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Morel-Lavallée lesions are closed degloving injuries. They occur when the shearing forces of a high-energy trauma cause separation of the skin and subcutaneous tissue from the muscle fascia. This creates a dead space, allowing blood, lymph, and necrotic fat to collect. Drainage of this fluid is impaired since the vascular and lymphatic supply has been injured. Morel-Lavallée lesions are most commonly seen in the hip or proximal thigh.
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As time passes after the injury, the collection of fluid becomes encapsulated, and this further prevents spontaneous drainage of the lesion. The diagnosis of a Morel-Lavallée lesion is typically made clinically. A swollen area with fluctuance of the soft tissue can be palpated. There may be overlying skin abrasions and ecchymosis. MRI is the most detailed study to characterize these lesions.
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Management and Disposition
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Initial management may be conservative with supportive care and compression dressings. However, once the collection of fluid becomes encapsulated, these patients should be referred to surgery for drainage. Complications of untreated lesions include infection and skin necrosis.
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On bedside ultrasound, these lesions will appear as a homogenous anechoic or hypoechoic fluid collection. However, echogenic foci within the lesion may be seen if fat globules are present.
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