Unusual Evidence of Fat Embolism in the Subclavian Vein Detected by High-Intensity Transient Signals

Abstract

Fat emboli may occur in patients after traumatic fractures or orthopedic procedures; however, their clinical detection is a very rare finding. Here, we describe a 77-year-old female who was admitted to the emergency department with a fracture of the right humerus. We diagnosed fat embolism after an ultrasound of the right subclavian vein. The embolism was detected by high-intensity transient signals present on the spectral Doppler. While these signals are well known for microembolization in transcranial Doppler, to our knowledge this is the first case report in the medical literature to observe and describe high-intensity transient signals seen in the upper extremities by spectral Doppler. Although it is unusual to detect a fat embolism in transit, we believe clinicians should be aware of this finding, particularly when evaluating high-risk patients.

Keywords: fat embolism; fat embolism syndrome; high-intensity transient signals; spectral Doppler; subclavian vein; venous duplex ultrasound.

Figure 1

Venous duplex ultrasound of the right subclavian vein. (A) The rhomboid box illustrates the color Doppler showing blue blood flow without any visible clot. (B) Spectral Doppler (Zoom) shows multiple high intensity transient signals representing fat microemboli (denoted by yellow arrows).

Figure 2

Venous duplex ultrasound of the left subclavian vein. Doppler image demonstrates normal blood flow and no detection of high intensity transient signals in the spectral Doppler.