Ranking and Ruling Out a Differential in a Composite Adult With Pleuritic Chest Pain After a Long Flight
Student Name
Department of Nursing, Herzing University
NU 611: Clinical Decision-Making
Unit 4 Assignment
Instructor Name
Month Day, Year
Presentation and the Question the Visit Has to Answer
Every detail in this paper is a composite. The patient, the clinic, and the visit are assembled from ordinary primary care presentations, so no individual, employer, or record is described here, and nothing has been de-identified because nothing real was used. The composite is a 46 year old woman, called Ms. R below, who comes to a family practice clinic with four days of right-sided chest pain that sharpens on deep breathing and with breathlessness after one flight of stairs. She returned nine days ago from a nine hour flight, takes a combined oral contraceptive, and reports no prior clot, no active cancer, no surgery in the past year, no fever, no hemoptysis, and no calf pain.
Intake vital signs are temperature 37.4 C, heart rate 104, respiratory rate 22, blood pressure 128/78, and oxygen saturation 94 percent on room air. On examination her chest wall is not tender to palpation, breath sounds are symmetric without crackles or a rub, heart sounds are regular without a murmur, and both calves are soft with equal circumference measured 10 cm below the tibial tuberosity. She speaks in full sentences and is not in distress at rest. The question this visit has to answer is not what could cause pleuritic chest pain, since a long list will always exist, but which causes can be excluded safely today and which cannot be excluded without imaging.
The reasoning below is a record of how a decision was reached, written for teaching, and it is not clinical advice and not a protocol for any person or setting. It follows the order an experienced clinician uses under time pressure. A list is generated wide enough to hold the dangerous as well as the common. That list is then ranked by two quantities at once, the prior probability of each candidate in a patient like this one and the cost of missing it. Each candidate is finally tested against findings that discriminate between diagnoses rather than findings that merely fit the diagnosis already in mind, which is where anchoring does its damage (Croskerry, 2009).
Ranking the Differential and Arguing Each Candidate Down
Ranked by likelihood and by the cost of a miss together, the working list is pulmonary embolism first, community acquired pneumonia second, musculoskeletal chest wall pain third, pericarditis fourth, acute coronary syndrome fifth, and spontaneous pneumothorax sixth. The order is not a guess about what is most common in a clinic waiting room. Chest wall pain is by far the most frequent cause of pleuritic pain in ambulatory practice, and it still sits third here, because a common diagnosis that costs nothing to miss for an hour ranks below an uncommon one that can kill within a day. Ranking is a statement about what has to be resolved first, not a prediction of the final answer.
Pulmonary embolism is tested first with the Wells criteria. She scores 1.5 for a heart rate above 100 and 3.0 for pulmonary embolism being at least as likely as any alternative diagnosis, and she scores zero on the remaining five items: no clinical signs of deep vein thrombosis, no immobilization of three days or more and no surgery in the previous month, no previously confirmed venous thromboembolism, no hemoptysis, and no malignancy treated within six months. Her total is 4.5. A total above 4.0 places her in the pulmonary embolism likely group of the two tier rule, and that single number changes which tests are permitted to end the workup (Wells et al., 2000; Raja et al., 2015).
Each remaining candidate is then argued down with a finding that discriminates. Pneumonia is demoted rather than excluded: the absence of fever, productive cough, and focal crackles lowers it, but a chest radiograph is the step that would settle it. Musculoskeletal pain is argued against on one point, that her pain is not reproducible with palpation or with movement of the shoulder girdle, which is the finding that ordinarily carries it. Pericarditis is lowered because the pain does not change with posture and no friction rub is audible on repeated listening. Acute coronary syndrome is lowered because the pain is pleuritic rather than exertional and comes without diaphoresis or radiation, although an electrocardiogram is still obtained because the cost of a miss is high. Pneumothorax is lowered by symmetric breath sounds and by an onset over days rather than seconds.
Ruling out means three different things in this paper, and keeping them apart is what makes the ranking defensible. A diagnosis can be excluded by a finding sensitive enough that its absence is decisive. A diagnosis can be made improbable enough that no further testing is warranted, which is a judgment about thresholds rather than about certainty. A diagnosis can also be demoted but retained, waiting on a result that has not returned. Only pneumonia sits in the third category at the end of this visit, while musculoskeletal pain, pericarditis, and pneumothorax sit in the second. Nothing here is excluded in the first sense, and saying so plainly is more honest than a note reading negative for all of the above.
The Decision Point and What Would Have Changed It
The decision point in this case is a single fork: whether the pretest probability is low enough that the pulmonary embolism rule out criteria may close the workup, or high enough that a negative D dimer would not be sufficient and imaging becomes the next step. Naming the fork matters because the two branches are not two versions of one plan. One branch ends the visit with reassurance and return precautions. The other commits the patient to contrast, to radiation, and to a result that will be acted on the same day. A note recording only the order that was placed hides which branch was taken and hides the reason for it.
Two findings settle the fork here. The rule out criteria are built for patients whose pretest probability is already low, so a Wells total of 4.5 puts this composite outside the population the rule was validated in, before any of its eight items are checked (Kline et al., 2008). Even if the rule were in scope, three items fail: a heart rate of 104 is not below 100, a saturation of 94 percent is not at or above 95 percent, and she uses exogenous estrogen. In the likely group a D dimer also stops being the discriminating test, because a negative result applied to a prior probability this high leaves a posterior probability above the threshold most clinicians accept for sending a patient home (Raja et al., 2015). Imaging is the next step, and it is the next step for a stated reason rather than out of caution.
Three changes would have moved the decision to the other branch, and stating them belongs inside the reasoning rather than after it. A composite aged 34, off hormonal contraception, with a heart rate of 88 and a saturation of 98 percent would have scored 0 on Wells, would have been in scope for the rule out criteria, and could have satisfied all eight items, which ends the workup without a blood draw. A composite with unilateral calf swelling would have gained 3.0 more points and passed the fork entirely, going to imaging without a stop at probability. A composite in shock with a saturation of 86 percent does not belong at this fork at all, because instability changes the setting rather than the test. Recording which of these was true is how a decision stays auditable months later, when the chart is all that remains of the thinking (Agency for Healthcare Research and Quality, 2019).
References
Agency for Healthcare Research and Quality. (2019). Diagnostic errors. PSNet. https://psnet.ahrq.gov/primer/diagnostic-errors
Croskerry, P. (2009). A universal model of diagnostic reasoning. Academic Medicine, 84(8), 1022-1028.
Kline, J. A., Courtney, D. M., Kabrhel, C., Moore, C. L., Smithline, H. A., Plewa, M. C., Richman, P. B., O'Neil, B. J., & Nordenholz, K. (2008). Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. Journal of Thrombosis and Hemostasis, 6(5), 772-780.
Raja, A. S., Greenberg, J. O., Qaseem, A., Denberg, T. D., Fitterman, N., & Schuur, J. D. (2015). Evaluation of patients with suspected acute pulmonary embolism: Best practice advice from the Clinical Guidelines Committee of the American College of Physicians. Annals of Internal Medicine, 163(9), 701-711.
Wells, P. S., Anderson, D. R., Rodger, M., Ginsberg, J. S., Kearon, C., Gent, M., Turpie, A. G., Bormanis, J., Weitz, J., Chamberlain, M., Bowie, D., Barnes, D., & Hirsh, J. (2000). Derivation of a simple clinical model to categorize patients' probability of pulmonary embolism: Increasing the model's utility with the SimpliRED D-dimer. Thrombosis and Hemostasis, 83(3), 416-420.
How this NU 611 Unit 4 example is structured
In many sections this unit asks for a case based reasoning paper rather than an essay, so the NU 611 Unit 4 example below is written as one; your classroom's instructions decide the exact form. The paper runs in three moves. The first sheet sets out the composite presentation and states the question the visit has to answer, because a differential that is not anchored to a question drifts into a list. The second sheet ranks the candidates by likelihood and by cost of a miss, then argues each one down with a finding that discriminates rather than a finding that merely fits. The third sheet names the decision point, applies the rule that governs it, and states what would have moved the decision the other way.
NU 611 Unit 4 questions, answered
What does the NU 611 Unit 4 assignment usually ask for?
In many sections this unit sits where clinical reasoning is applied rather than introduced, so the work is commonly a case based paper: a presentation, a differential that is ranked, explicit rule outs, and a named decision point with a plan. Your classroom's instructions and rubric decide the exact form, including length, headings, and whether a template is required.
How many diagnoses should the differential carry?
Enough to hold every dangerous cause and the common ones, which for most presentations is five to seven. A longer list rarely earns more credit and often costs it, because each candidate has to be argued down with a discriminating finding. Depth on six well chosen diagnoses reads as judgment; twelve names with one line each reads as a search result.
Can I write about a patient I actually cared for?
Write a composite instead. Build the presentation from patterns you have seen, change every identifier, and never use a real chart, employer, or unit. This paper states that in its opening lines. A composite protects privacy completely and costs nothing academically, because the reasoning is graded, not the provenance of the case.
Write yours, or have the desk draft it
This paper is an original model document written by our desk, not a submitted student paper and not an official Herzing University document. Read it for the moves, then write your own to the instructions in your classroom. If you want one built to your exact prompt and rubric, the first custom sample is free and arrives in 24 to 48 hours.