Venous Doppler is an ultrasound imaging test to the arms and legs in order to check for disruption of flow of blood in the veins due to thrombosis. It is a non-invasive procedure that does not need any special preparations, except informing the patient to avoid cigarette smoking few hours before the test. Cigarette smoking may alter results of the test. Discontinuing of any medication is not indicated for Venous Doppler examination. NPO orders are usually instructed to patients scheduled for blood analysis, while force fluid preparations are for those who will undergo abdominal and pelvic ultrasound.