Fat embolism syndrome (FES) is most often associated with orthopedic trauma that typically presents 24-72 hours after the trauma with a classic triad. Only few cases of fat embolism due to lower extremity venous system had been reported. The current case report presents a pregnant woman who was referred to our emergency department with bilateral femoral open fracture. After detecting fetal demise by abdominopelvic ultrasound, an area of fat density in right external iliac vein was detected in abdominopelvic contrast enhanced computed tomography (CT) scan which was considered as the probable diagnosis of fat embolism. While the patient did not show signs and symptoms of FES, the fat embolism was confirmed in further evaluations. In summary, although detection of fat embolus in CT scan in the emergency department is very rare, evaluation of lower extremity venous system in a posttraumatic patient seems to be crucial because early diagnosis of fat embolism can help the clinicians to prevent FES.