Finding the Balance: The Point-of-Care Ultrasound Diagnosis of Pseudoaneurysm.

A 49-year-old male with history of intravenous drug use presented to the Emergency Department with localized right arm swelling that has been slowly growing for months. On physical exam, there was a golf ball sized mass in the right antecubital fossa without overlying skin changes and no neurovascular deficits in the distal extremity. Point-of-care ultrasound (POCUS) was performed utilizing a water bath with visualization of bidirectional swirling in a round cavity adjacent to the brachial artery. Aneurysms are abnormal focal dilations that result from vascular wall defects. Ultrasound has been reported to have 94% sensitivity and 97% specificity for diagnosis of pseudoaneurysms. On color doppler ultrasound, pseudoaneurysm is characterized by the pathognomonic "yin-yang" sign. In the case of the 49-year-old male with a right antecubital mass and history of IVDU, the proposed mechanism of injury was trauma to the arterial wall secondary to auto-injection. POCUS has been found to improve identification of abscesses and its incorporation in patient evaluation can guide clinical management, prevent unwanted iatrogenic exsanguination, and determine whether there is a need for urgent vascular surgery intervention, particularly in high-risk patients.