© The Canadian Journal of Urology™; 19(Supplement 1); October 2012
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What is significant hematuria for the primary care physician?
Pre hydration is also beneficial, particularly in
children. The dipsticks should not have passed their
expiry date, and they should have been stored at the
correct temperature. To perform the test, the dipstick
should be quickly and completely immersed into the
urine specimen, and then it should be tapped on its
edge to remove excess urine and to reduce the mixing
of reagents from different test pads on the dipstick.
If the patient has microscopic hematuria, then the
urine dipstick test will show a positive color reaction.
The physician should also look for significant urine
protein on the urine dipstick test, which may suggest
nephrologic disease.
When confronted with a convincing history of
gross hematuria and/or a positive dipstick result,
the physician should request a microscopic urinalysis
and ensure that the patient collects a urine specimen
after waiting at least 48 hours after menstruation,
vigorous exercise, or sexual activity. The physician
needs to pay attention to the number of RBCs and their
morphology, since thismay identify undiagnosed renal
conditions. The patient can be referred to a urologist
or a nephrologist, as needed, for further evaluation.
Ancillary studies
Patients with significant hematuria will need to be
referred to an appropriate specialist. Although such
specialists will be initiating their own work up, the
primary care physician should first order some basic
ancillary tests. Doing this will significantly facilitate
a timely assessment for their patients.
Laboratory investigations
Suggested laboratory investigations include blood
urea nitrogen (BUN), serum creatinine, and estimated
glomerular filtration rate (eGFR), which will indicate
the patient’s overall renal function. If tests show that a
patient’s renal function is compromised, this suggests
that he or she may need a nephrologic assessment, to
look for kidney impairment and for a non-urological
cause for the hematuria. Knowledge of a patient’s
renal status is helpful in selecting imaging modalities
during the patient work up process (as discussed later
in this article). Examination of blood coagulation
parameters (international normalized ratio [INR] and
partial thromboplastin time [PTT]) may help explain
the magnitude of the perceived hematuria and may
identify a coagulopathy that needs urgent correction.
Note, however, that a coagulopathy—whether it is
primary or a result of medical therapy—should not
be considered a sole cause for hematuria, so further
investigation is strongly advised.
8
A coagulopathy
may simply unmask underlying pathology more
quickly. In women of reproductive age, it may be
helpful to perform a serum beta-HCG test to rule out
pregnancy, since pregnancy would affect the selection
of imaging tests.
Urine cytology tests and determination of urine
markers (e.g., bladder tumor antigen [BTA] stat, and
nuclear matrix protein 22 [NMP-22]) should not be
part of a routine evaluation. In general, there are
large discrepancies in reports of the sensitivities and
specificities of these tests.
9
The only instances where it
may be reasonable to consider an ancillary urine test is
in a patient with significant hematuria and a previous
negative work up or a patient with risk factors for
bladder cancer or carcinoma in situ. However, this
can generally be left to the judgment of a urologist.
Imaging
Making didactic recommendations about appropriate
urinary tract imaging can be challenging. Compared
with laboratory testing, imaging studies are far more
costly and labor intensive, which can be a burden on
the healthcare system. In Canada, the remoteness of
some practice locations does not allow for easy access
to all imaging modalities. Moreover, there is very
little literature about comparative, controlled studies
of imaging in patients with hematuria.
Ultrasound:
The use of ultrasound is considered a less-
than-optimal choice for the investigation of hematuria.
Ultrasound is mainly limited to investigating the renal
parenchyma, and the sensitivity and specificity of
ultrasound varies widely.
10-12
In practice, ultrasound
is helpful for identifying large renal masses and
stones. Although it is not the best type of imaging
modality, ultrasound is still frequently used due to its
widespread availability and its safety relative to other
types of imaging. An intravenous urogram (IVU) may
be requested, to provide some detail about the upper
urinary tract anatomy, but is not commonly offered
by most imaging departments nowadays, especially
if computed tomography (CT) and CT urography is
available.
CT urography (CTU):
If it is available, CTU is the
preferred form of diagnostic imaging for patients with
hematuria. In noncomparative studies, CTU has the
highest degree of sensitivity and specificity.
13,14
It is
very rapid and can be performed in minutes when a
multiphasic CTmachine is used. Multiphasic imaging
will give excellent information on baseline densities,
which is important regarding urolithiasis. In addition,
other phases can identify renal parenchymal masses,
areas of trauma or scar, and filling defects within
the collecting system. A CT scan may also identify
other unusual causes of hematuria (e.g., renal artery
