What happens
A cannula is placed in a vein, usually in the arm, before or during the exam. The first pictures are often taken without contrast. The injection follows, then more pictures. You stay on the table. The extra time is usually 10–15 minutes, not a second appointment.
What it feels like
The injection is briefly cold. A metallic taste happens to some people and passes. Staff stay in contact. Tell them at once if you feel itchy, short of breath or unwell. Serious allergy is uncommon. The clinic is equipped for it.
You can normally eat afterwards and return to your day, unless you were given a sedative. Drink water if the clinic suggests it. Kidney advice, if it applies to you, should already have been handled before the injection.