Gastric Emptying Study Test

A gastric emptying study test is one test that is used to help make the diagnosis of gastroparesis where the stomach empties too slowly, or dumping syndrome, where the stomach empties too quickly.

The gastric emptying study test, also known as gastric emptying scintigraphy (scintillation=flashes of light + graphy=picture) is a nuclear medicine test used to measure the rate at which the stomach digests food and then empties into the intestine.

It is one test that is used to help make the diagnosis of gastroparesis where the stomach empties too slowly, or dumping syndrome, where the stomach empties too quickly.

A standardized meal of scrambled eggs, toast, and water is eaten by the patient. The food contains a radioactive isotope that emits gamma radiation that can be detected by a camera held outside the body. This produces a “picture” of where the food is in the stomach, and with repeated images over time can measure how much food has exited the stomach. The radiation involved is minimal and not harmful to adults.

This test is not recommended in pregnancy and could potentially be damaging to a rapidly growing fetus.

The stomach is a muscular mixing bowl that takes food that is eaten and begins the process of digestion.

When we eat, food passes from the mouth through the esophagus and into the stomach. The muscles of the stomach wall relax and allow it to distend and make room for the food. Digestive juices and enzymes are mixed in and the food churns to be broken into tiny bits that can then be passed into the duodenum, the first part of the small intestine, where further digestion occurs.

A healthcare provider may order the gastric emptying study to help make the diagnosis in patients who have upper abdominal discomfort, and other symptoms that may include bloating, belching, nausea and vomiting, reflux, early satiety (the feeling of being full), or prolonged fullness.

The test can diagnose two main abnormalities:

• Gastroparesis (gastro=stomach + paresis=weakness) where the stomach emptying is delayed.
  • Causes may include:
    • Diabetes is the most common cause in almost a third of patients with gastroparesis
    • Side effect of some medications like opioids and antidepressants
    • In association with other gastrointestinal diseases like Crohn’s disease, ulcerative colitis, celiac disease, or GERD (gastroesophageal reflux disease)
    • Thyroid or adrenal disease
    • Virus infections
    • Complications of stomach surgery
  • Unfortunately, in about half of patients, the cause is not found
• Dumping syndrome describes the situation where food, especially those high in sugar, leave the stomach too quickly.
  • Dumping causes symptoms like abdominal cramping, rapid heart rate, lightheadedness, flushing, sweating, and nausea and vomiting
  • It can occur immediately after eating or can be delayed by 1-3 hours
  • Dumping syndrome most often occurs after stomach or esophagus surgery. Its onset can be delayed by years

Can a gastric emptying study show cancer?

The gastric emptying study is just one test that can help in diagnosing stomach disorders. It is not meant to diagnose cancers.

Some cancers, like those of the lung or pancreas may be associated with gastroparesis.

Often, before a gastric emptying study is ordered, other tests are often done. A CT or MRI scan of the abdomen may be performed to look for causes of abdominal pain. An upper GI endoscopy may be considered to look for structural abnormalities and obstruction of the esophagus, stomach, and duodenum.

What to expect from a gastric emptying study

You will first be asked to eat the meal containing the radioactive tracer quickly, within 10 minutes.

The nuclear medicine technician will take repeated pictures of the area of the stomach with you standing and lying flat.

The pictures will be taken immediately, and then again at 30 minutes, one hour, two hours, and four hours.

You will be able to the leave the area and walk around in between image sessions if you choose.

If there is concern for dumping syndrome, a liquid meal may be used in place of a solid meal. Liquid meals are not helpful in gastroparesis diagnosis because liquids may pass normally from the stomach into the duodenum, even though solid foods may not.

How long does a gastric emptying study take?

The test takes four hours. The test may end after two hours if the stomach is found to be empty at that time.

What do you eat for a gastric emptying study?

You should have nothing to eat or drink for 4 hours before the test begins.

The meal for the test usually consists of two scrambled eggs, toast, fruit jam, and water.

What medications should you avoid before a gastric emptying study?

Patients with diabetes may have to adjust their dosage due to the fasting requirement before the test and the content of the meal. Patients should bring their glucose meter and their insulin to the appointment; in case their blood sugar falls too low or increases too high.

Some medications may affect the emptying rate of the stomach and should not be taken. A few examples include:

• Opioids
• Antidepressants
• Calcium channel blockers
• Antacid medications
• Anticoagulants (blood thinners)

Your healthcare provider needs to know all the patient’s medications and will advise which ones need to be taken, which ones to stop, and when to stop them before the test.

The results of the gastric emptying study will help decide whether gastroparesis or dumping syndrome is present. These are often caused by an underlying disease. In addition to treating the symptoms, the healthcare provider will try to determine the cause of the abnormal stomach function.

Normal vs. abnormal gastric emptying study results

Normal stomach emptying results:

• at 30 minutes - at least 70% of the meal content remains in the stomach
• at 1 hour - at least 30% is still in the stomach; at least 10% has emptied
• at 2 hours - at least 40% of the meal has emptied
• at 4 hours - at least 90% of the meal has emptied

Abnormal stomach emptying results:

• Gastroparesis
  • at 2 hours - more than 60% of the meal remains in the stomach
  • at 4 hours – more than 10% of the meal remains in the stomach. This may be the most sensitive timeframe to make the diagnosis
• Dumping syndrome
  • at 30 minutes - more than 30% of the meal has emptied from the stomach
  • at 1 hour - more than 70% of the meal has emptied.
  • the patient will also be monitored for symptoms like rapid heart rate and change in blood sugar levels throughout the test duration.

There are no side effects from a gastric emptying study.

The radioactive material is not absorbed into the body and is eliminated in the stool.

The test should not be performed in pregnant women because the rapidly growing fetus would be exposed to radioactivity. Women younger than 50 are usually screened for pregnancy before the study begins.