This was a terrific pick up and the formal echo performed agreed with the moderate sized pericardial effusion without evidence of tamponade physiology. Since she also had a malar rash with the echo finding, she was worked up and newly diagnosed with lupus during her hospitalization.
This case underlines the utility of looking with ultrasound with any suspicion of cardiomegaly (especially when it is a new finding). We encourage you all to try a subxiphoid or parasternal view to quickly assess for pericardial effusion.
It's also important to remember the differentiation between pericardial effusion and epicardial fat pad (a very common cause of false positives). The fat pad will NOT be circumferential and will almost always be located anterior to the RV and not present posterior to the LV. It should also be echogenic (a shade of gray) and move with ventricular activity. In contrast, a true effusion will be an anechoic (dark/black) area of fluid between the myocardium and the pericardium (which is hyperechoic – bright white) and it will usually be circumferential.
If you see anything suspicious, always confirm it with a different view (parasternal long, parasternal short, subxiphoid or apical). And remember you need three views to get credit for an ED echo towards your credentialing.
Please feel free to email me with any thoughts/questions: email@example.com.