A 62 year old caucasian male goes to the
emergency room for intense lower abdominal pain
associated with inability to urinate.
Physical examination shows
intense lower abdominal pain.
Rectal examination reveals an enlarged,
smooth and symmetric prostate.
The emergency room team fails to pass a foley
catheter through the urethra and the urology team
decides to place a suprapubic catheter to drain
the urine and relieve the patient's symptoms.
An ultrasound shows dilation of the
collecting system in both kidneys.
Laboratory results reveal an elevated
serum creatinine of (1.6 mg/dL)
and an estimated glomerular filtration
or eGFR of 50 (mL/min/1.73m2)
Three weeks after this acute event, the patient
visits the urology team for a follow up in clinic,
which he claims that time to be having close
to normal urination, however it is found
that the patient's serum creatinine
is 1.5 (mg/dL), persistently elevated.
What renal gross findings correlates
with this patient's condition?
Answer choice (A) - thin cortical rim
Answer choice (B) - ureteropelvic
Answer choice (C) - enlarged
kidneys with bosselated surface
Answer choice (D) -
pale cortical deposits
or answer choice (E)
- granular surface
Now take a moment to come to the answer by
yourself before we go through it together.
Okay let's jump in to this question.
Let's discuss the
Now this is a pathology question.
The patient obviously has some kind of a condition
in which he has obstruction of urinary outlow,
hence pathology and infects the kidneys.
So this is Renal-Path.
Now this is a 2-step question.
We first have to come to a diagnosis then we need to
determine what gross macroscopic pathological finding
would we expect to be
associated with that condition.
And the stem is absolutely required to know both
the history and also the laboratory findings.
Now let's walk through this question together.
The first thing we need to do is
determine the likely diagnosis.
Now this patient presenting
with acute urinary obstruction
which is secondary to benign
prostatic hyperplasia or BPH.
Now the presence of an elevated creatinine 3
weeks after the relief of the acute obstruction
is actually suggestive of renal damage to the chronic
urinary outflow obstruction secondary to the BPH.
So before we determine the cause or the etiology of what
kind of microscopic finding we would see in the kidneys,
let's go through the image to discuss BPH first
to help us better understand the condition
to then we can better think and figure out why
and what type of kidney damage we would expect.
Now looking at the image, on the left side
we see the image of a normal prostate.
the circle there is the bladder, and
the urine's going through the bladder
and going through the urethra then
and the prostate sitting around it.
Now on our right side, we see an episode of benign
prostatic enlargement or benign prostatic hypertrophy.
Now in this case, we actually
see again the bladder
but urine there it's kind of coming
and going back at a nice outflow,
and the prostate's enlarged and causing compression
of the urethra and inhibiting outflow.
And this is what we see in the case
of benign prostatic hyperplasia in which
the prostate is enlarged and causing compression
of the urethra and obstructing urinary outflow.
Thus if you were to obstruct your urinary outflow, you
will then have obstruction up to the ureters at the kidney
and cause a back elevator
pressure within the kidney.
And thus, going back to our
walkthrough this question,
the step 2 is to determine the likely
macroscopic renal changes associated with BPH.
Well think that chronic urinary
outflow obstruction like we said,
results in urinary tract dilation
and also then, renal damage.
This is called obstructive nephropathy
- vey important to understand.
Now, very very high-yield is that obstructive
nephropathy is characterized by progressive atrophy
of the renal cortex which will then lead
to a thin cortical rim of the kidney.
Now this has to make sense in your mind,
because what's very important to recall here
is that it is the renal cortex that contains the
nephrons, and thus if you have increased pressure
within the middle of the kidney and you push pressure
on to the cortex and you thin the cortex out,
you're damaging where the nephrons are and essentially
you're having that key renal function of urinary production
and if you damage that you're gonna
have an elevated creatinine level.
So in this case, the answer choice is
answer choice (A) - thin cortical rim.
Now let's discuss some high-yield facts
regarding BPH and obstructive nephropathy.
Now BPH is common in men after middle age and it
presents in around half of men aged about 50 years old.
BPH commonly presents with symptoms related
to increased frequency of urination,
typically a patient who has to keep
getting up at night to urinate
and difficulty initiating urination
or noticing a weak urinary stream.
Now BPH can present as acute urinary obstruction
with abdominal pain and urinary retention
as it did in this question stem.
Now let's discuss obstructive nephropathy.
Now BPH can result in obstructive nephropathy
due to chronic urinary outflow obstruction.
Now obstructive nephropathy is characterized
by atrophy of the renal cortex.
And the typical macroscopic finding of obstructive
nephropathy is thinning of the cortical rim of the kidney
which is important because the nephrons are located
in the cortex and the impairment of the nephrons
will cause an impairment of renal function
and an elevation in creatinine levels.