Today we'll talk about further
disorders of the large bowel.
So we'll begin with a case
We have a 78-year-old man who
was hospitalized for pneumonia.
He has a history of coronary artery
disease and peripheral artery disease
with chronic ulcers on
his left lateral ankle.
On hospital day 2, he suddenly develops
severe abdominal pain and watery diarrhea.
Vitals are notable for an irregularly irregular
pulse of 130 and a blood pressure of 92/55
On abdominal exam, he has mild tenderness in
the lower quadrants without rebound tenderness.
His rectal exam shows light brown stool.
Labs show a leukocyte
count of 11,000 and lactate of 6
EKG shows atrial fibrillation and a
stool PCR for C. difficile is negative.
What is the most likely diagnosis?
So let's go through
some key clinical features.
He has a history of known
and he's now presenting with sudden
onset severe abdominal pain with diarrhea.
He does have a history of atrial fibrillation as
by his physical exam and confirmed on EKG.
And interestingly, although he
describes severe abdominal pain,
on exam, he just has mild tenderness.
This is described as abdominal pain
out of proportion to his exam findings.
And he has a high white count and an elevated
lactate which are both somewhat concerning.
Lastly, he has a negative C.difficile PCR.
This is helpful because in a patient coming in with
abdominal pain and diarrhea who's been hospitalized,
you would worry about C. difficile infection.
But a negative test is reassuring.
So before we answer that question, let's look at
some key clinical clues and put them all together.
Let's think, what condition is associated with sudden
onset abdominal pain out of proportion to physical exam
and a history of atrial fibrillation
with atherosclerotic disease.
So you might be thinking
of mesenteric ischemia
This is when you have a decline
which can be either acute or chronic
in your arterial or venous
intestinal blood flow.
So, we'll have to recall our
anatomy of blood flow to the colon
Recall that the aorta is the largest vessel
in your body that supplies blood elsewhere.
You have your superior mesenteric artery or
the SMA that supplies a large portion of the colon
and the inferior mesenteric artery or the
IMA which supplies the rest of the colon.
So mesenteric ischemia
can either be acute or chronic.
When it is acute, it is a vascular
emergency with a very high mortality rate
It usually results from an acute
embolism or an arterial thrombosis
but there are other
causes we'll go into next.
It can also be chronic which is
a more long standing process
commonly due to underlying
So let's talk in detail about
acute mesenteric ischemia.
It results from an acute drop
in the perfusion to the intestine
and as we mentioned before has
a very high mortality rate of around 60%
It can be from an embolism, a
thrombosis or a non-occlusive ischemia
and patients will present with sudden
abdominal pain out of proportion to physical exam
They may have anorexia or loss of appetite,
vomiting or peritonitis in various severe cases.
The diagnosis is made by angiography.
This can be either through CT
angiography or interventional angiography.
Here on the right, you see an
example of CT angiography
In this case, you can see a cut-off of the blood flow
in the mid portion of the superior mesenteric artery.
This is likely from an
occlusive embolism in this case.
So treatment, is with
primarily supportive therapy,
so giving IV fluids, avoiding medications that
will cause further vasoconstriction to the area,
and providing broad spectrum antibiotics.
You may also then do an embolectomy
or surgery if necrotic bowel has formed.
So as we mentioned, there are several
types of acute mesenteric ischemia.
The first is an arterial embolus,
most commonly it's from cardiac origin
due to any of these
cardiac condition listed here.
You may also get an acute thrombosis
on top of overlying atherosclerotic disease.
A third mechanism is
non-occlusive mesenteric ischemia.
This is when in general, you just have
vasoconstriction of your splanchnic vessels,
due to low cardiac output or medications
that are causing vasoconstriction.
And lastly, you may also
have a venous thrombosis.
Most commonly this occurs
in hypercoagulable states,
so in settings like infection, severe
inflammation as with pancreatitis,
medications that cause this, or cancer.
So now that we've gone through
that, let's return to our case.
We have our 78-year-old man
with known atherosclerotic disease
who now has sudden
onset severe abdominal pain.
He has a known history
of atrial fibrillation.
And on exam, he has abdominal
pain out of proportion to the findings.
Importantly, we have already ruled out C. difficile
infections since that is a thing on your differential.
So, you should now recognize
this clinical constellation of symptoms
in the setting of his known
atherosclerosis and A.fib
which would prompt you to a diagnosis of an acute
mesenteric ischemia likely from a cardiac embolus.