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Beyond the well-known primary and secondary indications for emergency ultrasound lie a plethora of clinically useful soft tissue ultrasound applications. These offer the emergency care provider the ability to rapidly evaluate and better manage a wide array of common clinical problems. This chapter will focus on eight areas where the use of these soft tissue techniques can be of considerable value in the care of the emergency or ambulatory care patient. These include (1) evaluation of abdominal wall masses, (2) miscellaneous applications for the airway, (3) assessment of bony cortices for rapid fracture diagnosis, (4) foreign body localization, (5) imaging of tendons, joints, and muscles, (6) diagnosis of salivary gland disease, (7) bedside detection of maxillary sinusitis, and (8) evaluation of soft tissue infections, particularly for detection and accurate localization of subcutaneous abscesses prior to drainage.
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Clinical Considerations and Indications
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A surprisingly wide range of pathological processes can occur in the abdominal wall and a patient's abdominal pain may, on occasion, be discovered to be 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 bedside 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, or is fluid collection present? Is a fascial defect present in the abdominal wall, and if so, is a loop of bowel seen passing through the defect? Armed with this additional anatomic knowledge, the site of the findings, and the history, the provider can then pursue a more targeted work-up of the abnormal process at hand.
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Incisional hernias are said to occur as a delayed complication in up to 4% of abdominal surgeries1 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 always be found along the lateral border of the rectus muscle and a focal defect will be present in the aponeuroses of the transversus abdominus and internal oblique muscles but not in the aponeurosis of the external oblique muscle. Since the fascial defect lies beneath the external oblique aponeurosis, the defect ...