When is CTU or IVU contraindicated?
- • CTU and IVU require the administration of an intravenous contrast material and are not performed in patients who have a history of severe adverse reaction to iodinated contrast material
- • Patients with renal insufficiency may have further deterioration in renal function after intravenous iodinated contrast administration. IVU and CTU are best avoided in such patients, and alternative imaging techniques are instead used to evaluate the urinary tract.
- • Pregnancy is a relative contraindication, with the primary concern being radiation exposure to the fetus, particularly in the first and second trimesters of pregnancy. All women of childbearing age are directly questioned to determine the date of the last menstrual period and to ascertain whether the patient could be pregnant. If there is concern, a pregnancy test is obtained before performing the study. If CTU or IVU is unavoidable in a pregnant patient, efforts are made to limit the radiation exposure using the ALARA principle
- • Patients taking oral hypoglycemic agents, such as metformin (Glucophage), should stop taking the medication at the time of CTU or IVU and not resume it until renal function has been confirmed as being normal to avoid the risk of lactic acidosis. Current guidelines do not require the patient to stop taking the medication before contrast administration.