You may make changes online or call to speak with the laboratory draw center you selected. This method requires that you know the confirmation number plus the first and last name of the patient. You may more easily modify your appointment on the confirmation page. This page already has all of your appointment information and allows you to pick a new day and time if your plans change. If you need to pick a different location, then you will need to cancel the appointment and make a new one at a different location.