Welcome, today we'll be discussing
disorders of the large intestine.
So we'll begin with a case.
We have a 68-year-old woman who presents to the ED with
3 days of abdominal pain in the left lower quadrant.
She has had subjective fevers and
chills but no changes in her urination,
bowel habits, nausea, vomiting
or blood in her stool.
Her past medical history includes hyperlipidemia, and
irritable bowel syndrome with chronic constipation.
Her vitals show a temperature of 38, heart rate
of 100 and she appears to be in mild discomfort.
She has mild tenderness to palpation in the left
lower quadrant without rebound or guarding.
Her labs are notable for a
leukocyte count of 13,500.
And her complete metabolic panel
and urinalysis is unremarkable.
What would be an appropriate
next diagnostic step?
So before we answer that, let's go
through some key features of this case.
She has acute left lower quadrant
abdominal pain with fevers and chills
which would prompt you to
consider an infectious cause.
She does have a history of chronic
constipation and on exam,
she's febrile, tachycardic, has leukocytosis with a
potentially localizing sign of abdominal tenderness.
So we'll go through a very broad
differential diagnosis for this patient.
If you were to see this patient presenting to you in the
ED, you would first think about gastrointestinal causes.
Those may include diverticulitis, ischemic bowel,
infectious colitis and other things listed here.
If we think anatomically now,
moving on from the GI system,
you also have to worry
about the genitourinary system.
So things like cystitis and
pyelonephritis can also present this way.
Because she's a woman, you should always have
gynecological causes on your differential.
So a ruptured ovarian cyst or ovarian
torsion could lead to her presentation.
You also must remember that there are
large vascular structures in this area,
so inflammation of the aorta or various
blood vessels may lead to vasculitis.
She may also have
and then, kind of the miscellaneous areas,
she may have abscess in her abdominal wall,
a hematoma, an abscess in her psoas muscle or
hemorrhage into her retroperitoneal space.
So this is a very broad differential, so let's think
critically through it and kind of narrow it a bit.
So, because she's coming in with left lower quadrant pain, you
should always have diverticulitis at the top of your differential.
Moving on to the GU system, she doesn't have any
particular symptoms of the genitourinary tract
and her urinalysis is negative, so you can kind
of cross these things off your differential.
Because she's a woman, you should
always keep a ruptured ovarian cyst
and ovarian torsion on your
differential and rule them out.
And then consider that she may
also have a psoas abscess
since this may correspond with
her anatomic location of pain.
All of the other causes
listed here are possible
but less likely based on the acute(ness) of her
presentation and the location of her pain.
So now let's review
some important definitions.
We mentioned diverticulitis earlier.
There are several different terms
that we should go through first.
The first is "diverticulum".
So this is when you have just an
asymptomatic outpouching in the colonic mucosa
just due to weakness
in the muscle wall.
"Diverticulosis" just refers
to the presence of diverticula.
When we talk about "diverticulitis", that's
when you have inflammation of a diverticulum.
So here you can see
different types of diverticulum.
On the bottom right, this is an
example of a regular diverticulum.
Above that, you see a ruptured diverticulum
and to the left, you see an example
of diverticulitis where the outpouching
then gets obstructed
and leads to inflammation.
So now let's go to some risk
factors of diverticulitis.
Advanced age is the first risk factor
as most cases occur after age 85.
This is because as we age, the muscle
wall in our colon becomes weaker.
Patients who have a history of chronic constipation
are also at risk for developing diverticulitis.
This is because with frequent straining
for the passage of bowel movements,
this can lead to weakness
in the colonic wall.
People who have low dietary fiber or
do not exercise much are also at risk.
Obesity is another risk factor.
And prior episode of diverticulitis puts
you at risk for having more in your lifetime.
So acute diverticulitis is caused by a blocked
diverticulum which then leads to a nice space
where bacteria are able to
proliferate and cause inflammation.
Patients will come in with abdominal pain, typically
they'll note always in the left lower quadrant.
They may have fever and they may
have a change in their bowel habits.
The diagnosis is mostly made based on clinical
symptoms but if they have severe presentation,
you should consider doing a CT imaging
to look for any complications.
So here on the right, you
see an example of a CT scan.
The horizontal areas are showing
areas of perforated diverticulitis
and the downward arrows at the top of the image show
you several pockets of free air in the abdomen.
This is always a very concerning sign as this tells
you that you have a perforated viscus or organ
and in this case has resulted
from a perforated diverticulum.
So treatment is by allowing bowel rest,
you may put patients on a liquid diet.
You should cover for a
colonic flora with antibiotics,
so targeting gram negative
and anaerobic bacteria.
And if you see any complications,
you should consult surgery.
The mainstay of treatment
however, is just prevention.
So counseling patients on a high fiber diet to
make sure that they don't develop future episodes.
We spoke a bit about
complications of diverticulitis.
There are several complications
of which you should be concerned.
The first is an abscess.
This is when an area of infection perforates outside
of the diverticulum and then becomes walled off.
You can see here several air-fluid levels that
are indicative of an abscess on the CT scan.
The next common complication is a fistula.
So anytime you have
inflammation of the colon,
it can cause an abnormal connection
or tracks to form between two structures.
Here in the CT scan, you see an
example of a sigmoid diverticulitis
and the area points to a fistulous
tract leading to an abscess.
The last complication is the most
dreaded of all, which is peritonitis.
This is when you just have perforation of
the diverticulum into the free abdomen
which leads to the development of free air and
then inflammation of the peritoneal space.
Here on this CT scan, this is
a very concerning finding.
You see a large amount of
free air at the top of the abdomen
which indicates that
something has perforated.
So now we return to our case.
We have a 68-year-old woman who is
having acute left lower quadrant abdominal pain
with fevers and chills.
She does have a history of chronic constipation
which puts her at risk for diverticulitis
and her exam and vital signs are all
consistent with this presentation.
So, the next appropriate step in diagnosis
would be to perform a CT image of the abdomen
to look for diverticulitis
and its any complications.