1/ #MedTwitter, it’s time for #ClinicalReasoning practice with Bayes’ Theorem!
Follow along and let us know what you’re thinking!
72-yo-woman with HTN, DM, & knee replacement (10 days ago) p/w pleuritic chest pain, dyspnea and cough.
Follow along and let us know what you’re thinking!
72-yo-woman with HTN, DM, & knee replacement (10 days ago) p/w pleuritic chest pain, dyspnea and cough.
2/ As you walk down to the ER, you have diagnoses in your mind that are somewhere between unlikely and very likely.
This likelihood is known as:
This likelihood is known as:
3/ ANS: Pretest probability
On exam, her temperature is 100.1F, HR 108 and SaO2 88% RA. Her lower extremities are without swelling, tenderness, or erythema.
Basic labs are in process. What else would you order?
We’d love to see your reasoning in the replies!
On exam, her temperature is 100.1F, HR 108 and SaO2 88% RA. Her lower extremities are without swelling, tenderness, or erythema.
Basic labs are in process. What else would you order?
We’d love to see your reasoning in the replies!
4/ ANS: 1, 2, 4 are all reasonable, depending on your pretest probability for each disease on your differential. It’s worth noting that we’re all going to have varying pretest probabilities as they are largely a product of experience. These probabilities guide further testing.
5/ Labs and imaging come back.
WBC 10.2 w/ neutrophil predominance, D-dimer elevated to 1200ng/ml, and CXR is shown w/ right lower lobe opacity. (Image courtesy of Dr David Pryde, Radiopaedia.org, rID: 39000)
WBC 10.2 w/ neutrophil predominance, D-dimer elevated to 1200ng/ml, and CXR is shown w/ right lower lobe opacity. (Image courtesy of Dr David Pryde, Radiopaedia.org, rID: 39000)
6/ What’s most likely based on your new posttest probability?
7/ She’s diagnosed with PNA & started on abx (ceftriaxone/azithromycin).
On day 4 of abx, vitals are T 99.4, HR 110. She requires 3L supplemental O2. WBC 9.6 w/ neutrophil predominance.
How does the lack of response to abx change the probabilities of diseases on your DDx?
On day 4 of abx, vitals are T 99.4, HR 110. She requires 3L supplemental O2. WBC 9.6 w/ neutrophil predominance.
How does the lack of response to abx change the probabilities of diseases on your DDx?
8/ What would you do next?
9/ The lack of response to abx, increases the pretest probability of a PE, prompting the need for a CTPA.
CTPA shows a segmental PE c/b wedge-shaped pulmonary infarct. The opacity on her CXR is known as Hampton’s Hump! (Learn more from @Radiopaedia here: bit.ly/2q2t80q)
CTPA shows a segmental PE c/b wedge-shaped pulmonary infarct. The opacity on her CXR is known as Hampton’s Hump! (Learn more from @Radiopaedia here: bit.ly/2q2t80q)
10/ Thanks for joining us! We hope this case reinforces concepts from @jackpenner’s blog post “Pre & Posttest Probability” bit.ly/36hudC4
We’d love to hear your reflections/feedback!
And check out this amazing case by @DxRxEdu for more practice bit.ly/36nUG0R
We’d love to hear your reflections/feedback!
And check out this amazing case by @DxRxEdu for more practice bit.ly/36nUG0R
