There are no serious preparations that one needs to perform when undergoing a Voiding Cystourethrogram (VCUG) by SMIL, although you should make it a point to empty your bladder before the test.
You should inform your radiologist of any medications you are taking and if you have any allergies, especially to barium or iodinated contrast materials. Also inform your radiologist about recent illnesses or other medical conditions.
You may be asked to remove some or all of your clothes and to wear a gown during the exam.
Women should always inform their radiologist and x-ray technologist if there is any possibility that they are pregnant.