Blood in the urine may be seen with the naked eye (variously described as macroscopic, frank, or gross haematuria), or may be detected on urine dipstick (dipstick haematuria) or by microscopic examination of urine (microscopic haematuria, defined as the presence of >3 red blood cells per high power microscopic
1. PRESENTING SYMPTOMS OF UROLOGICAL EMERGENCIES 3
field). Just 5mL of blood in 1 L of urine is visible with the naked eye. Dipstick tests for blood in the urine test for haemoglobin rather than intact red blood cells. A cause for the haematuria cannot be found in a substantial proportion of patients despite investigations in the form of flexible cystoscopy, renal ultrasonography, and intravenous urography (IVU) (no cause for the haematuria is found in approximately 50% of patients with macroscopic haematuria and 60% to 70% of patients with microscopic haematuria; Khadra et al. 2000).
Haematuria has nephrological (medical) or urological (surgical) causes. Medical causes are glomerular and nonglomerular, for example, blood dyscrasias, interstitial nephritis, and reno-vascular disease. Glomerular haematuria results in dysmorphic erythrocytes (distorted during their passage through the glomerulus), red blood cell casts, and proteinuria, while non-glomerular haematuria (bleeding from a site in the nephron distal to the glomerulus) results in circular erythrocytes, the absence of erythrocyte casts, and the absence of proteinuria.
Surgical/urological nonglomerular causes include renal tumours, urothelial tumours (bladder, ureteric, renal collecting system), prostate cancer, bleeding from vascular benign prosta-tic enlargement, trauma, renal or ureteric stones, and urinary tract infection. Haematuria in these situations is usually characterised by circular erythrocytes and absence of proteinuria and casts.
Haematuria can be painless or painful. It can occur at the beginning of the urinary stream, at the end of the urinary stream, or be present throughout the stream. Haematuria at the beginning of the stream may indicate urethral or prostatic pathology. Haematuria at the end of the stream may indicate prostatic urethra or bladder neck pathology and that present throughout the stream of urine may indicate renal or bladder pathology.