The following is intended to serve as a guideline for performing diagnostic studies that require contrast medium. Each case is unique and there will be times when the benefit of information gained from contrast administration will supersede the potential risk of reaction or renal toxicity. The following guidelines may not apply in these cases or in life-threatening emergencies. If contrast media administration is required for a life-threatening diagnosis, then it should not be withheld based on kidney function.
The decision to give IV contrast is often multifactorial, and the clinical scenario is often the most important piece. We want to adhere to the Cr guidelines for outpatients and non-emergent exams wherever possible. However, the Cr guidelines are simply guidelines, and if there is an emergent study that the clinical team feels needs to be done (and requires IV contrast e.g. PE protocol), these guidelines can be over ridden based on the clinical need. It is reasonable to consider an alternative test if it can be safely and expediently done, but we don’t want to delay care and sometimes CT is the best exam in an unstable patient. While we know that acute kidney injury (AKI) or eGFR<30 are the main risk factors for contrast induced AKI, the absolute risk is not clear, may be overstated, and is likely outweighed by the risk of delay in diagnosis in emergent cases. This warrants a conversation with the clinical team about the need and the urgency, but if deemed an emergency without reasonable alternative exam, it is ok to proceed. On the flip side, as we have discussed before, if a study is ordered without IV contrast (but you think it needs it and you don’t see a contraindication), a conversation with the referring team can help clarify the clinical context before making changes to the order or protocol. If you are in doubt, you can always contact the fellow or attending on call (or me if it is a CT/contrast issue) to help.
- A current creatinine level must be available for all inpatients and for outpatients over 6o years of age prior to administration of intravenous contrast. “Current” is defined as within one month for outpatients and within one week for inpatients. Routine ED patients require a same day creatine. Please also reference a complete list of the recommended indications for measurement of serum creatinine (Who must have a creatinine level prior to IV contrast?)
- Patients with an elevated creatinine should receive intravenous contrast only if absolutely necessary. The following table provides a guideline for the use of contrast by type relative to the patients creatinine (mg/dL) or eGFR (%):
UW Guidelines for Contrast Selection
Contrast Creatinine eGFR Iohexol ≤ 1.4 > 50 Iodixanol 1.4 – 1.8 50-40 No Contrast > 1.8 < 40
Contrast Creatinine eGFR Iohexol < 1.8 > 40 Iodixanol 1.8 – 2.4 40-30 No Contrast > 2.4 < 30
- For an acutely traumatized patient for whom there is insufficient time to obtain a creatinine level, it is understood that the benefit of making an emergent diagnosis of a life-threatening injury outweighs the risk of contrast nephrotoxicity.
- Patients who have chronic renal failure and are on chronic dialysis may receive contrast. While the timing of contrast administration is not dependent upon dialysis, it is preferable that the next routine dialysis occurs within 24 hours following contrast. Contrast should be avoided in patients who are experiencing acute dialysis-dependent renal failure as there is hope that renal function will recover. However, contrast may be administered in this setting if the referring physician deems it necessary.
- Patients with multiple myeloma, sickle cell disease, homocystinuria, or active gout may receive intravenous contrast but should be well hydrated.
- Patients who report an allergy-like reaction to contrast may be premedicated according to protocol at the discretion of the radiologist. Resuscitation equipment and drugs should be readily available.
- Patients who report “passing out” or who needed resuscitation after past contrast injections, should have iodinated contrast only if alternative testing will not provide a satisfactory result. Same should apply to patients with allergic asthma or multiple severe allergies.
- Contrast reactions could be potentiated by anxiety. Therefore, if a patient is exceedingly anxious prior to contrast injection, they may be premedicated with: Midazolam, 2 mg IV titrated up to a maximum of 5 mg (contraindication = glaucoma)
Jessica Robbins, June 2015