The question of whether to drink water before an MRI with contrast is common. The immediate answer is generally yes, though it depends on the specific scan. An MRI with contrast uses a Gadolinium-based contrast agent (GBCA), which is injected into a vein to enhance the visibility of tissues or blood vessels. For most procedures, drinking water is permitted and often encouraged. However, preparation instructions vary significantly, making it necessary to confirm the exact guidelines with the facility performing the scan.
Understanding Pre-Procedure Preparation
Before an MRI with contrast, patients receive instructions that go beyond liquid intake. Solid food fasting is frequently required, usually for four to eight hours before the appointment. This precaution mitigates the risk of nausea or vomiting that some people experience after the GBCA is administered.
If sedation is necessary to help a patient remain still, a stricter fasting protocol is enforced to reduce the risk of aspiration. Patients must remove all metal objects, such as jewelry, watches, and hairpins, because the MRI machine uses a powerful magnetic field. A hospital gown is provided to ensure no hidden metallic items interfere with the imaging or pose a safety risk. Medication patches, such as those containing nicotine or nitroglycerin, must also be disclosed, as some contain metallic components that can heat up during the scan.
Specific Guidelines for Water and Clear Liquids
For many contrast-enhanced MRIs, clear fluids, including plain water, are allowed and sometimes recommended until shortly before the procedure. Staying hydrated can make inserting the intravenous line for the contrast agent easier. Some facilities advise stopping all liquids, including water, only one to two hours before the scan time.
There are important exceptions based on the body area being scanned. Scans targeting the abdomen, pelvis, or specific organs like the liver, pancreas, or gallbladder often require stricter “nothing by mouth” (NPO) rules. This restriction prevents fluids and stomach contents from obscuring the image clarity of the organs under examination. If the procedure requires general anesthesia or deep sedation, liquid intake is often restricted for at least two hours before the scan for safety reasons.
Why Hydration Matters for Contrast Clearance
Hydration plays a role in the body’s management of the GBCA, which the body cannot metabolize. The kidneys filter the contrast material from the bloodstream and excrete it through the urine. Adequate hydration ensures the kidneys can perform this function efficiently.
The majority of the GBCA is eliminated from the body within 24 hours in individuals with normal kidney function. This process is facilitated by maintaining fluid intake, particularly in the hours immediately following the scan. Being well-hydrated before the injection minimizes the stress placed on the kidneys during clearance. Healthcare providers assess kidney function before the scan, especially for older patients or those with pre-existing conditions like diabetes.