A groin hematoma occurs when blood leaks from an artery, typically the femoral artery, and causes localized swelling. Some risk factors can include recent procedure in that area, obesity, anticoagulation, and peripheral vascular disease (Kosmidou & Karmpaliotis).
On ultrasound, a groin hematoma will be hypoechoic with some anechoic areas scattered throughout. If you scan the hematoma in the longitudinal view, it becomes obvious that the object is circumscribed and not tubular like a vein or artery.
