Purpose or Case Report: Background: Hemophilia is a rare X-linked recessive bleeding disorder characterized by the absence of one of the coagulation factors including factor VIII in hemophilia A and factor IX in hemophilia B. Amongst the complications, muscle hemorrhage is the second most common type of hemorrhage in hemophilia, second only to hemarthrosis. Bleeding may be precipitated by trauma or fractures or may be spontaneous. Hemorrhage into the large muscle groups of the upper and lower extremities, can cause tissue compartment syndrome, nerve compression, and potential tissue death. A child with hemophilia and muscle hemorrhage may present with focal swelling, pain, or refusal to use the affected body part. Early recognition and treatment of muscle hemorrhages can prevent compartment syndrome and longterm complications, reduce pain, and allow a quick return to normal function and activity.
Aims:
1. To describe utility of rapid ultrasound in detecting muscle hemorrhages in children with hemophilia.

2. To illustrate sonographic appearances of muscle hemorrhages in various locations in the body.
Methods & Materials: US exams performed for suspected muscle bleed in children with hemophilia were retrospectively reviewed. The presence or absence, location and distribution of muscle hemorrhages was studied. Correlation was made with other available imaging and clinical/ laboratory findings.
Results:
Common sites of muscle hemorrhage are iliopsoas, quadriceps, gastrocnemius, gluteal, forearm flexors and sometimes the sternomastoid muscle in the neck. In the acute phase, a muscle bleed is seen as an area of heterogeneously increased echogenicity in the involved muscle, which becomes hypoechoic as time passes. Asymmetric enlargement of the muscle belly is helpful to pinpoint the involved muscle. Complications of muscle hemorrhage can range from stiffness, muscle atrophy, decreased flexibility, and in extreme cases, limb loss. Timely diagnosis of muscle bleed is essential for optimal management.
Conclusions: Through this exhibit, participants will learn to utilize rapid ultrasound as an effective tool to detect muscle bleed, and gain familiarity with the sonographic appearances of muscle hemorrhage in various locations in the body. Apart from demonstrating the extent of muscle hemorrhage, ultrasound can aid in detecting superadded infection and provide guidance for aspiration and drainage.