Non infected seromas after surgery are usually anechoic collections. Fluid collections complicated by infection or hemorrhage appear more complex, with ariable degrees of internal echoes, layering, and septa (Figure 2 ).

• 术后未感染的血清肿常为无回声的积液，并发于感染或出血的积液其表现比较复杂，内部回声程度、分层和分隔常不同（图2）。