Alyssa Lombardi, MS4
Article: Comparison of the Accuracy of Emergency Department-Performed Point-of-Care-Ultrasound (POCUS) in the Diagnosis of Lower-Extremity Deep Vein Thrombosis. Jorge Pedraza García et. al., The Journal of Emergency Medicine, 2018.
Background: DVT/PE affects ~300,000 – 600,000 people in the U.S. each year and is associated with substantial morbidity and mortality. The majority of deaths occur due to PE, most of which originate from DVT in the lower extremity veins. Thus, early and accurate diagnosis of DVT is critical to prevent death and reduce long-term complications. In patients with intermediate to high pretest probability of DVT, compression ultrasound is the diagnostic test of choice. Emergency physicians often use compression ultrasound to evaluate lower extremity DVTs. However, there is controversy in the literature regarding the efficacy of POCUS done by emergency physicians vs. ultrasounds done by radiology departments. The clinical question addressed in this study was the following: how accurate are emergency physicians at using compression ultrasound in the diagnoses of DVT?
The Study:
· Prospective, cross-sectional study completed at Hospital Valle de los Pedroches, Córdoba, Andalucía between March 2012 – May 2014.
· Inclusion criteria: patients >18 years old with suspected DVT of the lower limbs based on signs/symptoms.
· Exclusion criteria: patients with an established diagnosis of DVT, diagnosis of DVT in the past 6 months, recent Doppler ultrasound in the past 30 days, low-risk patients by Wells with a negative D-dimer.
· The 10 emergency physicians involved in the study were required to have at least 5 years experience in the ED after training. These physicians had a 3-day training course in DVT POCUS. All 10 physicians involved had performed > 30 POCUS for DVT prior to this study.
o Three-point compression ultrasound: junction of great saphenous vein and common femoral vein; junction of common femoral, superficial femoral, and deep femoral veins; popliteal vein.
The Results:
· 109 patients underwent a POCUS performed by an emergency physician, followed by a formal radiology Doppler ultrasound performed within 48 hours.
o 49 patients had a negative US in the ED.
§ 45 of these patients had a negative radiology US.
§ 4 false negatives by ED POCUS.
· Occurred in the first 8 months of the study.
· All 4 were popliteal thrombosis in patients with difficult visualization/anatomy.
· Due to large collapsible superficial veins mistaken for deep veins.
o 60 patients had a positive US in the ED.
§ 55 of these patients had a positive radiology US.
§ 5 false positives by ED POCUS.
· 2 cases where a lymph node was misinterpreted as a DVT in the common femoral vein.
· 1 case of a ruptured Bakers cyst misdiagnosed as a popliteal DVT.
· 1 case of superficial thrombophlebitis confused with popliteal DVT.
· 1 case that was admitted with a CTA-confirmed PE. The authors postulated that thrombus embolization might have led to the PE as well as the negative radiology US.
· Emergency physician POCUS in the diagnosis of lower extremity DVT has a:
o Sensitivity of 93.2%
o Specificity of 90.0%
o Test accuracy of 91.7%
o Positive predictive value of 91.7%
o Negative predictive value of 91.8%
o Positive likelihood ratio of 9.32
o Negative likelihood ratio of 0.08
Study Limitations:
· It is unclear what the authors meant by including physicians with 5+ years of experience in the ED after training (what is the training they are referring to?). Details regarding the 3-day DVT POCUS course would be helpful to know as well.
· 48-hour delay between POCUS in the ED and the ultrasound performed by the Radiology Department. This could have affected the ultrasound findings. For example, some DVTs may have embolized; calf DVTs could have progressed to popliteal DVTs.
The Takeaway: This study demonstrated that POCUS in the ED is an accurate method for evaluating for DVTs. Emergency physician-performed compression ultrasound can be done quickly, minimizing treatment delay and length of stay. This study adds to the literature supporting the use of POCUS in the ED to evaluate DVTs. More specifically, this study emphasizes the importance of POCUS training for emergency physicians. Future studies should evaluate the specific length and type of training needed for emergency physicians to adequately use POCUS when evaluating patients for lower extremity DVT.