HEMATURIA HAEMATURIA

Hematuria : the presence of blood in the urine.
Macroscopic? (gross) hematuria: the patient has seen blood.
Microscopic or dipstick hematuria: blood identified by urine microscopy or by dipstick testing, either in association with other urological symptoms (symptomatic microscopic hematuria?) or during a routine medical examination (e.g. for insurance purposes) (asymptomatic microscopic hematuria?).
Microscopic hematuria has been variably defined as 3 or more, 5 or more, or 10 or more red blood cells (RBCs) per high-power field.
Urine dipsticks test for heme (i.e. they test for the presence of haemoglobin and myoglobin in urine). Heme catalyses the oxidation of orthotolidine by an organic peroxidase, producing a blue coloured compound. Dipsticks are capable of detecting the presence of haemoglobin from 1 or 2 RBCs.
False +ve urine dipstick: occurs in the presence of myoglobinuria, bacterial peroxidases, povidone, hypochlorite.
False -ve urine dipstick (rare): occurs in the presence of reducing agents (e.g. ascorbic acid prevents the oxidation of orthotolidine). 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 per 24h (as seen in healthy medical students). In healthy male soldiers undergoing yearly urine examination over a 12-yr 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, sexual intercourse, or from menstrual contamination.
The fact that the presence of RBCs in the urine is normal explains why 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 macroscopic hematuria and 70% with microscopic hematuria, despite full conventional urological investigation (urine cytology, cystoscopy, renal ultrasonography, and IVU).1
causes and investigation
Urological causes of hematuria
Cancer: bladder (TCC, SCC), kidney (adenocarcinoma), renal pelvis and ureter (TCC), prostate
Stones: kidney, ureteric, bladder
Infection: bacterial, mycobacterial (TB), parasitic (schistosomiasis), infective urethritis
Inflammation: cyclophosphamide cystitis, interstitial cystitis
Trauma: kidney, bladder, urethra (e.g. traumatic catheterization), pelvic fracture causing urethral rupture
Renal cystic disease (e.g. medullary sponge kidney)
Other urological causes: BPH (the large, vascular prostate), loin pain hematuria syndrome, vascular malformations
Nephrological causes of hematuria tend to occur in children or young adults and include, commonly, IgA nephropathy, postinfectious glomerulonephritis; less commonly, membranoproliferative glomerulonephritis, Henoch Schönlein purpura, vasculitis, Alport's syndrome, thin basement membrane disease, Fabry's disease, etc.
Other medical? causes of hematuria include coagulation disorders congenital (e.g. haemophilia), anticoagulation therapy (e.g. warfarin); sickle cell trait or disease; renal papillary necrosis; vascular disease (e.g. emboli to the kidney cause infarction and hematuria).
Nephrological causes are more likely in the following situations: children and young adults; proteinuria; red blood cell casts.

Urological investigation of hematuria
Conventional urological investigation involves urine culture (where, on the basis of associated cystitis? symptoms urinary infection is suspected), urine cytology, cystoscopy, renal ultrasonography, and IVU.

Diagnostic cystoscopy
Nowadays this is carried out using a flexible, fibreoptic cystoscope, unless radiological investigation demonstrates a bladder cancer, in which case one may forego the flexible cystoscopy and proceed immediately to rigid cystoscopy and biopsy under anaesthetic (transurethral resection of bladder tumour TURBT).

Should cystoscopy be performed in patients with asymptomatic microscopic hematuria?
The AUA's Best Practice Policy on Asymptomatic Microscopic Hematuria recommends cystoscopy in all high-risk patients (high risk for development of TCC) with microscopic hematuria (see risk factors below).2 In asymptomatic, low-risk patients <40 it states that it may be appropriate to defer cystoscopy?, but if this is done, urine should be sent for cytology. However, the AUA also states that the decision as to when to proceed with cystoscopy in low-risk patients with persistent microscopic hematuria must be made on an individual basis after a careful discussion between the patient and physician?. It is our policy to inform such patients that the likelihood of finding a bladder cancer is low, but nevertheless we recommend flexible cystoscopy. The patient then makes a decision as to whether or not to proceed with cystocopy based on their interpretation of low risk?.2

If no cause for hematuria is found (microscopic or macroscopic) is further investigation necessary?
Some say yes, quoting studies that show serious disease can be identified in a small number of patients where, in addition, retrograde ureterography, endoscopic examination of the ureters and renal pelvis (ureteroscopy), contrast CT, and renal angiography were done. Others say no, citing the absence of development of overt urological cancer during 2 4 year follow-up in patients originally presenting with microscopic or macroscopic hematuria (though without further investigations).3
When urine cytology, cystoscopy, renal US, and IVU are all normal, we perform CT scanning of the kidneys and ureters and retrograde ureterography in:
patients at high risk for TCC*
where microscopic or dipstick hematuria persists at 3 months
where macroscopic hematuria persists