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G.I. Bleed


Refer to Policy Nuclear Medicine/Administration 1.45 "RBC and WBC administration procedure"


  • Localization of gastrointestinal bleeding sites.
  • Localization of non‑gastrointestinal bleeding sites.

Contraindications: No barium studies 2 days prior to exam.

Exam time length:

  • Variable depending on whether and when the site of bleeding is identified.
  • The study may be terminated as soon as the site is identified.
  • Imaging can be performed for up to 24 hours with a single injection of radiopharmaceutical. Usually the patient will not tolerate lying under the camera for more than 3 hours at a time. However, imaging may be stopped and restarted.

Patient Preparation: No barium studies 2 days prior to exam.

Radiopharmaceutical & Dose

  • Radiopharmaceutical: Tc‑99m‑red blood cells.
  • Red blood cell labeling method (in vitro method): Use RBC labeling kit (Anazao Health) or Ultratag kit (Mallinckrodt)
  • Dose:
    • Adult: 35 mCi.
    • Pediatric: 0.2 mCi/kg (Dosing Range 1-26 mCi)

Administration Technique: Standard intravenous injection


Time interval between tracer injection and imaging: Scanning begins at time of injection.

Collimator: Large field of view. Low energy, high resolution, parallel hole.

Patient position: Supine. Imaging field: Usually abdomen and pelvis; may exclude uppermost abdomen. (Occasionally position over a different part of the body depending on suspected site of bleed.)

Energy: 20% window centered at 140 keV.

Matrix: 128 x 128

Time /View

  • Initial flow: anterior, 5 seconds per frame for 60 seconds.
  • Acquire serial 60 second images for 60 minutes.

Images taken: Anterior flow. Images in other projections may be acquired if needed, e.g. R LAT or L LAT.

Screen caps to make: Flow – 1hr at 5 minutes/image (16 on 1), Planar Statics (16 on 1).

Send to FUJI: Screen caps, raw data

Send to Dr. PET: None

Additional notes

  • Imaging may be resumed without an additional radiopharmaceutical injection for up to 24 hours.
  • Recommended per Dr. Manske, delayed random views at 6 hours if not after 10:00 pm often are helpful and are strongly suggested. Radiologist needs to write an order for re-imaging any time patient re-bleeds.
  • Radiologist should call report to patient’s physician.
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