Pulmonary Embolism Quiz Answers

1. A 28 y/o female without significant PMH presents c/o one day h/o pleuritic cp. She reports mild sob, no LE edema, no hemoptysis, no prior PE. She is currently on oral contraceptives, but no other medications. Which of the following is true? *

Patients pre-test probability for PE is moderate.

Patient does not require any testing to r/o PE due to a low PERC score.

Answer: A negative d-dimer rules out a PE in this patient.

This patient must have a negative CTPA to rule out PE.

Discussion: The first step to working up PE is to decide whether the patient needs to be worked up. This is a true judgement call, and is not based upon the Wells score or any other scoring method. If PE is on the list and felt to be sufficiently high enough to warrant work up, then you should proceed. This patient is borderline whether she needs to be worked up. If further history revealed cold like symptoms, then a work up would not be needed. If the above were her only symptoms, then a work up would be warranted.
After deciding that the patient needs to be ruled out, the patient is assigned a pretest probability utilizing the Well’s score. This patient Well’s score is zero: No signs or symptoms of DVT; Not the number one list on differential (musculoskeletal would certainly be higher); HR not commented on but assumed <100; No immobility; no hemoptysis; No malignancy. This places her at a low pre-test probability, with only a 3.6% risk of PE. The next step is the PERC score.
The PERC score was designed to rule out patients without doing any testing. It is validated for the ED, not the inpatient setting. Meaning, if the patient is already in the hospital, this score is not validated. If the PERC score is 0, then the patient has been ruled out. If there is even one point, then further testing is warranted. This patient unfortunately does receive one point on the PERC score (oral contraceptives). Further testing is warranted. With a low pretest probability, a negative high sensitivity d-dimer would rule out PE.

2. A 49 y/o male with PMH for CHF presents c/o a three day h/o sob, doe, and LE edema. On physical exam he is noted to have a HR of 105, BP 167/98, and RR22. He has JVD, elevated JVP, diffuse rales, and 2+ pitting edema. The ED checks a cxr and labs. The cxr show bilateral effusions. The d-dimer is positive. *

The patient has a moderate pretest probability for PE.

A CTPA must be ordered to rule out a PE in this patient.

Answer: PE does not need to be ruled out in this patient.

The patient should be give lovenox until PE has been ruled out in the patient.

Discussion: This patient clearly has acute decompensated heart failure. Massive PE can lead to cor pulmonale, but not to left heart failure. With the diagnosis already made, the first question of whether PE needs to be ruled out is negative. A well’s score should not be calculated! Remember, the Well’s score does not help decide if the patient should be worked up or not. All patients with CHF, pneumonia, or any pulmonary condition will have at least a moderate pretest probability. This does not mean they need to be worked. If a diagnosis is clear, and there is not anything else to raise concern, PE does not need to be pursued.
It is fairly common to be encountered with the positive d-dimer when one was never desired. D-dimer is used only to rule out a PE (or DVT). A positive d-dimer means nothing if PE is not being worked up. For this reason, the d-dimer should be ignored. It has a terrible specificity, and many people will have positives. Positive d-dimers do not warrant work up if PE is not being pursued!

3. 67 y/o female with PMH CHF, h/o breast cancer in 2005 presented with severe sob that had started suddenly earlier in the day. No hemoptysis, no cough, no fever, no chills, no recent travel. Physical exam shows HR 108, BP 108/56. Lungs clear. Cxr negative.

A negative CTPA rules out PE in this patient.

This patient should be empirically started on lovenox (40 units SC daily) until PE has been ruled out.

Answer: Positive LE dopplers would rule in a PE in this patient.

A negative d-dimer would not rule out a PE in this patient.

Discussion: This patient clearly needs to have PE ruled out. The Well’s score is 4.5, placing her at a moderate pretest probability (cancer only counts if it has active been within the last 6 months). Moderate pretest probability places her at a 20.5% chance of having a PE, high enough to warrant empiric treatment. Lovenox (enoxaparin) is a low molecular weight heparin and would be the treatment of choice at The Christ Hospital, if no contraindications (GFR <30, weight >150kg). The dose is 1 mg/kg sc q12 hour. The 40 mg sc daily is the prophylactic dose, not treatment dose. This patient warrants treatment dose.
Ruling out a PE on a patient with moderate pretest probability requires either a negative high sensitive d-dimer or a negative CTPA AND negative LE doppler. A positive result in either the CTPA or doppler rules in a PE. CTPA’s are not 100% sensitive, with a negative CTPA having a 89% negative predictive value (NPV). To rule in or rule out a PE, the NPV or PPV needs to be over 90%.

4. 79 y/o male without significant PMH presents with mild sob. Denies cp, no hemoptysis. +cough, +congestion, +mild fevers. Wife has "cold". Physical exam: HR 91 BP: 108/50 O2 Sat: 98% on RA. Lungs have rhonchi. Cxr is negative. *

A positive CTPA (subsegmental) would rule in a PE in this patient.

To rule out a PE this patient would need a negative CTPA and le doppler.

Answer: This patient does not need to be ruled out for a PE.

If the patient has a positive d-dimer, a CTPA must be ordered.

Discussion: This patient does not require any work-up, clearly having a cold leading to costochondritis. The first option is a situation that arises occasionally. It is not uncommon to see a patient get a CTPA who may not really have needed it. In the first option, the patient got an unnecessary CTPA which returned as positive! The first step is to find out where the PE was positive. When dealing with the smaller vessels, it can be very difficult to say whether there is a filling defect or artifact. If it was felt the patient needed to be worked up, his Wells score would be 0 and he would have a low pretest probability. The positive predictive value for a patient with a positive CTPA depends upon the location of the possible PE: Subsegemntal 25%; Segmental 67%; Main or lobar: 97%.
This patient had a positive subsegmental CTPA. He is much more likely to not have a PE than to have a PE!! To rule him out at that time, he would need a negative pulmonary angiogram! This can be a very difficult situation as you can imagine!

5. A 57 y/o male presents to the ED with cp and sob. Utilizing the Wells score, the patient is assigned a high pretest probability for PE. Which of the following is true?

A negative d-dimer rules a PE out.

Answer: The patient should be started on lovenox (1mg/kg sc q12 hour) with first dose stat.

A negative CTPA rules out a PE.

A negative CTPA and negative LE dopplers rule out a PE.

Discussion: High pretest probability for PE places the patient at a 66.7% chance of a PE! Clearly high enough to warrant empiric treatment. Lovenox (enoxaparin) is the treatment of choice, with dose of 1mg/kg sc q12 hour. It is very important to always write q12 hour, with the first dose stat. If 1mg/kg sc bid is written, the first dose will be at 9pm or 9am depending upon when written. This can leave patients without any treatment for several hours.
D-dimer can not rule out PE in a patient with high pretest probability, infact only a pulmonary angiogram can rule a patient out with a high pretest probability! A negative CTPA has a NPV of 62%. Negative CTPA and negative dopplers only push the NPV to 82%. To rule out PE, the NPV must be over 90%.