The stomach’s ability to efficiently move food into the small intestine is a fundamental process of digestion. This controlled movement, known as gastric emptying, ensures that nutrients are properly broken down and absorbed by the body. When this process is too fast or too slow, it can lead to uncomfortable and sometimes debilitating digestive symptoms. The Gastric Emptying Study (GES) is the established medical procedure used to accurately measure this rate of movement.
Understanding the Gastric Emptying Study
The Gastric Emptying Study (GES), or scintigraphy, is a non-invasive test that measures how quickly solid food leaves the stomach and enters the duodenum, the first part of the small intestine. This measurement provides physicians with objective data on the stomach’s muscular function. Doctors typically order this study to investigate persistent symptoms such as chronic nausea, vomiting, unexplained early fullness after eating, or abdominal pain.
The mechanism relies on nuclear medicine techniques. A specialized camera detects a harmless radioactive marker mixed into the meal, quantifying the percentage remaining in the stomach at various times. This quantitative approach helps differentiate between functional motility issues and structural problems. The study focuses primarily on solid foods because their emptying rate is more sensitive for detecting motility disorders than liquids.
The Procedure and Timing Intervals
The study begins with the patient fasting for a minimum of six hours, usually overnight, to ensure the stomach is empty before the test meal. Patients must temporarily stop taking certain medications that influence gut motility, such as narcotics or specific antispasmodics, which could skew the results. This preparation standardizes the stomach’s environment, allowing for an accurate baseline measurement.
The patient then consumes a standardized meal, a specific component of the test. This meal commonly consists of liquid egg whites or an equivalent food item, like oatmeal, mixed with a small, safe dose of a radioactive isotope, most often Technetium-99m sulfur colloid. The prepared meal, which also includes items like toast and jelly, must be eaten completely and quickly, usually within a ten-minute window, to begin the test at a precise starting time.
Once the meal is ingested, the imaging schedule begins immediately, marking the zero-hour time point. The patient lies under a gamma camera that detects the radiation emitted by the isotope. Subsequent images are acquired at predetermined intervals to track the meal’s movement out of the stomach.
The standard imaging protocol requires images at one, two, and four hours after the meal is finished. The patient must remain quiescent and avoid eating or drinking anything else throughout the four-hour duration to avoid stimulating the stomach muscles or interfering with the measurements. This adherence to a precise schedule and fasting is important for comparing the patient’s data to the established normal range.
Defining Normal Results
Interpreting the results relies on comparing the percentage of the meal retained in the stomach against accepted benchmarks at each time interval. The normal range defines the expected rate at which a healthy stomach should process and empty the standardized solid meal into the small intestine. These established parameters ensure consistency across different testing facilities and provide a clear definition of proper gastric function.
The retention percentage is calculated by measuring the radioactivity remaining in the stomach at a given time point, correcting for the natural decay of the isotope. A healthy stomach shows a progressive decrease in the retained meal over the four-hour period. Normal results indicate that the stomach muscles and nerves are coordinating effectively to move the solid food at an appropriate pace.
At the one-hour mark, a normal result means the stomach retains between 30% and 90% of the original meal. This wide range reflects the initial phase where the stomach is actively mixing and breaking down the solid food. By the two-hour mark, the emptying process should be significantly underway.
A stomach functioning normally should retain 60% or less of the meal two hours after ingestion. This two-hour benchmark is often used as a preliminary indicator of delayed emptying, though the four-hour result is the definitive standard for diagnosis.
The most important measurement for defining a normal study is the final retention percentage at four hours. For a result to be considered normal, the stomach must retain 10% or less of the original radioactive meal. This confirms that the stomach has completed the bulk of its work and moved the solid contents into the lower digestive tract within the expected timeframe.
Interpreting Abnormal Findings
When retention percentages fall outside the normal ranges, it signals a motility disorder, categorized as either delayed or rapid gastric emptying. Delayed gastric emptying is medically termed gastroparesis, often described as a paralyzed stomach. This diagnosis is made when meal retention is greater than 60% at two hours or greater than 10% at four hours.
The delayed movement means food remains in the stomach for too long, leading to symptoms like persistent vomiting, bloating, and feeling full almost immediately after eating. Diabetes is the most frequent underlying cause of gastroparesis, as high blood sugar can damage the vagus nerve that controls stomach muscle function.
Conversely, rapid gastric emptying, known as Dumping Syndrome, occurs when the stomach empties its contents too quickly into the small intestine. A diagnosis of rapid emptying is considered if less than 70% of the meal is retained at 30 minutes, or if less than 30% is retained at the one-hour mark.
This rapid transit causes a sudden, large influx of food into the small intestine, triggering symptoms such as diarrhea, lightheadedness, and a rapid heart rate. Dumping Syndrome is most commonly observed in patients who have undergone previous stomach surgeries, such as gastric bypass or other procedures that alter the stomach’s structure.