Venography is a radiological examination of the veins using X-rays after injection of contrast medium into the vein via a needle or catheter. Venography is an invasive procedure. This procedure is recommended when the veins need to be clearly demonstrated and or when other methods have been unsatisfactory. Venography can be performed to demonstrate veins of the lower limbs, the upper limbs, in the head and larger veins in the chest or in the abdomen. Venography is most often done to demonstrate veins of the lower limbs to look for blood clots within them and to visualize these veins before surgery or treatment e.g. dissolving blood clots or expanding narrowed areas in abnormal veins. Venography is also useful to evaluate varicose veins as well as other abnormalities of the veins.
The patient may be required to fast for 6 hours before the examination. Venography of the head or organs in the abdomen will require a day of hospital admission, as these examinations are more technically demanding. No anaesthetic or sedation is required as the examination is quite painless, but patient co-operation is needed throughout the examination. Consent from the patient is required prior to the examination. The patient will be required to lie on the x-ray table during fluoroscopy. A needle or catheter will be placed into the vein after a small puncture into the skin. The site of puncture (cannulation) will depend on which veins are to be imaged. Contrast medium is injected into the needle or catheter and X-ray films taken where the veins are demonstrated. The radiologist will then evaluate the images taken. The risks of venography are minimal. There may be a sensation of warmth when the contrast medium is injected into the vein, but this is usually temporary and passes off within seconds. There are no long-term side effects associated with this examination. For punctures involving the groin, bed rest will be advised to ensure that prolonged bleeding does not occur. Patients with history of asthma and any allergies should inform the doctor. If, for example, the patient needs a venogram of the leg, then, any evidence of infection in the region of the leg should be treated first. |