A major concern with intravenous administration of cytotoxic agents is vessel irritation or extravasation. The Oncology Nursing Society and hospital guidelines require frequent evaluation of blood return when administering vesicant or nonvesicant chemotherapy due to the risk of extravasation. These guidelines apply to peripheral and central venous lines. In addition, central venous lines may be long-term venous access devices. Thus, difficulty drawing or aspirating blood may indicate the line is against the vessel wall or may indicate the line has occlusion. Having the client cough or move position may change the status of the line if it is temporarily against a vessel wall. Occlusion warrants more thorough evaluation via x-ray study to verify placement if the status is questionable and may require a declotting regimen.