Dx: Femoral Artery? Look Again
LN=lymph node superficial to the common femoral vein and common femoral artery
Knowing that the devil is in the details, you ask your resident to describe what we are looking at on the ultrasound image. He states that there is a round, anechoic vascular structure with a hyperechoic clot in the middle. When you ask him to tell you which vessel he saw the clot in, he states authoritatively, “the common femoral vein.” You then ask him to identify where the common femoral artery is on his image. You can almost feel his consternation when he suddenly realizes his mistake. “That’s not a vessel is it?” he asks, as he is begins walking towards the order sheet to cancel his Lovenox order.
After he gracefully explains to the patient what has happened, and palpates the enlarged lymph nodes he saw on his bedside ultrasound, you help your resident repeat the left lower extremity vascular ultrasound. You walk him through how to map out the pertinent vessels and identify the corresponding, adjacent structures. As you scan through the femoral triangle, you help him identify the superficial inguinal lymph node sitting right above the common femoral vein and artery (pictured above).
A quick review of the lower extremity anatomy helps him remember to map out each vessel’s course and you finish your scan by reminding him to obtain both longitudinal and transverse views of the vessel to ensure he is indeed looking at the intended target structure.
One negative DVT study later, your resident has learned a valuable lesson about one of the common pitfalls in bedside vascular ultrasonography, but even more importantly, he has seen that haste can indeed make waste.
Lymph nodes quick guide:
Normal: Size <1cm (<0.5cm for epitrochlear, <1.5cm groin), mobile, non-tender
Reactive: Size <2cm, duration <2wks, soft, tender, may have fever
Cancer: Varying sizes, hard, matted, duration >3wk, weight loss
source: Quick Essentials: Emergency Medicine 4.0
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