What is Doppler Ultrasound?
Vascular ultrasound examinations can be a critical diagnostic tool. Although they are more commonly used in non-emergency outpatient settings, they can also be used in urgent care or the emergency room for trauma.
A vascular Doppler ultrasound exam is a type of ultrasound that uses Doppler technology to create color images and videos of what is happening inside the body. This type of ultrasound uses high-frequency sound waves that can show both the direction and speed of blood flow within the veins and arteries.
Vascular Doppler ultrasound exams are often used to diagnose deep vein thrombosis or DVT. DVT occurs when a blood clot forms within the veins, usually in the legs, and disrupts or blocks blood flow. Although this condition can develop over time, it can also be present in trauma situations.
Doppler Ultrasound in Trauma Situations
The vascular system, also known as the circulatory system, comprises the arteries and veins that carry blood throughout the body. In emergencies, vascular injuries can occur due to penetrating or blunt trauma. Penetrating trauma may include gunshot or stab wounds. Blunt trauma may result from fractures, displaced bones, or crush injuries. Vascular injuries can include vein disruption, arterial dissection, and deep vein thrombosis.
Traumatic vascular injuries can be characterized by either ‘hard signs’ or ‘soft signs’. Hard signs of vascular injury include external bleeding or an expanding hematoma (visible internal bleeding beneath the skin). These are usually indications that immediate surgical intervention is necessary. However, soft signs are more difficult to diagnose in a physical exam. Soft signs include reduced pulse or an injury close to a major artery.
A vascular Doppler ultrasound is an accurate, quick, and noninvasive way to help determine if a vascular injury is present. Doppler ultrasound may be used in a trauma situation if the patient is stable and there are soft signs of vascular injury. The benefit of using Doppler ultrasound in place of the gold-standard angiogram is that ultrasound exams are far less invasive.
An angiogram involves injecting a dye into the veins that will show up on an x-ray. By contrast, an ultrasound exam involves using a handheld device (transducer) to gently compress the veins, allowing sound waves to penetrate the vascular system and create images of the veins and arteries.
DVT: Deep Vein Thrombosis
DVT can occur in various parts of the body in a trauma situation, however, in a non-trauma setting, it occurs most often in the legs. In a trauma situation, it is also known as post-traumatic vein thrombosis. In this setting, it can occur minutes or even hours after the initial trauma.
Any blood clot that forms in the veins can be identified via Doppler ultrasound because it will not be easily compressed like other veins without blockages. In addition, blood flow within the affected veins will be greatly reduced or blocked. Since Doppler ultrasound technology can show both the speed and direction of blood flow, this will be evident in the exam results.
In addition to the soft signs of vascular injury, there are symptoms specific to DVT. These include swelling in the leg (or other affected area, usually the limbs), skin that is warm to the touch, and red or bluish discoloration of the skin.
Vascular ultrasound examinations are often used in non-emergency situations, yet they are not used as often in trauma situations to diagnose vascular injuries such as DVT. However, it can be useful to utilize vascular Doppler ultrasound in traumatic situations where only soft signs of vascular injury are present. Ultrasound exams may be preferable to angiograms because they are faster and noninvasive. This can lead to better patient triage and determination if surgical intervention is necessary. Doppler ultrasound can be a life-saving diagnostic tool for serious venous injuries such as DVT.
Guest Contributor: Jordan Galerkin
Sources:
- Deep Vein Thrombosis (DVT). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/deep-vein-thrombosis/symptoms-causes/syc-20352557
- Montorfano, M.A., Pla, F., Vera, L. et al. Point-of-care ultrasound and Doppler ultrasound evaluation of vascular injuries in penetrating and blunt trauma. Crit Ultrasound Journal 9, 5 (2017). https://doi.org/10.1186/s13089-017-0060-5
- Types of Ultrasound. Ultrasound Quotes. https://www.ultrasoundquotes.com/blog/doppler-vs-duplex/
