Type of test  : Nuclear scan

Normal findings

 No collection of radionuclide in GI tract Test explanation and related physiology The GI bleeding scan is a test used to localize the site of bleeding in patients who are having active GI hemorrhage. The scan also can be used in patients who have suspected intraabdominal hemorrhage from an unknown source.

 Arteriography has limitations in its evaluation of GI bleeding. Arteriography can determine the site of bleeding only if the rate of bleeding exceeds 0.5 mL/min for detection. The GI bleeding scan has several advantages over arteriography. It can detect bleeding if the rate is greater than 0.05 mL/min. Also, with the use of 99mTc-labeled red blood cells (RBCs), delayed films (as long as 24 hours) can be obtained, indicating the site of an intermittent or extremely slow intestinal bleed.

 A GI scintigram is sensitive in locating the area of GI bleeding; however, it is not very specific in pinpointing the site or cause of bleeding. It is important to realize that this test can take 1 to 4 hours to obtain useful information. An unstable patient may need to go to surgery in minutes.

Contraindications

 • Patients who are pregnant or lactating, unless the benefits outweigh the risks

 • Medically unstable patients

Interfering factors

• Barium in the GI tract may mask a small source of bleeding.

Procedure and patient care

Before

* Explain the procedure to the patient. See p. xviii for radiation exposure and risks.

* Inform the patient that no pretest preparation is required.

* Assure the patient that only a small amount of nuclear material will be administered.

* Instruct the patient to notify the nuclear medicine technologist if he or she has a bowel movement during the test. Blood in the GI tract can act as a cathartic.

During

 • Note the following procedural steps:

 1. Ten millicuries of freshly prepared 99mTc-labeled sulfur colloid is administered intravenously to the patient. If 99mTc labeled RBCs are to be used, 3 to 5 mL of the patient’s own blood is combined with the 99mTc and reinjected into the patient.

2. Immediately after administration of the radionuclide, the patient is placed under a scintillation camera.

3. Multiple images of the abdomen are obtained at short intervals (5-15 minutes).

4. Detection of radionuclide in the abdomen indicates the site of bleeding. If no bleeding sites are noted in the first hour, the scan may be repeated at hourly intervals for as long as 24 hours.

• Note that areas of the bowel hidden by the liver or spleen may not be adequately evaluated by this procedure. Also, the rec tum cannot be easily evaluated because other pelvic structures (e.g., the bladder) obstruct the view.

• Note that this test is usually performed in approximately 60 minutes by a technologist in nuclear medicine.

* Tell the patient that the only discomfort associated with this study is the injection of the radioisotope.

After

* Assure the patient that only tracer doses of radioisotopes have been used and that radiation precautions are not necessary.

Abnormal findings

- Ulcer

- Tumor

- Angiodysplasia

- Polyps

- Diverticulosis

- Inflammatory bowel disease

- Aortoduodenal fistula