Hematuria: Evaluation and Management

Introduction

Hematuria is the presence of red blood cells in the urine and can be visible to the naked eye (macroscopic), detectable with microscopic analysis or found by dipstick testing of urine. Around 40% of patients with hematuria have a significant underlying cause regardless of the quantity of blood in the urine. As the presence of hematuria is common and there are often no clues as to the underlying cause, this condition comprises a large amount of the urological workload and should be regarded as a manifestation of urological malignancy until proven otherwise.1 While it is recognized that the contemporary urological approach for the investigation of hematuria may not always be evidence-based medicine,1 there are numerous high-quality studies confirming the prevalence of disease within patients with this condition.

Classification of Hematuria

The simplest classification of hematuria is according to the extent of blood.

Macroscopic Hematuria

Macroscopic hematuria is the presence of visible blood in the urine and is a common cause of urological referral. Around 2.5% of the community

has macroscopic hematuria2 and the incidence of underlying cancer has been reported as between 22% and 24.2%.2,3 The risk of cancer is greater with macroscopic than microscopic hematuria and rises with advancing patient age. Macroscopic hematuria is the commonest presenting symptom for patients with urothelial cell carcinoma (UCC)3 and investigation of this symptom is considered mandatory in all patients.4

Microscopic Hematuria

Microscopic hematuria is the presence of red blood cells (RBCs) within the urine that are visible only with microscopic analysis of centrifuged urinary sediments. Asymptomatic hematuria is common and has a reported prevalence between 0.19% and 21%.5-7 For example, in British males, the prevalence of microscopic hematuria is around 2.5%.8 This frequency varies according to the population studied and the definition of hematuria used. The definition of abnormal urinary RBCs is contentious.Traditionally,the upper limit of normal urinary RBC has been between three and five RBCs per high power field (RBC/ hpf).5,9,10 The American Urological Association has recently defined microscopic hematuria as ³3 RBCs/hpf in the urinary sediment from two of three properly collected specimens.6,11 However, malignancies can be detected in patients with fewer than 3 RBCs/hpf, and therefore, some authors suggest investigating all patients with