Haematuria refers to the presence of red blood cells in the urine. The source of bleeding may be anywhere along the genitourinary tract. When visible to the naked eye, it is termed ‘gross’. When evident only with magnification, it is termed ‘microscopic’.
The presence of blood in the urine, regardless of the quantity, warrants further investigation. A small percentage of people may lose several red blood cells per high-power field via ‘leaking’ glomeruli. Likewise, many benign conditions and anti-coagulant use may cause haematuria. No matter the circumstance, however, haematuria may be the only sign of serious underlying pathology and should not be deemed acceptable until a thorough evaluation has been completed.
Patient history is a key in identifying the cause of bleeding. Haematuria can be total throughout the urine stream, and has a source from the bladder or higher in the urinary tract. It can be terminal, or only at the end of voiding, and usually originates from the prostate in males. Initial haematuria, which clears as voiding continues, often originates in the urethra, prostate, or external genitalia. A history of trauma or other symptoms, such as loin pain or dysuria, can also help identify the cause. Likewise, other items in the history may point to a diagnosis. These may include smoking or a family history of urologic disease to name a few. Microscopic haematuria is usually asymptomatic and found by urinalysis alone.
A proper evaluation for haematuria begins with a thorough physical examination. The loins should be assessed for haematoma and palpated to elicit costovertebral angle tenderness. External genitalia in both males and females should be inspected for lesions. A bimanual examination in the female patient and assessment of the prostate in the male by rectal examination completes the examination.
Urine dipstick indicators are frequently used to identify the presence of blood. Unfortunately, false positives can occur with these colour indicators by the presence of items such as myoglobin or povidone iodine. Therefore, microscopy following centrifugation is the best tool to analyse the urine. In addition to the character and number of red blood cells seen, white blood cells, bacteria, yeast, and crystals can help make a diagnosis.
Urine cytology is another helpful tool for identifying malignant cells in the urine. Dysplastic, suspicious, and overtly malignant cells are frequently seen, with highgrade urothelial cancers and carcinoma in situ, but not with lower-grade lesions.
Many new urine markers are currently under investigation and may prove to be more useful than cytology in identifying urothelial carcinoma.
Serum electrolytes, creatinine, haemoglobin, and white cell count provide objective insight into the degree of haematuria, renal function, and the presence of infection. If calculus disease is suspected, serum uric acid and calcium are also indicated. Prostate specific antigen (PSA) is useful if there is suspicion of prostate cancer.
Aetiology and diagnosis
Many authorities accept between two and five red blood cells per high-power field as normal filtration through the glomerular basement membrane. A host of glomerulopathies also allow increased loss of erythrocytes into the urine (Representative glomerular diseases). Nephrogenic causes of haematuria should be more actively pursued when associated with a negative urologic evaluation, proteinuria, and hypertension. Dysmorphic red blood cells and red cell casts on urinalysis support the diagnosis of nephrogenic haematuria. If glomerular disease is suspected, creatinine clearance and 24-hour urine measurements of protein excretion should be obtained in addition to the serum chemistry discussed earlier.
Upper urinary tract
The upper urinary tract includes the kidneys and ureters. Sources of haematuria in these structures are listed in General causes of haematuria. They can include neoplasms (renal cell carcinoma, urothelial carcinoma), calculi, infection, and vascular malformations.
Renal ultrasound is an adequate screening modality for the upper tracts. It can identify a renal mass, stones, and give supporting evidence for obstruction (hydronephrosis). Renal ultrasound clearly differentiates solid from cystic renal lesions. Ultrasound is also useful when radiation exposure must be limited as in, for example, the pregnant patient. Non-contrast CT scan of the abdomen and pelvis is also useful as a screening study for haematuria. It can demonstrate almost every type of urinary calculus (stones from protease inhibitors, such as indinavir, are invisible to all imaging modalities) and renal masses and identify hydronephrosis. CT scan has the added benefit of evaluating structures outside the urinary tract. A triple-phase CT scan, one taken before contrast, with contrast, and following contrast provides complete evaluation of the upper urinary tracts. The contrast image, or nephrogram phase, evaluates and characterizes suspicious renal lesions. The delayed image, or pyelogram phase, evaluates the renal collecting system and ureters for obstruction and filling defects (which could represent urothelial tumours). Measuring the attenuation of suspicious renal lesions, in Hounsfields units, aids in the diagnosis of neoplasms.
The intravenous pyelogram (IVP) is a valuable imaging study to evaluate the upper urinary tract. It clearly demonstrates the presence of and level of an obstruction. Although the IVP is often used for identifying filling defects throughout the collecting system, it can also demonstrate the presence of and the level of an obstruction. Causes of filling defects include blood clots, stones, tumours, sloughed renal papilla, and infectious debris including fungus balls. The IVP is also useful for visualizing the anatomy of the renal units.
Both the contrasted CT scan and the IVP require injection of intravenous contrast medium that can cause acute renal failure and should not be used in patients with impaired renal function (creatinine > 170µmol/L). The contrast medium can also incite anaphylaxis in allergic individuals. A steroid preparation can be given prior to the study in those with minor allergic reactions, but contrast should be avoided in anyone with a more pronounced reaction. MRI with and without gallidinium is an alternative to these studies. Like the CT scan, it can identify and characterize obstruction, filling defects, and renal lesions, but avoids the use of contrast.
Retrograde ureteropyelogram, or direct visual injection of contrast into the ureteral orifice during cystoscopy, is another means to evaluate the upper urinary tract. It is more invasive, but can be used in cases of contrast allergy. Retrograde ureteropyelograms are quite useful when an obstruction limits visualisation of the lower segment of a ureter. Ureteroscopy allows direct visualisation of the ureter and renal collecting system. In addition, biopsies of suspicious areas can be taken through the ureteroscope.
Lower urinary tract
The lower urinary tract includes the bladder and urethra. It also includes the prostate in males. Some causes of haematuria in these structures are listed in General causes of haematuria. The only way to completely visualise the bladder and urethral mucosa is with cystourethroscopy. It involves placing a lighted endoscope directly through the urethra and into the bladder for inspection. Cystourethroscopy can be performed under local anaesthesia, but spinal or general anaesthesia is often required if biopsies or other intervention is to be performed.
Occasionally, conditions of the male and female genitalia can cause haematuria and must be considered when all other investigations are normal. A repeat urine specimen or catheterised specimen is recommended in menstruating women to exclude contamination.