Explanations for the 2017-2018 Official Step 2 CK Practice Questions

The updated 2017-18 official “USMLE Step 2 CK Sample Test Questions” PDF, released in May and available here.

The PDF set is completely unchanged from last year. You can read the complete explanations for last year’s set here.


As for the updated multimedia questions found only in the online version:

Block 1

7. A – Classic Moro reflex, entirely expected and normal until it disappears around age 4 months. If you have never seen a newborn before, also note that the mom is concerned about delayed milestones at two weeks of age, which is a red flag for BS: babies aren’t even smiling socially yet by two weeks.

Block 2

3. D – Pill-rolling resting tremor of Parkinson’s disease secondary to loss of dopamine neurons in the substantia nigra.

18. A – I’m going to point out that a normal healthy kid with no cardiac history or symptoms and no family history of sudden cardiac death for a pre-sports physical is probably going to have a benign exam no matter what you think you hear. HOCM is what you want to exclude theoretically, but here we don’t have a real systolic murmur, just a little vibratory flow murmur at LLSB.

33. E – This one is a bit silly. The lung exam is normal outside of the super common basilar crackles. Everything except for PE you would expect to hear a more impressive auscultation abnormality. But for this question: B and C take longer than 3 days. D we would expect fever, productive cough etc. Bronchitis would be possible, but still more often to have at least productive cough if not fever. PE, on the other hand, classically has a nonproductive cough, hypoxemia, and tachycardia. All three are present. And then they mention her med: OCPs, which are an important predisposing factor for PE in young women for whom it is otherwise a rare entity. Young lady on OCPs is a classic set-up for an STD question (who needs condoms?) or a PE question, one of the two.

Block 3

12.1 D – Statistical significance (a low p-value) does not equal clinical significance. A favorite teaching point when it comes to interpreting literature.

12.2 C –A & D are conjectures: the kind of statements people drop inappropriately in the conclusion of a weak paper to make it sound important. E is an exclusion criterion. B is the opposite: including 0 is equivalent to something not being significantly different.


  1. Thank you, but regarding the statistics question, females were only 16% of the study, isn’t this an enough limitation for the generalization of the study result, I know that the study measurements were purely numerical and unimportant when taking about improved mortality or quality of life, but still there is a few number of females in this study ??

    • Single best answer: if the results are clinically meaningless, then that is more important than the fact that the result may also not be generalizable.

      Would the current results matter if the study was 50% men and 50% women? No, it would still be useless.

      Whereas would the study be potentially useful if EF had actually changed a lot (even if it was mostly men)? Quite possibly.


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