From the Guidelines
Contraindications for a Nuclear Medicine (NM) bleed scan include pregnancy, breastfeeding, and hypersensitivity to the radiopharmaceuticals used. The primary concern with NM bleed scans is the potential for radiation exposure, particularly in pregnant women, where the risk to the fetus must be considered 1. Breastfeeding mothers should also be cautious, as they may need to temporarily discontinue nursing for a period after the scan. Other considerations include:
- Recent administration of certain medications, such as heparin or dextran, which can interfere with red blood cell labeling
- Severe anemia, which may limit the ability to withdraw sufficient blood for labeling
- Inability to remain still during imaging, which can compromise image quality
- Patients who have received blood transfusions within 24-48 hours, as the presence of donor cells may lead to unreliable results These factors can affect the diagnostic accuracy of the NM bleed scan or pose unnecessary risks to the patient, and should be carefully evaluated before proceeding with the procedure 1. It is essential to weigh the potential benefits of the NM bleed scan against these contraindications, considering the patient's overall health status and the severity of their condition, to ensure the best possible outcome in terms of morbidity, mortality, and quality of life.
From the Research
Contraindications for NM Bleed Scan
- Pregnancy is a significant contraindication for a Nuclear Medicine (NM) bleed scan, as some radiopharmaceuticals used in the procedure can pose significant fetal risks 2, 3, 4.
- The use of certain radiopharmaceuticals, such as those containing high levels of free radioiodine (e.g., 131I- and 123I-iodide), is contraindicated in pregnant women due to the high doses delivered to the fetal thyroid 3.
- Breastfeeding is also a consideration, as many radiopharmaceuticals are excreted through breast milk, and breastfeeding interruption recommendations should be followed to keep the effective dose to the infant below 1 mSv 3.
- The Society of Nuclear Medicine recommends pregnancy testing before any procedure that will expose the fetus to >50 mGy, and the dose of radionuclide to be employed should be kept as low as possible without sacrificing radiographic information 4.
- However, in life-threatening situations, such as colorectal bleeding, the benefits of the NM bleed scan may outweigh the risks, and the procedure can be performed with careful planning and consideration of the potential risks to the fetus 5, 6.