Материал: Oxford American Handbook of Urology ( PDFDrive )

2CHAPTER 1 Preliminary investigation

Hematuria I: definition and types

Definition

Hematuria is the presence of blood in the urine.

Macroscopic (gross) hematuria is visible to the naked eye.

Microscopic or dipstick hematuria is when blood is identified by urine microscopy or dipstick testing, either in association with other urological symptoms (symptomatic microscopic hematuria) or during a routine medical examination (asymptomatic microscopic hematuria).

Microscopic hematuria is generally defined as 3 or more red blood cells (RBCs) per high-power field on a centrifuged specimen confirmed on 2 of 3 properly collected specimens.1,2

Urine dipsticks test for heme test for hemoglobin and myoglobin in the urine. The peroxidase-like activity of heme is used to catalyze reactions that produce colored compounds ranging from orange to green and dark blue. Dipsticks have a sensitivity of 90%, detecting 5 RBC/microliter. Confirm the presence of RBCs on a dipstick with microscopic exam to rule out a false positive.

•False positive urine dipstick: menstrual or dysfunctional uterine bleeding contamination, or the presence of myoglobinuria, free hemoglobin (e.g., transfusion reaction), bacterial peroxidases, povidone, hypochlorite

•False negative urine dipstick (rare): in the presence of reducing agents (e.g., ascorbic acid prevents the reagent strip oxidation reaction)

Is microscopic or dipstick hematuria abnormal?

A few RBCs can be found in the urine of normal people. The upper limit of normal for RBC excretion is 1 million/24 hours (as seen in healthy medical students). In healthy male soldiers undergoing yearly urine examination over a 12-year period, 40% had microscopic hematuria on at least 1 occasion and 15% on 2 or more occasions. Transient microscopic hematuria may occur following rigorous exercise or sexual intercourse.

A catheterized urinary specimen may be needed if a voided specimen cannot be reliably obtained (e.g., vaginal contamination, obesity, men with nonretractile foreskin [phimosis]).

Because the presence of RBCs in the urine is normal, a substantial proportion of patients with microscopic and dipstick hematuria and even macroscopic hematuria will have normal hematuria investigations (i.e., no abnormality is found). No abnormality is found in approximately 50% of subjects with gross hematuria and 70% with microscopic hematuria, despite full conventional urological investigation (urine cytology, cystoscopy, upper tract imaging).2

1 Grossfeld GD, Litwin MS, Wolf JS, et al. (2001). Evaluation of asymptomatic microscopic hematuria in adults: the American Urological Association best practice policy—part I: definition, detection, prevalence, and etiology. Urology 57:599–603.

2 Khadra MH, Pickard RS, Charlton M, et al. (2000). A prospective analysis of 1930 patients with hematuria to evaluate current diagnostic practice. J Urol 163:524–527.

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4CHAPTER 1 Preliminary investigation

Hematuria II: causes and investigation

Any degree of confirmed hematuria should be evaluated, as it may be a sign of serious renal or urological disease, including malignancy (up to 20%). Gross hematuria is 5 times more likely to indicate a serious urological problem than is microscopic hematuria.

Common causes of hematuria

Although there is considerable overlap, hematuria in the clinical setting can be most broadly classified into surgical (urological) and medical causes, to help facilitate evaluation and management. Presence of white blood cells (WBCs) or bacteria, protein, red cell casts, or elevated serum creatine (Cr) and age of the patient may also be used to determine the cause.

Surgical (urological)

•Cancer: urothelial carcinoma or squamous cell carcinoma of the urethra, bladder, ureter, or renal pelvis; renal cell carcinoma; prostate cancer; other less common tumor types (sarcoma, adenocarcinoma)

•Stones (urolithiasis): kidney, renal pelvis, ureter, bladder

•Infection: pyelonephritis, cystitis, prostatitis, urethritis caused by agents such as bacterial, mycobacterial (TB), parasitic (schistosomiasis), fungal (Candida)

•Inflammation: cyclophosphamide cystitis, interstitial cystitis, radiation cystitis

•Trauma (blunt and penetrating): kidney, bladder, urethra (e.g., traumatic catheterization), pelvic fracture with urethral disruption

•Renal cystic disease: e.g., medullary sponge kidney

•Congenital abnormalities: vesicoureteral reflux, posterior urethral valves, ureteropelvic junction obstruction

Other urological causes include benign prostatic hyperpasia (BPH) (the large, vascular prostate), urethral stricture, fistula, urethral diverticulum, cystocele, recent surgical intervention, flank pain hematuria syndrome, and vascular malformations.

Medical (nephrological)

Medical causes of hematuria are more likely in children and young adults and if it is associated with proteinuria, elevated creatinine, or dysmorphic red cells/RBC casts. Glomerulonephritis is responsible for 30% of all cases of pediatric hematuria.

Renal parenchymal disease occurs with IgA nephropathy (Berger disease), postinfectious glomerulonephritis, and, less commonly, membranoproliferative glomerulonephritis, Henoch–Schönlein purpura, vasculitis, Alport syndrome, thin basement membrane disease, and Fabry disease.

Other medical causes include coagulation disorders (congenital, such as hemophilia) or anticoagulation therapy; sickle cell trait or disease; renal papillary necrosis; hypercalcuria; and vascular disease (e.g., emboli to the kidney with infarction and hematuria).

HEMATURIA II: CAUSES AND INVESTIGATION 5

Urological investigation of hematuria

In patients without evidence suggestive of medical renal disease, conventional urological investigation involves urine culture (if symptoms suggest urinary infection), urine cytology, cystoscopy, and upper tract imaging. Anticoagulation or aspirin use should never be automatically assumed to be the cause of hematuria. In these patients, malignancy can be seen in up to 24% and any hematuria should be evaluated.1

Patients with documented urinary tract infection (UTI) should be treated appropriately, and the urinalysis repeated approximately 4–6 weeks after treatment. If the hematuria resolves with treatment, no further evaluation is usually needed.2

In low-risk patients (<40 years without gross hematuria, no smoking history, no chemical exposure [i.e., benzenes or aromatic amines], no previous cyclophosphamide treatment, no irritative voiding complaints, no pelvic radiation, or no urological disease history), initial upper tract imaging is indicated, with further evaluation based on clinical findings.

In patients with high risk factors (high risk for urothelial carcinoma anywhere in the urinary tract), compete evaluation is indicated given the greater risk of malignancy.

Diagnostic cystoscopy

Typically this is carried out using a flexible, fiber-optic cystoscope in the outpatient setting with intraurethral lidocaine anesthesia.

•If radiological investigation demonstrates a lesion suggesting a urothelial carcinoma such as a bladder cancer, one may consider foregoing the flexible cystoscopy and proceed immediately to rigid cystoscopy and biopsy under anesthesia (transurethral resection of bladder tumor [TURBT]).

•Upper tract filling (renal pelvis, ureter) defects may also represent urothelial carcinoma or stones. Further intraoperative evaluation with retrograde pyelograms and ureteroscopy can be both diagnostic and therapeutic. However, the bladder must still be evaluated carefully with cystoscopy.

Should cystoscopy be performed in patients with asymptomatic microscopic hematuria?

The American Urological Association’s (AUA’s) Best Practice Policy on Asymptomatic Microscopic Hematuria recommends cystoscopy in all highrisk patients with microscopic hematuria (see risk factors on previous page).3 In asymptomatic, low-risk patients <40 years of age, it states that “it may be appropriate to defer cystoscopy,” but if this is done, urine should be sent for cytology.

1 Avidor Y, Nadu A, Matzkin H (2000). Clinical significance of gross hematuria and its evaluation in patients receiving anticoagulant and aspirin treatment. Urology 55(1):22–24.

2 Mariani AJ (1998). The evaluation of adult hematuria: a clinical update. In AUA Update Series 1998; Vol. XVII, lesson 24, pp. 185–192. Houston: AUA Office of Education.

3 Grossfeld GD (2001). Evaluation of asymptomatic microscopic hematuria in adults: the American Urological Association Best Practise Policy-Part II: patient evaluation, cytology, voided markers, imaging, cystoscopy, nephrology evaluation and follow-up. Urology 57:604–610.