questions_Urology

Stress incontinence occurs when increases in intra-abdominal pressure lead to sphincter opening in the absence of a bladder contraction. It is the most common cause of urinary incontinence in younger women and the second most common in older women. Also, it may occur in men after a radical or transurethral prostatectomy. Stress urinary incontinence in women most often occurs as a result of insufficient urethral support from pelvic endofascia and muscles.

Overflow incontinence, the most common cause of urinary incontinence in men, is due to detrusor weakness and/or bladder outlet obstruction. Leakage is typically small in volume, but its continual nature may lead to significant wetting. The postvoid residual volume is elevated, and urinary stream may be weak. Dribbling, intermittency, hesitancy, frequency, and nocturia are also symptoms.

Bladder outlet obstruction is the second most common cause of urinary incontinence in older men, resulting from benign prostatic hyperplasia, prostate cancer or urethral stricture. Most obstructed men do not have urinary incontinence. Detrussor overactivity occurs in approximately 2/3 of men with obstruction, resulting in urge symptoms. Overflow incontinence, in these cases, occurs when obstruction causes detrusor decompensation.

Urge incontinence is abrupt, precipitant urgency with moderate to large urinary leakage, often in association with nocturia and frequency. Cause of urge incontinence is presumed to be uninhibited bladder contractions and detrusor overactivity. Detrusor overactivity has, however, been found in continent, healthy elderly individuals, suggesting that overactivity alone is not enough to cause incontinence. Detrusor overactivity may be caused by interruption of CNS inhibitory pathways in the case of stroke or cervical stenosis, etc. Bladder irritation caused by infection, bladder stones, inflammation or neoplasms also may lead to detrusor overactivity. It appears that overactivity of the detrusor muscle may be related to aging also, and it is idiopathic in many cases.

Multiple pregnancies are implicated in development of stress incontinence by weakening of the pelvic floor muscles.

Hematospermia in men younger than 40 years is a benign condition. When evaluated in prospective studies, in about 1/2 of the cases no abnormalities were found and most of the remaining patients had self-limited inflammatory causes (prostatitis, urethritis). No evaluation beyond history, physical examination, and urinalysis is necessary for such patients. For most patients, it is self-limited and usually does not recur. In men older than 40 years, the most common cause is prostatic calculi, but about 10% of patients have a malignancy. Transrectal ultrasound is the most appropriate initial imaging procedure for men in this age group.

Educational objective: Understanding the etiology of struvite kidney stones.

Struvite stones are associated with urinary tract infections caused by Proteus and Klebsiella. Those stones are composed of magnesium ammonium phosphate (struvite), often in combination with calcium carbonate – apatite. Normal urine is undersaturated with ammonium phosphate and struvite stone formation only can occur if ammonia production is increased and when urinary pH is elevated (this decreases the solubility of phosphate). Both situations are present during the infections by Proteus or Klebsiella, the urease-producing organisms. Urease breaks down urinary urea into ammonia and carbon dioxide. The ammonia combines with water and the net result is increased availability of ammonium in alkaline urine.

Educational objective: Understand characteristic findings in hematuria from different parts of urinary tract.

One of the first steps in the evaluation of a patient with hematuria is try to distinguish between glomerular and extraglomerular bleeding. Careful evaluation of the urine may help to establish the correct diagnosis.

The presence of red cell casts is virtually diagnostic of glomerulonephritis or vasculitis. Absence, of course, does not exclude glomerular disease.

Evaluation of red cell morphology also may be helpful because they are typically uniform and round if bleeding is extraglomerular, and dysmorphic (marked variability of the size, and change of shape) with glomerular source of bleeding.

Heavy protein excretion (above 500 mg/day) is also strongly suggestive of a glomerular lesion (hematuria alone does not cause increase in the proteinuria).

Blood clots, if present, are almost indicative of extraglomerular bleeding.

Urine color also may be suggestive; extraglomerular bleeding causes red to pink color while glomerular bleeding tends to give a brownish Coca Cola color.

Educational objective: Review risk factor for calcium renal stones.

Renal stone formation occurs when normally soluble material (e.g. calcium) supersaturates in the solution (urine). Microcrystals form and attach to the urinary mucosa (most commonly to the end of the collecting duct). There stones gradually increase in size over time.

There are several risk factors for development of renal stones and they include hypercalciuria, hyperuricosuria, hypocitraturia (rather than hypercitraturia), high dietary protein intake and low intake of fluids (water). Urinary citrate helps to keep calcium in the solution and diminishes the likelihood for stone development.

Other risk factors are prior history of calcium nephrolithiasis, family history, increased enteric oxalate absorption (short bowel syndrome), urinary tract infection, hypertension, vasectomy and therapy with sulfadiazine and triamterene.

Educational objective: Review different imaging methods for identification of renal calculi.

Diagnosis of urolithiasis is strongly suspected from the clinical presentation. Tests used for confirmation of diagnosis include plain abdominal film, renal ultrasonography, intravenous pyelography and CT scanning.

Abdominal plain film identifies most radio opaque stones (calcium, struvite and cystine) but will miss radiolucent ones (urate) or small stones (especially if they overlay bony structures).

Intravenous pyelography is used in most cases and is relatively safe, despite use of the contrast. However, CT scanning may soon replace it as first used imaging modality.

Ultrasonography is the method of choice for patients who want to avoid radiation exposure. It has about equal sensitivity and specificity as plain abdominal film (64 and 100%). Machines with

Doppler capabilities improve sensitivity, but are cumbersome for patients and are heavily operator dependent. CT scanning has become a gold standard in recent years and is able equally well to distinguish radiolucent and opaque stones.