© The Canadian Journal of Urology™; 19(Supplement 1); October 2012
Sing AND Singal
40
stenosis, abdominal aortic aneurysm) or may discover
incidental non-related pathology. Aside from cost,
drawbacks include radiation exposure, which can be
particularly significant in children and in undiagnosed
pregnancy. However, lower-dose protocols can be
devised to deal with this issue. Renal impairment is
another factor that may preclude this investigation
because of the nephrotoxicity of intravenous contrast
materials. AnN-acetyl cysteine protocol including pre-
hydrationmay be employed to counter nephrotoxicity
in selected patients, but it is advisable to do so in
consultation with a nephrologist. Contrast reactions
have been reported, and in very rare instances, death
has been attributed to contrast agents.
Magnetic resonance urography (MRU):
MRU may
be a suitable, though less effective imaging modality
in patients where CT urography is contraindicated.
MRU may be safer than CT urography, although
patients may have a nephrotoxic risk from the
gadolinium used in MR contrast studies. MRU is
contraindicated in patients with devices such as
pacemakers and aneurysmal clips. Moreover, MRU
protocols are subject to considerable variation making
interpretation of limited, comparative data difficult.
When considering non-comparative data, it appears
that MRU provides high sensitivity and specificity
imaging of renal parenchyma, but is not as useful
when imaging kidney stones or the collecting system.
15
The choice of an imaging modality depends on
several factors. Since ultrasound is widely available
and nontoxic, it is reasonable to order this imaging
test first. It is the authors’ opinion that CTU should
be ordered in patients with gross hematuria and
possibly also in patients with microscopic hematuria
who possess significant risk factors suggesting
genitourinary pathology. The patient should either
have no contraindication for the use of a contrast
agent with CTU, or have a contraindication that can
be appropriately managed. For example, N-acetyl
cysteine prophylaxis can be given to a patient who
has borderline renal function and few other medical
comorbidities. Decisions regarding the use of MRU
and retrograde pyelography can be delegated to a
urologist who will likely have direct access to these
resources.
Referringapatient toaurologist ornephrologist
Based on the preceding discussion, it seems quite
reasonable that primary care physicians should refer
all patients with significant hematuria to a urologist
or nephrologist. Some physicians may argue that
the rates of malignancy in younger patients (< 35
years of age) with hematuria are very low, so very
few malignancies would be found after referrals to
specialists following negative imaging tests. The
authors would argue that these patients compose a
much smaller proportion of patients with hematuria,
so the absolute number of referrals resulting in normal
findings is quite low. Moreover, imaging modalities
performed on patients can vary, so we believe that a
referral offers a more consistent patient evaluation,
which can only benefit patients in the long run.
Referral to a nephrologist is helpful when a
patient is found to have compromised renal function,
proteinuria, and RBC dysmorphia/RBC casts. The
latter may occur with concomitantly with other causes
of hematuria as well, so it is important to consider
involvement by urology as well.
To complete the patient’s urology work up,
cystoscopy may be considered. Cystoscopy is
recommended for all adult patients with gross
hematuria and significant risk factors. If a patient
presents with asymptomatic microscopic hematuria
and no risk factors, then cystoscopy should be done
if the patient is older than 35 or 40.
2
In children,
cystoscopy is best considered when gross hematuria
is present. There is very low yield with cystoscopy
in pediatric microscopic hematuria. Even if no
malignancy is found, the urologist may discover other
findings that could benefit the patient. For example,
a young man with hematuria and lower urinary tract
symptoms (LUTS) may be found to have a urethral
stricture. In this case, cystoscopy would lead to a very
treatable diagnosis and would result in a significant
impact on quality of life.
Ongoing follow up
Even with a negative work up, patients are still
concerned that their hematuria may be persistent and
may evolve into pathology if left unchecked. The
literature reports that 1%-3%of patients with a negative
work up can develop a malignancy within 3 years.
5
As a result, it is reassuring to form a strategy that
deals with these concerns. The American Urological
Association best policy panel recommends that primary
care physicians check for gross hematuria, newurinary
symptoms, and positive cytology semi-annually for 3
years. If all is negative at that time, follow up may be
discontinued. If not, then repeat evaluation should be
performed.
Disclosure
The authors have no potential conflict of interest.
