Colour Doppler Ultrasound
Doppler ultrasound uses reflected sound waves to evaluate blood as it flows through a blood vessel. It helps to evaluate blood flow through the major arteries and veins of the arms, legs, and neck. Assessment of partial or fully occluded blood flow is possible . Doppler is also used to reveal blood clots in leg veins.

During Doppler ultrasound, a handheld instrument (transducer) is passed lightly over the skin above a blood vessel. The transducer sends and receives sound waves that are amplified through a microphone. The sound waves bounce off solid objects, including blood cells. The movement of blood cells causes a change in pitch of the reflected sound waves (called the Doppler effect). If there is no blood flow, the pitch does not change. Information from the reflected sound waves can be processed by a computer to provide graphs or pictures that represent the flow of blood through the blood vessels.

The types of Doppler ultrasound are:

• Duplex Doppler. Duplex Doppler ultrasound uses standard ultrasound methods to produce an image of a blood vessel and surrounding organs. In addition, a computer converts the Doppler sounds into a graph that provides information about the speed and direction of blood flow through the blood vessel being evaluated.
• Colour Doppler. Colour Doppler uses standard ultrasound methods to produce an image of a blood vessel. In addition, a computer converts the Doppler sounds into colours that are overlaid on the image of the blood vessel and represents the speed and direction of blood flow through the vessel.
• Power Doppler. Power Doppler is a newer ultrasound technique that is up to five times more sensitive in detecting blood flow than colour Doppler. Power Doppler can obtain some images that are difficult or impossible to obtain using standard colour Doppler. However, power doppler is most commonly used to evaluate blood flow through vessels within solid organs. Blood flow in individual blood vessels is most commonly evaluated by combining colour doppler with duplex doppler. Together, they are able to provide better information on the direction and speed of blood flow than when these techniques are used individually.

Key Indications for Doppler Ultrasound:
Indications include:.

• Stroke: Detection of stenotic disease of the extracranial carotid and vertebral arteries.
• Renovascular hypertension : Doppler examines the main renal arteries, intrarenal arteries and renal veins to detect cause of hypertension.
• Arterial Bypass Grafts: Regular (6-12 monthly) examination of these grafts is essential to enable early detection of graft failure. This allows timely graft revision.
• Varicose Veins: Used for venous incompetence and post phlebitic syndrome. Varicose vein mapping and marking can be performed pre operatively to assist the surgical procedure.
• Musculoskeletal scanning : evaluation of traumatic degenerative inflammatory and neoplastic pathologies.

We welcome discussion with our Radiologists - please call us to discuss queries on assessment of speciific clinical needs.

			Pre Examination
	Your patient will require an appointment .  Doppler ultrasound is offered at specific locations Please contact your local practice and the reception staff will give you the nearest site for your patient. There is no special preparation for this scan.

			The Examination
	On average the scan takes 40-60 minutes. The scan will be performed by either a Radiologist or a Sonographer.

			Post Examination
	After the scan the Radiologist will send a report to your referring Specialist or General Practitioner . The images will be sent to the patient unless you request otherwise.