Beyond the well-known primary applications of emergency ultrasound lies a veritable smorgasbord of clinically useful ultrasound applications. Some of these applications allow emergency care providers to rapidly evaluate and better manage common clinical problems. This chapter will focus on eight applications of point-of-care ultrasound that are useful in the acute care setting. These include (1) evaluation of abdominal wall pain and masses; (2) airway assessment; (3) evaluation of bony cortices for rapid fracture diagnosis and postreduction alignment; (4) subcutaneous foreign body diagnosis and localization; (5) imaging of selected tendons, joints, and muscles for common musculoskeletal complaints; (6) diagnosis of salivary gland disease; (7) point-of-care detection of maxillary sinusitis; and (8) evaluation of soft tissue infections, particularly for detection and accurate localization of subcutaneous abscesses prior to drainage.
Clinical Considerations and Indications
A surprisingly wide range of pathologic processes can occur in the abdominal wall, and a patient's abdominal pain may, on occasion, be discovered due to a lesion or defect within this anatomic region. Since the area of anatomic interest is quite superficial and free of shadowing artifacts, it is well suited to sonographic evaluation with a linear array transducer. When a palpable or indistinct abdominal wall mass is found on physical examination, or when a focal area of abdominal wall tenderness is encountered, a point-of-care ultrasound examination of the affected area may help provide immediate answers to a number of clinical questions. Is the region of tenderness due to a lesion within the abdominal wall itself or does it appear that an underlying structure (e.g., a metastatic lesion in the liver) is causing the discomfort? If a lesion is present, where is it and what are its sonographic characteristics? Is it solid, cystic, hypo, or hyperechoic, and is it a vascular structure? Is a fluid collection present, and if so, is the fluid simple or complex? Is a fascial defect noted in the abdominal wall, and if present, is a loop of bowel seen passing through the defect? Armed with the additional anatomic knowledge of the site and character of the sonographic findings, as well as the clinical history, the provider can then pursue a more targeted workup.
Ultrasound examination of the abdominal wall can provide valuable information when the diagnosis of an abdominal wall hernia is unclear. In one clinical series, 39% of 144 patients with an abdominal wall mass of unclear etiology (with or without pain) were found to have a hernia.1 Incisional hernias occur as a delayed complication in up to 4% of abdominal surgeries2, and ultrasound can sometimes detect the fascial defect early in its development. While many abdominal wall hernias are apparent on clinical examination alone and do not require sonographic evaluation for diagnosis, others can be difficult to diagnose because the fascial defect is small and difficult to appreciate clinically. The fascial defect in a Spigelian hernia (also known as an interstitial hernia) will be found ...