A Simple Method for Lower Extremity Phlebography—Pseudo-Obstruction of the Popliteal Vein

Abstract

Lack of consistent deep venous filling has been a shortcoming in phlebography of the lower extremity. Certain measures commonly adopted to improve phlebographic examination have included tourniquet placement about the ankle, internal rotation of the leg, serial filming, and biplane examination. The use of higher doses of contrast medium has been helpful only when the examination is performed in the erect position (3). Performance of the examination in the erect position is the only maneuver which has reportedly resulted in consistently good visualization of the deep venous system (4). This was pioneered by Lindblom (5), who felt that the poor visualization of the deep veins in the horizontal position was due to sedimentation of the contrast medium since it is heavier than blood. Greitz (3) showed that the effect was due to a lack of mixing rather than sedimentation and found that a position 65° from the horizontal was as successful as the vertical. Phlebography in the erect or semierect position is not without its disadvantages. DeWeese and Rogoff (2) reported a 10 per cent incidence of syncope in their series. Needle placement is jeopardized by assumption of the erect position, particularly since exercise is necessary for consistent visualization of the deep veins in the thigh in this position. Surgical exposure and cannulation of the vein may then become necessary for optimum success, and yet in some patients, especially those with acute thrombophlebitis, both exercise and surgical exposure may be contraindicated. Serial filming is of value in the phlebographic examination. Film-changing, however, especially when 14 × 36-inch cassettes are used, is difficult with the patient erect or semierect. Lastly, a biplane examination with turning of the patient is cumbersome when he is erect. Horizontal or near-horizontal position is more suitable for phlebography of the lower extremity, provided adequate deep filling can be obtained routinely. Extrinsic myofascial and∕or osseous compression of the popliteal vein is probably responsible for poor deep venous filling and appears to be related to positioning. For example, in patients placed in circular casts, edema or thrombophlebitis frequently develops when the leg is in full extension. Casting the leg with the knee in slight flexion serves to avoid this complication. Furthermore, rupture of plantaris tendon or muscle by forceful hyperextension is frequently followed by edema and occasionally by thrombophlebitis. It has also been noted during surgical exposure of the popliteal vein that after forceful extension of the leg and dorsiflexion of the foot the popliteal vein is obstructed by the soleus bridge. Lateral phlebograms taken with the leg extended have shown compression of the popliteal vein at the level of the condyles of the femur.