetes mellitus, Parkinson's disease, multiple sclerosis), urodynamic studies must be performed before considering TURP.
The Agency for Health Care Policy and Research published guidelines for the evaluation of men with symptoms caused by BPH (2).
Recommended evaluations include a medical history, physical examination, urinalysis, and serum creatinine level. In addition, it is recommended that the AUA Symptom Index be administered initially and used as a measure of a treatment efficacy at follow-up. Studies felt to be optional include noninvasive uroflowmetry, postvoid residual urine measurement, pressure-flow urodynamics, and urethrocystoscopy. The latter is recommended for consideration only when invasive treatment is being planned or when there is evidence of hematuria, urethral stricture (or its risk factors), bladder cancer, or prior lower urinary tract surgery (particularly TURP). Filling cystometry, initial evaluation with urethrocystoscopy, and upper tract imaging studies were not felt to be necessary for the evaluation of the typical patient with BPH.
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