A gastric emptying scan, also known as a gastric emptying scintigraphy, may be ordered for both adult and pediatric patients to assess gastric motility disorders and for patients with unexplained nausea, vomiting, diarrhea, and abdominal cramping. The emptying of food by the stomach is a complex process that is controlled by food composition (fats, carbohydrates), food form (liquid, solid), hormone secretion (gastrin, CCK), and innervation. Because clearance of liquids and clearance of solids vary, the gamma camera traces both food forms.

Indications for this scan include both mechanical and nonmechanical gastric motility disorders. Mechanical disorders include peptic ulcerations, gastric surgery, trauma, and cancer. Nonmechanical disorders include diabetes, uremia, anorexia nervosa, certain drugs (opiates), and neurologic disorders. Gastric emptying scan may be done as a solid study, liquid study, or a dual liquid/solid study. The test should be performed in the morning when the rate of gastric emptying is increased.

Dual-Isotope Liquid/Solid Study

1. Ensure that the patient has fasted for at least 6 hours prior to the test and abstained from smoking in the morning of the test, as it slows gastric emptying of solids. Have the patient consume the liquid phase (¹¹¹In-DTPA in 300 mL of water) quickly using a straw.

2. Perform imaging immediately. Advise the patient that this phase takes approximately 30 minutes to complete.

3. Once the liquid phase is complete, have the patient begin the solid phase by consuming scrambled egg whites or egg substitute containing ^99mTc-SC with toasted white bread with jelly in less than 10 minutes. Have infants drink ^99mTc-SC mixed with milk. Provide older children solids such as scrambled eggs mixed with ^99mTc-SC.

4. Perform imaging immediately, with the patient in the upright position, if possible.

5. Obtain subsequent images at hourly intervals of 1, 2, and 4 hours, using the same camera for all images.

6. Use computer processing to determine the half-time clearance for both liquid and solid phases of gastric emptying. Note: Dual-isotope liquid/solid scan may also be performed simultaneously, instead of sequentially because ¹¹¹In-DTPA does not interfere with results of the solid meal.

7. See Chapter 1 guidelines for safe, effective, informed intratest care.

1. Slow or delayed emptying is usually seen in the following conditions:

   1. Peptic ulceration

   2. Diabetes

   3. Smooth muscle disorders

   4. After radiation therapy

   5. For pediatric patients, hypomotility of the antrum portion of the stomach is the primary cause of delayed gastric emptying. However, all abnormal functions of the stomach do contribute to the delay

2. Accelerated emptying is often seen in the following conditions:

   1. Zollinger-Ellison syndrome (triad of peptic ulceration, pancreatic non–beta cell islet tumors, and hypersecretion of gastric acid)

   2. Certain malabsorption syndromes

   3. After gastric or duodenal surgery

Pretest Patient Care

1. Explain the purpose, procedure, benefits, and risks of the study.

2. Have the adult patient fast for 6–8 hours before the test.

3. Refer to standard NMI pretest precautions.

4. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Administration of certain medications (e.g., gastrin, cyholecystokinin) interferes with gastric emptying.

Normal

Normal half-time clearance ranges:

45–110 minutes for solids

10–65 minutes for liquids