Getting into NBME question writer's mindset (example)

[Pinkleton]

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So I have a strange problem where I get a lot of NBME questions wrong (even for step 1) and I'm trying to devise a system to fix this. The weird thing is I destroy UWorld questions on a consistent basis (I'm getting mid to high 80's now on timed, random blocks). I know the level of thinking that UW expects, and I feel like I can't figure that out with NBME questions. Here is a summary of an old NBME question from Form 1.

70 y.o. with increasing abdominal pain for 2 days. On peritoneal dialysis for 18 months and got last treatment 2 hours ago. She appears toxic, 102.2 F, BP 140/90 mm Hg. Abdomen is distended and diffusely tender to deep palpation with rebound tenderness. WBCs 18,000. Which of the following is the most appropriate next step?

A ) X-ray films of the abdomen
B ) Comparison of abdominal fluid amylase with serum amylase activity
C ) Gram's stain of abdominal fluid
D ) Ultrasonography of the abdomen
E ) CT scan of the abdomen and pelvis

There is no official answer, but most people online seem to have agreed on C. I absolutely hated this question. My immediate thought was that we need a paracentesis to check for neutrophils >250 to confirm SBP and maybe send off for CULTURE. But the choice says GRAM STAIN. But a gram stain tells you nothing! (confirmed on emedicine) So I'm thinking...hmm is the purpose of this question to know that I would tap the ascites in this situation? Seems like an NBME thing to do. In UW I would confidently pick A and expect the explanation to talk about how crappy a gram stain is.

The reason I'm thinking A is that maybe the patient has a perforated bowel. Not the most likely scenario in my mind but more likely to tell you how to proceed than a inconclusive gram stain of her ascites.

Any advice on my thinking process? Also, what do you guys think the correct answer is? I have my doubts about C

 

[UMN]

I learnt this recently. Apparently pxs who get SBP secondary to cirrhosis (ascites) only have a fever and appear toxic. They do not have REBOUND tenderness or Involuntary guarding. And yea gram stain is not very helpful in SBP coz the thrs a high chance that u wont find anything on gram stain. If a px seems toxic and has REBOUND tenderness or Involuntary guarding its most likely a secondary POLYMICROBIAL (not jus ecoli like SBP) infection causing PERITONITIS and gram stain could be very helpful in such cases. This usually happens in pxs who undergo regular peritoneal dialysis. But even in such a case if they give an option for paracentesis, that would be the first step. This explanation was is UWSA question 6907. Hope this explanation made sense 🙂

 

[DermViser]

So I have a strange problem where I get a lot of NBME questions wrong (even for step 1) and I'm trying to devise a system to fix this. The weird thing is I destroy UWorld questions on a consistent basis (I'm getting mid to high 80's now on timed, random blocks). I know the level of thinking that UW expects, and I feel like I can't figure that out with NBME questions. Here is a summary of an old NBME question from Form 1.

70 y.o. with increasing abdominal pain for 2 days. On peritoneal dialysis for 18 months and got last treatment 2 hours ago. She appears toxic, 102.2 F, BP 140/90 mm Hg. Abdomen is distended and diffusely tender to deep palpation with rebound tenderness. WBCs 18,000. Which of the following is the most appropriate next step?

A ) X-ray films of the abdomen
B ) Comparison of abdominal fluid amylase with serum amylase activity
C ) Gram's stain of abdominal fluid
D ) Ultrasonography of the abdomen
E ) CT scan of the abdomen and pelvis

There is no official answer, but most people online seem to have agreed on C. I absolutely hated this question. My immediate thought was that we need a paracentesis to check for neutrophils >250 to confirm SBP and maybe send off for CULTURE. But the choice says GRAM STAIN. But a gram stain tells you nothing! (confirmed on emedicine) So I'm thinking...hmm is the purpose of this question to know that I would tap the ascites in this situation? Seems like an NBME thing to do. In UW I would confidently pick A and expect the explanation to talk about how crappy a gram stain is.

The reason I'm thinking A is that maybe the patient has a perforated bowel. Not the most likely scenario in my mind but more likely to tell you how to proceed than a inconclusive gram stain of her ascites.

Any advice on my thinking process? Also, what do you guys think the correct answer is? I have my doubts about C

Go here and you can see how they exactly they write NBME style questions: http://www.nbme.org/publications/item-writing-manual.html

But to your question, I think it's more to see which one is most important to do first to guide your management of the patient.

 

[Pinkleton]

I learnt this recently. Apparently pxs who get SBP secondary to cirrhosis (ascites) only have a fever and appear toxic. They do not have REBOUND tenderness or Involuntary guarding. And yea gram stain is not very helpful in SBP coz the thrs a high chance that u wont find anything on gram stain. If a px seems toxic and has REBOUND tenderness or Involuntary guarding its most likely a secondary POLYMICROBIAL (not jus ecoli like SBP) infection causing PERITONITIS and gram stain could be very helpful in such cases. This usually happens in pxs who undergo regular peritoneal dialysis. But even in such a case if they give an option for paracentesis, that would be the first step. This explanation was is UWSA question 6907. Hope this explanation made sense 🙂

Thanks for the great explanation, I see where my thinking was wrong. I guess technically you didn't even need to know the difference between SBP and peritoneal peritonitis to get this question right. Taking out the fluid and doing something with it is what they were going for. I'm stopping UW and doing more of these type questions haha

 

[res1cue]

Uworld definitely writes "better" questions. You can follow their logic better and definitively back it up with resources.

NBME-style questions are much more vague and often times the correct answer I am still thinking "I am not sure about that..."

I am struggling with this too, wish they would contract Uworld to write board questions