Contraindications to Internal Jugular Vein Cannulation Absolute contraindications Internal jugular vein thrombosis Local infection at the insertion site Antibiotic-impregnated catheter in allergic patient Relative contraindications Coagulopathy, including therapeutic anticoagulation * Local anatomic distortion, traumatic or congenital, or gross obesity Superior vena cava syndrome Severe cardiorespiratory insufficiency or increased intracranial or intraocular pressure (patients will be compromised by Trendelenburg [head down] positioning) History of prior catheterization of the intended central vein Uncooperative patient (should be sedated if necessary) Left bundle branch block (a guidewire or catheter in the right ventricle can induce complete heart block) * Therapeutic anticoagulation (eg, for pulmonary embolism) increases the risk of bleeding with internal jugular vein cannulation, but this must be balanced against the increased risk of thrombosis (eg, stroke) if anticoagulation is reversed.