Venography is a radiologic procedure used to image the venous system, specifically the veins of the legs. In most cases, the indication arises from suspicion of thrombosis or varicose veins. Because of the radiation and contrast agent exposure of venography, sonography is increasingly used as an alternative for imaging veins.
What is venography?
Venography is a radiologic procedure used to image the venous system, specifically the veins of the legs. The term venography refers to the procedure of phlebography. This is a diagnostic radiological procedure that images veins and allows the physician to evaluate venous structures. Phlebography takes place within the field of phlebology and is one of the most informative diagnostic tools for detecting thrombi. Especially in cases of suspected leg vein thrombosis, the procedure of venography is used. The visualization of the individual veins is made possible by the injection of X-ray contrast medium, which is usually given into the superficial epifascial veins. In the radiological diagnostic procedure, functional images take place in differently applied time windows, which allow for an all the more detailed assessment of the venous system. The procedure is rarely used on larger vena cavae of the upper body. As an alternative to venography, sonography can take place, which is used more frequently than radiation venography, especially on veins of larger caliber.
Function, effect, and goals
Leg phlebography is the most common venography. To perform the examination, a tourniquet, also known as a tourniquet, is placed over the ankle area of the standing patient. In order to image the veins, the patient is injected with contrast material into a vein in the back of the foot. After the contrast is administered, x-rays are taken of the leg, also known as target images. In arm phlebography, the examiner proceeds analogously to the procedure described. The assessment of X-ray images is therefore particularly used in cases of suspected thrombosis, because thromboses are expressed in the images as contrast medium recesses within the course of the vessel. Thromboses are blockages due to blood clots and can be clearly identified using venography. During the course of the procedure, venography produces what is known as a phlebogram, which can provide the physician with indications of thrombosis as well as signs of varicose veins and even their causes. In most cases, venographic examinations are used within medicine in combination with other examination procedures, such as complementary to them or in addition to them. Sometimes most frequently venography is combined with duplex sonography, so especially in case of resultless duplex sonography. Although veins can now be imaged by less stressful procedures, venography still has its advantages, especially in branched and thin veins of the lower leg or forearm. The procedure also offers advantages in more complex varicose veins or in patients with postthrombotic syndrome. The method also has advantages over other methods for imaging venous valves. Since venography is still associated with the most reliable information, it is often used for varicose vein surgery and its preparation. Only in rare cases, phlebography is performed on the great vena cava in the area of the upper body. The same is true for the abdominal region. The technique used here is similar to that just described, but usually requires larger amounts of contrast medium and higher flow rates. This variation of the procedure is often referred to as upper or lower cavography. However, this variant of venography has now been almost completely replaced by computed tomography and magnetic resonance imaging, since both procedures provide significantly more additional information at approximately the same levels of stress on the organism. The greatest advantage of phlebography is considered to be the complete visualization of branched or complex venous systems, which can be performed over a longer distance. In addition, venography enables the pictorial documentation of functional peculiarities, as they may occur during movements of the extremities or during a change in position in the venous system.
Risks, side effects and dangers
As a radiologic procedure, venography is associated with some risks and side effects. These include, for example, the radiation exposure that patients must undergo during the procedure. Meanwhile, this exposure is extremely low and only rarely has actual consequences. A somewhat higher risk is associated with the injection of contrast medium, which can cause allergies. Sometimes the most common side effect of contrast media is headache and nausea. After contrast agent administration, the patient is encouraged to take in plenty of fluids on the same day, thus flushing out the agent as quickly as possible. If contrast medium remains in the body for too long, it puts a strain on the kidneys in particular. Venography also has a number of disadvantages for the institution performing the procedure, most notably the costly and location-dependent equipment and the need for specialists with radiological experience. For this reason, modern alternatives, such as sonography, are now often preferred for the evaluation of veins. Thrombosis can be ruled out or confirmed using this less stressful procedure. For large-caliber veins, MRI is also frequently used, although this is similarly stressful for the patient. For all other veins, duplex color Doppler sonography is now most commonly used, as this method does not involve radiation or contrast agent exposure for the patient. While sonographic procedures can usually be performed on an outpatient basis, procedures such as MRI, CT, or venography often require the patient to be admitted to the hospital.
