Prediction of subclavian vein location using plain chest radiography

The relationship between the right subclavian vein and the thoracic inlet below the clavicle was studied by Venography in 72 patients. The area of the thoracic inlet below the clavicle was defined as a radiolucent area surrounded superiorly by the lower border of the clavicle, inferiorly by the inner margin of the first rib and medially by the lateral margin of the manubrium (CRM area). In 10 patients, the subclavian vein was situated below the axis of the clavicle, and the CRM area was large enough to extend near the top of the first rib arch. In 62 patients, the subclavian vein extended above the axis of the clavicle and the CRM area was small or invisible. The existence of a large thoracic inlet below the clavicle (large CRM area which extends near the top of the first rib arch) may be a useful indicator for predicting the low location of the subclavian vein, and may be used to predict or explain venipuncture failure using the standard infraclavicular approach.