USMLE® Step 1 style questions USMLE
A 42-year-old woman, gravida 3 para 3, is brought to the emergency department due to severe abdominal pain that started 3 hours ago. She describes the pain as sharp, constant, and rates it as 7/10 in intensity. Since the pain started, she has been feeling nauseous and has vomited twice. She reports a few episodes of similar abdominal discomfort in the past but says that this time it “feels different.” Temperature is 38.0°C (100.4°F), pulse is 80/min, and blood pressure is 135/85 mmHg. BMI is 32 kg/m2. The patient is in acute distress due to pain and points to the upper abdomen. The abdomen is tender to touch. No rebound tenderness or hepatomegaly is present. An abdominal ultrasound is performed and reveals a normal common bile duct with concomitant gallbladder wall thickening and free fluid around the gallbladder. Laboratory results are obtained and shown below:
|Leukocyte count||15,000 mm3|
|Platelet count||250,000 mm3|
|Mean corpuscular volume||90 μm3|
|Alanine aminotransferase||18 U/L|
|Aspartate aminotransferase||20 U/L|
|Alkaline phosphatase||65 U/L|
Acute cholecystitis exam links
Content Reviewers:Rishi Desai, MD, MPH
Contributors:Tanner Marshall, MS, Vincent Waldman, PhD
Acute cholecystitis, or inflammation of the gallbladder, usually comes about because of a gallstone being lodged in the cystic duct. The cystic duct is the one that leaves the gallbladder and connects to the common bile duct.
So let’s say this person’s gallbladder’s got a few gallstones in it, and they go to eat a hamburger, the small intestine secretes cholecystokinin, sometimes shortened to CCK, into the blood where it makes it’s way to the gallbladder, and signals it to squeeze out some bile to give it a hand with digestion of that hamburger. The gallbladder contracts and one of these stones gets lodged right in the cystic duct, which blocks bile flow...now what? Well this person probably start experiencing some pain, specifically midepigastric pain, which happens because the gallbladder’s trying to squeeze on a blocked duct...and just like if you squeezed a partly filled balloon with the end blocked off, it physically stretches out and irritates the nerves in the gallbladder and duct. This can also lead to nausea and vomiting, which can last for long periods of time. And as the gallbladder squeezes more and more, the stone might get even more stuck, and at this point the bile, being stuck in the same place, or in a state of stasis, becomes a kind of chemical irritant, and causes the mucosa in the walls to start secreting mucus and inflammatory enzymes, which results in some inflammation, distention and pressure buildup.
At this point, there might also start to be some bacterial growth, most commonly E coli which is all over the gut, but also Enterococci, Bacterioides fragilis, and Clostridium, which can also be found there. As it sort of balloons up, the pain might start to shift to the right upper quadrant, and it’ll be this kind of dull, achy pain that can even radiate up to the right scapula and shoulders. After a while, bacteria starts invading into the gallbladder wall and eventually through the wall, causing peritonitis, inflammation of the peritoneum, which can cause what’s called rebound tenderness, where pain is brought on when pressure is actually taken off the belly rather than when it’s applied.
Here’s another physical exam trick, though. We know that while a patient takes in a deep breath, the diaphragm pushes down on the gallbladder. You can apply pressure onto the abdomen to keep the abdominal contents from sliding downward . With the abdominal contents roughly pinned in place, you can ask a patient to take a deep breath and if the diaphragm pushes down on their gallbladder (which remember s pinned in place), that will cause pain, forcing the patient to stop breathing in further and that’d be a positive murphy’s sign which can help with diagnosis. Finally, since the bacteria has started invading the mucosa and the tissue, the patient’s immune system kicks in, ramping up the neutrophils in the blood and leading to neutrophilic leukocytosis and likely also causing a fever.
At this point, one of two things can happen, first, the stone could fall out of the cystic duct, which is great, and then the symptoms and cholecystitis eventually subside, this actually happens in the majority of cases. The other thing that could happen though is that the stone doesn’t fall out...And if that’s the case, pressure can keep building up, eventually so much so that it starts pushing down on the blood vessels supplying the gallbladder with blood, which means blood can’t get to the gallbladder and the tissue starts to get ischemic, leading to gangrenous cell death, which is cell death due to not having enough of a blood supply. As the gallbladder walls weaken, it might eventually perforate or rupture. This causes sharp pain and if left untreated, could allow bacteria to get into the blood supply and cause sepsis. If it’s allowed to get this far, it’s possible the patient needs a cholecystectomy, or a removal of the gallbladder.
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