CLINICAL REVIEW Assessment and management of non-visible haematuria in primary care

Many clinicians are not sure what constitutes clinically relevant haematuria; they are also unsure about when patients with haematuria should be referred for specialist assessment and whether they should be referred to a urologist, nephrologist, or both. In 2006 the National Institute for Health Research, Health Technology Assessment (NIHR HTA) commissioned a systematic review of the evidence for the investigation of microscopic haematuria, with a view to developing an algorithm for assessing patients in primary care. They concluded that, “Given the paucity of evidence . . . it is not possible to derive an algorithm of the diagnostic pathway for haematuria that would be solely supported by existing evidence.” None the less, the investigation of microscopic haematuria is important because serious underlying conditions are present in a proportion of patients. In the absence of definitive evidence, guidelines based on consensus agreement and expert opinion wouldbe useful andhavebeenproposed. However, the terminology and definitions used have not been standardised, so the appropriate baseline assessment of patients is still unclear. In this review, we discuss the rationale for introducing the terms “visible haematuria” and “non-visible haematuria” (symptomatic and asymptomatic) (box 1). The figure shows an algorithm for the assessment of patients with nonvisible haematuria. What causes non-visible haematuria? Thepresenceof non-visible blood in theurine canhave a transientor spurious cause; if it persists itmay indicate underlying pathology.