A Gastric Emptying Study (GES) is a specialized nuclear medicine procedure that measures the speed at which food leaves the stomach and enters the small intestine. This process, known as gastric motility, is tracked using a specialized camera after consuming a meal containing a small, safe amount of radioactive tracer. The most common protocol, the solid-phase study, requires an on-site commitment of approximately four hours. This duration is necessary to capture precise measurements at specific intervals, though the patient is not actively undergoing scanning the entire time. The study helps physicians diagnose conditions like gastroparesis (delayed emptying) or dumping syndrome (rapid emptying).
Necessary Preparation Steps
Preparation for the study focuses on standardizing stomach conditions to ensure accurate results. You must fast for a minimum of four to six hours before the procedure, often requiring an overnight fast. This ensures your stomach is completely empty when the test meal is consumed, establishing a true baseline.
It is important to review all current medications with your physician several days before the test, as many common drugs can interfere with gastric motility. Medications that affect stomach emptying, such as opioids, prokinetics, and certain antidepressants, often need to be temporarily stopped. Patients with diabetes must control blood glucose levels, ideally remaining below 200 mg/dL, because high blood sugar can slow stomach emptying and skew results. Failing to follow these instructions may lead to the cancellation of the study or inaccurate findings.
Understanding the Standard Four-Hour Timeline
The standard protocol for a solid-phase gastric emptying study uses a precise four-hour measurement window. The process begins with consuming a standardized, low-fat meal, typically scrambled egg whites mixed with the radioactive tracer, served on toast with jelly and water. This meal must be eaten entirely within ten minutes to ensure a consistent starting point. The tracer labels the solid food so the camera can track its movement.
Immediately after eating, the first image, known as the zero-hour scan, establishes the initial amount of tracer activity in the stomach. The remaining time is structured around three subsequent brief scanning sessions. These interval scans are performed at the one-hour, two-hour, and four-hour marks after meal ingestion.
During the intervals between imaging sessions, you are permitted to move around, but you must remain at or near the facility. Staying on-site ensures you are available to return to the camera precisely at the scheduled times. The final image at the four-hour mark is the endpoint for assessing the stomach’s ability to process solid food.
Factors That Alter Study Duration
While the solid-phase study uses a four-hour timeline, other protocols can significantly change the total duration. Studies focusing only on liquid emptying are much shorter, often lasting 90 minutes to two hours, because liquids empty faster than solids. If a physician needs to assess both liquid and solid emptying, a dual-phase study is performed, which may involve two different tracers and still adheres to the four-hour solid meal timeline.
In cases where initial results are inconclusive or the patient exhibits unusually slow emptying, the physician may order an extended study. This extended protocol requires additional imaging sessions at five or six hours post-meal to confirm severe delayed emptying. Protocols for pediatric patients or those with certain surgical histories may also be modified.
Receiving and Interpreting the Results
Once the final image is captured at the four-hour mark, the study is complete, and you are free to leave the facility and resume normal activities. The images captured by the gamma camera are not interpreted immediately. Instead, the raw data must be analyzed by a nuclear medicine physician.
This specialist calculates the percentage of the tracer-labeled meal remaining in the stomach at each time point to determine the gastric half-emptying time. The nuclear medicine physician compiles these details into a formal report, which is sent to the referring physician. Your referring physician interprets the findings—whether your emptying rate is delayed, normal, or rapid—and discusses the implications and necessary treatment options with you.