Exertional hematuria: definition, epidemiology, diagnostic and clinical considerations

Exertional hematuria can be considered a subcategory of exercise-induced hematuria, characterized by painless appearance of erythrocytes in urine after recent physical exercise, not directly attributable to external traumatic injuries to the genitourinary system, and spontaneously resolving with rest. Although its frequency has enormous heterogeneity, depending on the athlete population, duration and intensity of exercise, technique used for identifying or quantifying hematuria and relative diagnostic thresholds, what clearly emerges from the scientific literature is that a certain degree of hematuria is commonplace after non-contact sports, especially running. This exertional hematuria, which appears self-limiting, may be attributable to some frequently concomitant causes, involving organs of the genitourinary system, and mostly encompassing bladder or urethral injuries. Renal injuries caused by internal movements, vascular spasm and ischemia are also potential causes of increased glomerular permeability to erythrocytes, whilst the presence of preexisting genitourinary diseases cannot be ruled out, especially when post-exercise hematuria is recurrent or endures. Therefore, whenever hematuria is observed in a random urine specimen, recent sports performance (especially running) should be investigated and urinalyses scheduled for the following days. When no temporal association of hematuria with exercise can be found, when genitourinary traumas have been excluded or hematuria persists for >72 h, specific diagnostic investigations should be planned to identify possible genitourinary diseases.

Haematuria in Sport: A Review

CONTEXT

Haematuria is a common urological presentation associated with patient anxiety and clinically relevant underlying pathology. However, the prevalence and pathophysiology of haematuria following sporting exercise is less well documented.

OBJECTIVES

This review paper seeks to clarify the prevalence of microscopic and macroscopic haematuria in association with sporting exercise reported in the literature, and the pathophysiology behind it. We review the relation of haematuria to injury to the urinary tract in sport, as well as the incidence of underlying disease, urological and incidental, following investigation for exercise-induced haematuria.

EVIDENCE ACQUISITION

A non-systematic literature review was conducted of articles and studies using the Pubmed database. Articles were selected with preference for the highest level of evidence available, with relevant data extracted, analysed, and summarised. Supplementary information was collected by cross-referencing the reference lists.

EVIDENCE SYNTHESIS

Multiple studies have shown that clinically significant haematuria is common after exercise. Physiological changes occurring during exercise result in increased glomerular permeability and microscopic haematuria in up to 95% of cases. The degree of haematuria is related to the intensity of the exercise. However, participating in contact sports increases the risk of macroscopic haematuria. Red cell haemolysis and rhabdomyolysis also play a role in urine discolouration following exercise and can be present in 30%. Haematuria following exercise-related trauma is regarded an important indication for further urological investigation. Haematuria may be absent in 44% of cases of urological injury. Renal trauma accounts for 80% of urological trauma, with 30% of these being due to sporting activity. Incidental findings on computed tomography for haematuria are common, with 50% showing positive extraurinary findings. Incidental malignancy, however, is rare.

CONCLUSIONS

Haematuria is common following exercise and results from physiological changes and contact-related trauma to the urinary tract. All cases of haematuria should be investigated as underlying trauma and extraurinary disease are common incidental findings on investigation.

PATIENT SUMMARY

Blood in the urine following exercise is a common phenomenon and occurs due to vascular responses to sports and trauma as well as blood and muscle cell breakdown. Although it may not be present in all cases of trauma, blood in the urine should be investigated due to the risk of discovering underlying injury to the urinary tract and other incidental findings.