Venous system

Published on 12/06/2015 by admin

Filed under Radiology

Last modified 12/06/2015

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Venous system

Peripheral venography

Intravenous (i.v.) peripheral venography is an invasive procedure requiring i.v. injection of contrast medium and the use of ionizing radiation. Marked limb swelling can result in failure to cannulate a vein which precludes use of the technique. False-negative results do occur. It is still considered the gold standard for diagnosis of deep venous thrombosis, but is now only very rarely performed.

Lower limb

Technique

1. The patient is supine and tilted 40° head up, to delay the transit time of the contrast medium.

2. A tourniquet is applied tightly just above the ankle to occlude the superficial venous system. The compression may also occlude the anterior tibial veins, and so their absence should not automatically be interpreted as due to venous thrombosis.

3. A 19G butterfly needle (smaller if necessary) is inserted into a vein on the dorsum of the foot. If the needle is too near the ankle, the contrast medium may bypass the deep veins and so give the impression of deep venous occlusion.

4. 40 ml of contrast medium is injected by hand. The first series of spot films is then taken.

5. A further 20 ml bolus is injected quickly whilst the patient performs a Valsalva manoeuvre to delay the transit of contrast medium into the upper thigh and pelvic veins. The patient is tilted quickly into a slightly head down position and the Valsalva manoeuvre is relaxed. Alternatively, if the patient is unable to comply, direct manual pressure over the femoral vein whilst the table is being tilted into the head-down position will achieve the same effect. Films are taken 2–3 s after releasing pressure.

6. At the end of the procedure the needle should be flushed with 0.9% saline to lessen the chance of phlebitis due to contrast medium.

Central venography

Superior vena cavography