Written by Zach Adams, OSU EM resident // Edited by Michael Barrie EM Assistant Professor.
Bottom line: D-dimer reliably excludes PE in low/moderate risk patients, however use clinical history/exam to guide pursuing advanced imaging.
An otherwise healthy 23 year-old presents with worsening shortness of breath for the past 7 days. Shortness of breath began suddenly while at rest, has been continuous, and with associated reduced exercise tolerance. Five days ago she was seen in the ED with a negative d-dimer and CXR and discharged with return precautions. Since then, she states that the symptoms have progressed. She says she cannot lie flat. ROS reveals a history of antecedent URI 10 days ago. She is a non-smoker, takes no birth control pills, does not have a personal or family history of DVT or PE, and denies recent prolonged travel. She appears uncomfortable and takes deep inspirations every 3-5 seconds. Her physical exam reveals tachypnea with otherwise normal exam. ECG shows normal sinus rhythm. CXR is normal and repeat d-dimer is negative.
The patient has bounced back with worsening symptoms. I struggled with this clinical question: should we obtain a CT PE to rule out PE despite a negative d-dimer in this low risk patient?