Occlusion of the line may occur for a variety of reasons: catheter thrombosis, medication precipitate, fibrin sheath formation, catheter tip resting against the wall of the vein, and failure to use positive pressure. To prevent occlusion, always assess catheter patency prior to administering any medication or fluid, flush the catheter a minimum of once weekly and following each use, and use the positive pressure technique when heparinizing the catheter to prevent reflux of blood into the catheter tip.

If occlusion does occur:

1. Ask the patient to change positions, raise their arms, and/or cough repeatedly in order to shift the position of the catheter from the wall of the vein
2. Attach a 10mL syringe with 3mL NaCl 0.9% to the catheter. Attempt to withdraw a possible clot by pulling and then releasing on the plunger. Never inject any solution into the catheter when patency is not clearly established. Continue with the previous interventions
3. Fluoroscopy may be performed to determine the presence of a fibrin sheath or a thrombus

Fibrin or clots may be dissolved using Urokinase (5000 IU/mL) instillation into the catheter.  This procedure is typically performed by IVR.