Hey folks, welcome back to another question walkthrough! I’m Dr. Zeb,
and today we’re going to review a question that requires us to differentiate causes of
abdominal pain and vomiting. You can click on the question link to first try to answer it.
After that, let’s start by reading the lead-in so we know what’s expected of us.
“Further evaluation of the patient is most likely to show which of the following?”
Alright, we need to come up with a working hypothesis of the most likely diagnosis.
Although I often skim through diagnostics for confirmatory findings first, this question
doesn’t give us much, so let’s read from the top now to start forming differentials.
“A 48-year-old woman comes to the emergency department because of
increasingly severe right upper abdominal pain, fever, and nonbloody vomiting for 5
hours. The pain is dull and intermittent and radiates to her right shoulder. During the
past 3 months, she has had recurring abdominal discomfort after meals.“
It’s time to break out those illness scripts: what top differentials
should I have on my radar for right upper abdominal pain that radiates to the shoulder,
as well as vomiting and a 3-month history of postprandial abdominal discomfort?
Right, biliary conditions like cholelithiasis (so symptomatic gallstones), cholecystitis
(so inflammation of the gallbladder), cholangitis (inflammation of the bile duct),
and choledocholithiasis (gallstones in the bile duct). The 3-month history of
postprandial abdominal discomfort is consistent with biliary colic,
caused by impaction of a gallstone in the neck of the active gallbladder during digestion.
Peptic ulcer disease is also a possible explanation as gastric acid agitates the
damaged mucosa, although the pain typically radiates from the center upper or mid-abdomen
and is classically described as “gnawing” or “burning.”
So continuing on, the fever and acute worsening should especially make us think of?
Right, an infectious condition such as acute cholecystitis or cholangitis.
At this point, instead of reading through all of the vignette,
we’re going to look for a couple key findings that will help us narrow down the diagnosis.
What is a classic exam finding in patients with acute cholecystitis?
Absolutely! A positive Murphy sign - so if a patient stops inspiration to avoid pain
caused by the examiner’s hand pushing against the inflamed
gallbladder while palpating the right upper quadrant.
And sure enough, there it is: “Abdominal examination shows right upper quadrant
abdominal tenderness and guarding. Upon deep palpation of the right upper quadrant,
the patient pauses during inspiration.”
What other differentiator between cholecystitis and cholangitis should I look for?
Yes, biliary obstruction, which can lead to symptoms of?
Elevated bilirubin such as icterus or even jaundice.
And there is no mention of these clinical features.
What else are we interested in?
Lab values and any imaging. We don’t have imaging, but more on that later.
Regarding labs, which findings, in particular, would we like to see?
Right, if leukocytosis or other signs of inflammation, such as elevated CRP, are present.
If bilirubin, ALP, and GGT are elevated,
indicating cholestasis - which is rather aligned with cholangitis.
We would be interested in AST and ALT, which should be normal
or possibly slightly elevated due to inflammation of the surrounding liver.
Lastly, if lipase and amylase are elevated, we should also consider acute biliary pancreatitis.
Other than slightly increased ALT and AST, all the other tests are normal. Despite
the inflammation of cholecystitis, it’s not uncommon for leukocytes to still be within
normal limits at the time of presentation, so this shouldn’t dissuade us from our hypothesis.
Based on our clinical reasoning, acute cholecystitis is the most likely diagnosis.
But before we try to answer the question, let’s consider briefly the pathophysiology
of acute cholecystitis. This condition is usually caused by?
Yes, obstructing cholelithiasis, as the cystic duct becomes blocked from gallstones,
leading to distention and then inflammation of the gallbladder.
It makes sense, don’t you think? I mean, after all,
the gallbladder’s favorite band is the rolling stones, right?
This is known as acute calculous cholecystitis. Secondary bacterial infection may also be present,
with E. coli, Klebsiella, Enterobacter, and Enterococcus as the most common culprits.
Think of them “Entering” a gallbladder’s “CHEEEK” to help you remember this.
Now, is this the only form of cholecystitis? About 5-10% of cases are acalculous cholecystitis,
which often occurs in critically ill patients due to bile stasis and
reduced perfusion of the gallbladder. It’s high yield to also know about this type,
which you can further test yourself on with this question.
Given the 3-month history of postprandial discomfort,
this patient likely has a history of gallstones. Are all gallstones the same?
About 80% are cholesterol stones,
while the rest are so-called pigment stones. 10% are black pigment stones resulting from
excess unconjugated bilirubin usually due to hemolysis and the last 10% are mixed,
brown stones of excess bilirubin and cholesterol resulting from biliary tract infection.
Knowing that cholesterol gallstones are the most common cause of cholecystitis,
what risk factors should we be considering?
There’s a well-known mnemonic that covers this, known as the 5, or more sometimes, 6 F’s,
which include Female, Fat, Fertile, Fair-skinned, Forty, and sometimes Family history. These
clinical features are statistically more common in individuals with symptomatic cholelithiasis.
Now, I know what some of you may be thinking: How does he have the gall… to use that mnemonic?
Pfff...
But in all seriousness, although based on statistics, this mnemonic has received some
controversy, and rightfully so, because it may form a stereotype that can ultimately lead to
misdiagnosing patients who fit the profile and overlooking those who don’t. With that said,
it’s still a useful mnemonic device to recall common risk factors and subjectively determine the
probability of cholelithiasis. Just remember that it should be taken with a grain of… bile… salt.
With that in mind, let’s answer the question. Looking through the options, sure enough,
a history of multiple past pregnancies would match the “fertile” risk factor we mentioned. The risk
of gallstone disease is about 10 times greater among multiparous women than nulliparous. This is
due to high estrogen levels during pregnancy that increase the secretion of cholesterol into bile,
while high progesterone levels decrease the production of hydrophilic bile acids,
resulting in a decreased ability of bile to separate from cholesterol.
The combination of these effects leads to the supersaturation of bile with cholesterol,
which predisposes the patient to gallstone disease.
This same mechanic... ah... mechanic?
Beep. This same mechanism also explains why women, who have more estrogen and progesterone,
are more likely than men to have gallstones in general. Being overweight is associated with
hypercholesterolemia and potentially higher estrogen levels in some cases. Regarding
family and even fair-skinned, these associations likely involve genetics and possibly diet.
As for the age of 40 or higher, this is basically referencing an increased
likelihood with older age, probably because of more time for extra bile products to accumulate.
With the correct option behind us, let’s examine some of the key learning
points from the other options, which are all associated with some important differentials.
Elevated carbohydrate deficient transferrin is typically seen with heavy alcohol use,
which is not a risk factor for gallstones. In fact,
mild alcohol consumption even decreases the risk of gallstone disease. This answer
might have been tempting, though, had you been thinking the patient has acute pancreatitis,
which is often caused by alcohol consumption and also manifests with abdominal pain,
vomiting, and low-grade fever. But this condition wouldn’t explain the other findings we discussed.
A history of recent travel to Indonesia, or any area with insufficient sanitation or limited
access to clean water - particularly in parts of Africa, Asia, Mexico, Central and South America,
and the Caribbean islands - should raise suspicion of hepatitis A as a potential cause of vomiting,
fever, and right upper quadrant pain due to swelling of the liver and stretching of the
Glisson capsule. But hepatitis A would not explain this patient’s referred pain in the
right shoulder or positive Murphy sign. It also typically would cause severe jaundice
and high serum transaminase levels - AST levels are usually over 20 times the normal upper limit.
A history of recurrent sexually transmitted infections might be tempting to choose had
you suspected Fitz-Hugh-Curtis syndrome, a form of perihepatitis that can occur as
a complication of pelvic inflammatory disease due to chronic bacterial infections such as Chlamydia
trachomatis or Neisseria gonorrhoeae. Because of inflammation of the liver capsule with adhesions,
Fitz-Hugh-Curtis syndrome can closely resemble acute cholecystitis with right
upper quadrant pain, fever, vomiting, and even referred pain in the right shoulder.
But it’s unlikely here given the lack of PID symptoms like pelvic pain, dysuria,
or vaginal discharge, and wouldn’t explain a positive Murphy sign or biliary colic.
Frequent, high-pitched bowel sounds indicate increased intestinal activity,
which can occur after eating, with diarrhea, or when working against mechanical obstruction. Acute
cholecystitis, which can lead to peritonitis, is more likely to be associated with absent bowel
sounds resulting from paralytic ileus rather than mechanical. Granted, mechanical bowel
obstruction can be caused by a large gallstone within the small intestine, which is known as
gallstone ileus and is even high-yield. However, gallstone ileus is quite rare, and abdominal x-ray
would typically show air within the biliary tree, unlike this patient’s normal findings.
The growth of gram-negative organisms from a urine culture would indicate a urinary tract
infection such as pyelonephritis, which can present with fever, vomiting,
and abdominal pain. However, pyelonephritis typically presents with flank pain and not
the right upper quadrant nor referred shoulder pain seen in this patient.
You can read up on all of these important conditions and test yourself further
with associated questions by clicking on this link.
Let’s consider briefly what other questions might we get for this topic:
As “bile” as it may be, the NBME loves to test your knowledge of risk factors on all of their
exams - both directly, as with this question, or as a supporting feature for diagnosis.
So you should know them very well!
We already discussed the most common risk factors covered by the 6 F's.
What are some other high-yield risk factors for cholesterol stones?
Right, medications such as estrogen therapy and oral contraceptive, or fibrates,
which decrease the synthesis of bile acid via inhibition of cholesterol 7-α hydroxylase.
Malabsorption, which reduces bile salt absorption,
for example, due to Crohn disease, ileal resection, or cystic fibrosis.
And rapid weight loss, like after bariatric surgery, which causes
the liver to secrete extra cholesterol into bile as the body metabolizes fat.
Regarding diagnostics, in addition to the labs we discussed here,
being asked about the next best steps or expected findings is definitely fair game and would be?
Absolutely, transabdominal ultrasound, which commonly shows?
Extension of the gallbladder with a thickened wall that has edema, likely with a so-called
double-wall sign. Gallstone shadowing and biliary sludge are also likely findings.
And if ultrasound is inconclusive? Then a HIDA scan would be indicated. The lack of visualizing
the radioactive tracer in the gallbladder within 4 hours supports a cystic duct obstruction.
And what about management? Well, this could also be its own video, but to summarize:
empiric antibiotic therapy and cholecystectomy, usually laparoscopic,
are the mainstays of treatment. In more severe cases especially when surgery is not yet possible,
percutaneous drainage - so cholecystostomy, may be considered.
The key takeaways of this question are:
Identify acute cholecystitis based on common findings such
as right upper quadrant colicky pain that radiates to the right shoulder,
fever, vomiting, and a history consistent with gallstone disease, the most common cause.
Recall the risk factors of symptomatic cholelithiasis, including the 6 F’s of Female,
Fat, Fertile, Fair-skinned, Forty, and Family history for cholesterol stones.
And that’s it for this question! I’d appreciate a thumbs up, comment,
or subscribe if you found the video helpful, and check out any of the links
to the question and social media channels in the description for even more content.
As always, remember that hard work pays off, so keep up the studying. You’ve got this.