Gastric Emptying Scan

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Gastric Emptying Scan

 

Definition

A gastric emptying scan (GES) is an x-ray exam using special radioactive material that allows physicians to identify abnormalities related to emptying of the stomach. Diseases that involve changes in the way the stomach contracts (motility disorders) are best diagnosed by this test.

Purpose

The study is used most frequently to evaluate patients who have symptoms suggestive of decreased, delayed, or rapid gastric emptying, and no visible abnormality to explain their symptoms.
Symptoms pointing to a delay in gastric emptying are non-specific, and may be due to a number of causes, such as ulcers, diabetes, tumors, and others. These symptoms include nausea, upper abdominal bloating, and at times vomiting. Another significant symptom is called "early satiety," which means feeling full after eating only a small amount of food. In some patients, weight loss is also present. In addition to symptoms, the finding of a large amount of material in the stomach after an overnight fast suggests abnormal emptying, but does not distinguish between an actual blockage or an irregularity in gastric contractions. It is therefore essential to find out what is causing material to remain in the stomach.
Since many diseases can produce the above symptoms, structural lesions (such as tumors or regions of narrowing or scar tissue) need to be ruled out first. This is usually done by upper gastrointestinal series test or by endoscopy (examination of the inside of an organ, in this instance the stomach, with an instrument that has a light at the end of it and an optical system for examination of the organ). Once it is clear that a mechanical or physical lesion is not the cause of symptoms, attempts to document an abnormality in the nervous or muscular function of the stomach is then begun. GES is usually the first step in that evaluation.

Precautions

The exam should not be performed on pregnant women, but is otherwise quite safe. Since eggs are usually used to hold the radioactive material, patients should notify their physician if they are allergic to eggs. However, other materials can be used in place of an egg.

Description

Gastric emptying scans have undergone several changes since the initial studies in the late 1970s. During the study, patients are asked to ingest an egg sandwich containing a radioactive substance (for example, technetium) that can be followed by a special camera. The emptying of the material from the stomach is then followed and displayed both in the form of an image, as well as the percentage emptied over several hours (generally two and four hours). Studies are in progress using substances that are not radioactive, but this procedure is not available to the patient as of yet.

Preparation

The only preparation involved is for the patient to fast overnight before the test.

Risks

The radiation exposure during the study is quite small and safe, unless the patient is pregnant.

Normal results

There are several different measurements considered normal, depending on the radioactive material and solid meal used. The value is expressed as a percentage of emptying over a period of time. For a technetium-filled egg sandwich, normal emptying is 78 minutes for half the material to leave the stomach, with a variation of 11 minutes either way.

Abnormal results

GES scan studies that show emptying of the stomach in a longer than accepted period is abnormal. Severity of test results and symptoms do not always match; therefore, the physician must carefully interpret these findings. Diabetic injury to the nerves that supply the stomach (called diabetic gastroparesis) is one of the most common causes of abnormal gastric motility. However, up to 30% of patients have no obvious cause to explain the abnormal results and symptoms. These cases are called idiopathic (of unknown cause). GES is often used to follow the effect of medications used for treatment of motility disorders.

Resources

Organizations

American Pseudo-Obstruction and Hirschprung's Disease Society. 158 Pleasant St., North Andover, MA 01845-2797. http://www.tiac.net/users/aphs.

Key terms

Endoscopy — The examination of the inside of an organ with an instrument that has a light at the end of it and an optical system for examination of the organ.
Motility — Motility is spontaneous movement. One example is the automatic stomach contractions that move the food content along from the stomach into the intestines. A motility disease is one that involves changes in the way the stomach contracts.

Gastric Emptying Scan

Synonym/acronym: Gastric emptying quantitation, gastric emptying scintigraphy.

Common use

To visualize and assess the time frame for gastric emptying to assist in the diagnosis of diseases such as gastroenteritis and dumping syndrome.

Area of application

Esophagus, stomach, small bowel.

Contrast

Oral radioactive technetium-99m sulfur colloid.

Description

A gastric emptying scan quantifies gastric emptying physiology. The procedure is indicated for patients with gastric motility symptoms, including diabetic gastroparesis, anorexia nervosa, gastric outlet obstruction syndromes, postvagotomy and postgastrectomy syndromes, and assessment of medical and surgical treatments for diseases known to affect gastric motility. A radionuclide is administered, and the clearance of solids and liquids may be evaluated. The images are recorded electronically, showing the gastric emptying function over time.

This procedure is contraindicated for

  • Patients who are pregnant or suspected of being pregnant, unless the potential benefits of a procedure using radiation far outweigh the risks to the fetus and mother.
  • Patients with esophageal motor disorders or swallowing difficulties.

Indications

  • Investigate the cause of rapid or slow rate of gastric emptying
  • Measure gastric emptying rate

Potential diagnosis

Normal findings

  • Mean time emptying of liquid phase: 30 min (range, 11 to 49 min)
  • Mean time emptying of solid phase: 40 min (range, 28 to 80 min)
  • No delay in gastric emptying rate

Abnormal findings related to

  • Decreased rate:
    • Dumping syndrome
    • Duodenal ulcer
    • Malabsorption syndromes
    • Zollinger-Ellison syndrome
  • Increased rate:
    • Amyloidosis
    • Anorexia nervosa
    • Diabetes
    • Gastric outlet obstruction
    • Gastric ulcer
    • Gastroenteritis
    • Gastroesophageal reflux
    • Hypokalemia, hypomagnesemia
    • Post–gastric surgery period
    • Postoperative ileus
    • Post–radiation therapy period
    • Scleroderma

Critical findings

    N/A

Interfering factors

  • Factors that may impair clear imaging

    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status.
    • Metallic objects (e.g., jewelry, body rings) within the examination field, which may inhibit organ visualization and cause unclear images.
    • Retained barium from a previous radiological procedure.
    • Other nuclear scans done within the previous 24 to 48 hr.
    • Administration of certain medications (e.g., gastrin, cholecystokinin), which may interfere with gastric emptying.
  • Other considerations

    • Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.
    • Consultation with a health-care provider (HCP) should occur before the procedure for radiation safety concerns regarding younger patients or patients who are lactating. Pediatric & Geriatric Imaging Children and geriatric patients are at risk for receiving a higher radiation dose than necessary if settings are not adjusted for their small size. Pediatric Imaging Information on the Image Gently Campaign can be found at the Alliance for Radiation Safety in Pediatric Imaging (www.pedrad.org/associations/5364/ig/).
    • Risks associated with radiation overexposure can result from frequent x-ray or radionuclide procedures. Personnel working in the examination area should wear badges to record their level of radiation.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in evaluating the time it takes for the stomach to empty.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to eggs, latex, anesthetics, sedatives, or radionuclides.
  • Obtain a history of the patient’s gastrointestinal system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results, including examinations using barium- or iodine-based contrast medium.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that some pain may be experienced during the test, and there may be moments of discomfort. Reassure the patient that the radionuclide poses no radioactive hazard and rarely produces side effects. Inform the patient that the procedure is performed in a nuclear medicine department by an HCP specializing in this procedure, with support staff, and takes approximately 30 to 120 min. Pediatric Considerations Preparing children for a gastric emptying scan depends on the age of the child. Encourage parents to be truthful about what the child may experience during the procedure (e.g., length of time the exam will take and the need to intermittently have scans performed), stressing the importance of eating as much of the “breakfast” as possible so the test is successful, and to use words that they know their child will understand. Toddlers and preschool-age children have a very short attention span, so the best time to talk about the test is right before the procedure. The child should be assured that he or she will be allowed to bring a favorite comfort item into the examination room, and if appropriate, that a parent will be with the child during the procedure. Explain the importance of remaining still while the images are taken.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during and after the procedure.
  • Instruct the patient to restrict food and fluids for 8 hr before the scan. Inquire about allergic reactions to eggs. Protocols may vary among facilities.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.

Intratest

  • Potential complications:
  • Although it is rare, there is the possibility of allergic reaction to the radionuclide. Have emergency equipment and medications readily available. If the patient has a history of allergic reactions to any substance or drug, administer ordered prophylactic steroids or antihistamines before the procedure.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure the patient has complied with dietary and fluid restrictions for 8 hr before the scan. Ensure that the patient does not have a known allergy to eggs.
  • Ensure that the patient has removed all external metallic objects from the area to be examined prior to the procedure.
  • Instruct the patient to void prior to the procedure and to change into the gown, robe, and foot coverings provided.
  • Record baseline vital signs and neurological status. Protocols may vary among facilities.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Instruct the patient to lie still during the procedure because movement produces unclear images.
  • Administer sedative to a child or to an uncooperative adult, as ordered.
  • Place the patient in an upright position in front of the gamma camera.
  • Ask the patient to take the radionuclide mixed with water or other liquid orally, or combined with eggs for a solid study. Pediatric Considerations If the patient is an infant, a small amount of radionuclide will be added to the patient’s feeding.
  • Images are recorded over a period of time (30 to 60 min) and evaluated with regard to the amount of time the stomach takes to empty its contents.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Advise the patient to drink increased amounts of fluids for 24 to 48 hr to eliminate the radionuclide from the body, unless contraindicated. Tell the patient that radionuclide is eliminated from the body within 6 to 24 hr.
  • Monitor vital signs every 15 min for 1 hr, then every 2 hr for 4 hr, and then as ordered by the HCP. Monitor intake and output at least every 8 hr. Compare with baseline values. Protocols may vary among facilities.
  • Instruct the patient to resume usual diet, fluids, medication, and activity, as directed by the HCP.
  • If a woman who is breastfeeding must have a nuclear scan, she should not breastfeed the infant until the radionuclide has been eliminated. This could take as long as 3 days. She should be instructed to express the milk and discard it during the 3-day period to prevent cessation of milk production.
  • Instruct the patient to immediately flush the toilet and to meticulously wash hands with soap and water after each voiding for 24 hr after the procedure.
  • Instruct all caregivers to wear gloves when discarding urine for 24 hr after the procedure. Wash gloved hands with soap and water before removing gloves. Then wash hands after removing the gloves.
  • Recognize anxiety related to test results, and be supportive of perceived loss of independent function. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be needed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include barium swallow, biopsy kidney, biopsy liver, biopsy lung, calcitonin stimulation, calcium, capsule endoscopy, CT abdomen, esophageal manometry, EGD, fecal analysis, gastric fluid analysis and gastric acid stimulation test, gastrin and gastrin stimulation test, GI blood loss scan, glucose, glycated hemoglobin, H. pylori antibodies, liver and spleen scan, magnesium, PTH, UGI and small bowel series, and vitamin B12.
  • Refer to the Gastrointestinal System table at the end of the book for related tests by body system.