When preparing a patient for a study of the gallbladder, you should tell the patient to:

General Instructions

Little preparation is needed for a CT scan. Patients, who do not have congestive heart failure or are not on dialysis, are asked to drink 64 ounces of water before the exam, especially if the exam is performed with oral or intravenous contrast. If possible, they should start drinking 12 hours before their scheduled appointment time.

If patient is receiving IV or contrast, they should not eat or drink 4 hours prior to exam.

Patients will be asked to remove jewelry and other metallic objects that might interfere with the scan. We ask patients to leave jewelry at home when possible. 

Patients who are breastfeeding should be given an opportunity to make an informed decision about whether to continue breastfeeding after receiving intravascularly administered iodinated contrast media or to temporarily abstain. A very small percentage of iodinated contrast medium can be excreted into the breast milk and absorbed by the infant’s gut. We believe that the available data suggests that is safe for the mother and infant to continue breastfeeding after receiving such an agent.

The patient can choose to temporarily abstain from breastfeeding for 24 hours with the active expression and discarding of breast milk from both breast during that period. If so, the patient may wish to use a breast pump to obtain milk beforehand to use during the 24 hour period following the administration of contrast media. Please inform the patient of this option when the exam is scheduled. 

Patient Screening Prior to Administration of Iodinated Contrast

Prior to the administration of iodinated contrast, patients are screened for the following:

• Previous reactions to iodinated contrast media
• All severe allergies and reactions (both medications and food)
• History of diabetes, kidney disease, pheochromocytoma, solitary kidney, kidney or other transplant, or myeloma
• Pregnant or breast-feeding (in women of child-bearing age).

Premedication Instructions for Patients with Contrast Allergies

Prednisone 50mg po at 13 hours, 7 hours and 1 hour prior to planned administration of intravenous contrast plus diphenhydramine 50mg po, iv or im at 1 hour prior to planned administration of intravenous contrast

Or

Methylprednisolone 32mg po at 12 hours and 2 hours prior to planned administration of contrast plus diphenhydramine 50 mg po, iv or im at 1 hour prior to the planned administration of contrast

Or

Hydrocortisone 200mg iv at 5 hours and 1 hour prior to planned administration of intravenous contrast if patient is unable to take po medications plus diphenhydramine 50 mg po, iv or im at 1 hour prior to the planned administration of contrast

Creatinine Testing Prior to Contrast Administration

Routine creatinine testing prior to contrast administration is not necessary in all patients. The test should be obtained within 30 days of contrast administration for patients with renal disease, HIV+, diabetic, hypertensive, over 60 years or on chemotherapy. 

Contrast Administration in Patients with Elevated Creatinine

Estimated glomerular filtration rate is a better predicator of renal dysfunction than creatinine alone. The decision to proceed with contrast administration in patients with an estimated GFR < 30 ml/min/1.732 is a matter of clinical judgment, based on the individual circumstances of the patient and following consultation between the radiologist and requesting physician. Strategies to prevent nephropathy in patients with renal impairment include hydration, reduction of contrast dose, and discontinuation of nephrotoxic drugs. A critical diagnostic study should not be delayed because of excessive concern regarding possible contrast nephropathy.        

Contrast Administration in Patients with Renal Failure

Patients on dialysis can receive IV contrast, and early post-procedural dialysis is not routinely required. However, the fact that a patient is on dialysis should not be regarded as automatically allowing the administration IV contrast. The administration of contrast may jeopardize the return of renal function in patients who are receiving dialysis for acute renal failure and may further worsen renal function in patients who still make some urine but receive dialysis intermittently. The volume of IV contrast should also be considered in patients on dialysis who are at risk for volume overload.

Contrast Administration in Pregnant Patients

The iodine content of contrast media has the potential to cause hypothyroidism in the neonate. Pregnant women who receive an intravenous iodinated contrast agent are counseled that neonatal thyroid function should be checked in the first week of life. Informed consent is obtained prior to the administration of contrast in pregnant patients.

You may provide your patients with the following education documents: 

Cardiac Calcium Scoring Only Scan
Computed Tomography (CT)
Computed Tomography Angiography
Computed Tomography (CT) Cardiac

They may also visit VanderbiltHealth.com/radiology.

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