Parents often ask if they must wean before having a medical diagnostic scan or x-ray. In most situations, weaning is not necessary. It all depends on what contrast medium is used to make parts of the doy show up when x-rayed or scanned. Contrast media are taken orally or injected and sometimes they are not used.
The first step is to gather information about the type of testing that is being recommended. Ask your healthcare provider for
- the name of the test and if a contrast medium will be used
- the name of the contrast medium. It will be either a radio-contrast compound or radio-opaque contrast media (i.e. the drug used for the x-ray or scan.)
MRI Scan (Magnetic Resonance Imaging)
- An MRI is best for looking at soft tissue (brain, muscle, cancers, blood vessels, etc.). It can also be used for looking at bones.
- It uses a radio-contrast medium that shows body parts with magnetic imaging.
- The contrast substance most commonly used is gadolinium-based contrast agent (GBCA). It is not radioactive. Half of the drug is cleared after 2 hours. It is completely eliminated from the body in 24 hours.
- Less than 0.04% of the dose of gadolinium-based contrast will appear in a mother’s milk and only 0.8% of that is absorbed by the baby.
- Numerous studies have shown that gadolinium-based contrast is safe for the breastfeeding child. The taste of breastmilk may be altered slightly after use, but it is not harmful to the child.
- To enable a detailed examination, mannitol and hyoscine may also be given during MRIs. No levels of these substances have been reported in breastmilk.
- Those with claustrophobia are given conscious sedation.
CT Scan or CAT Scan (Computerized Axial Tomography)
- This scan is the gold standard for looking at bleeding (clots), tumours, inflammation, bone or tissue injury. It is also used for guiding the passage of a needle for surgery or treatment.
- The patient drinks a compound that contains iodine. Multiple x-rays are taken encircling the body. The iodine reveals the bones or tissues.
- The contrast substance used is not radioactive.
- The iodine in the contrast material is bound to a molecule forming the compound. The compound does not enter the milk in any noticeable amount. The compound does not release enough iodine to alter the infant’s thyroid function.
IVP (Intravenous Pyleogram) or lymphangiogram
- This test uses a contrast media similar to the MRI (see above).
- The contrast medium is delivered intravenously (by an IV) to show the kidney, lymph nodes or blood vessels on the x-ray.
Positron Emission Tomography (PET Scan) - a type of nuclear medicine test
- The PET Scan is used in cancer diagnosis.
- It uses the radioactive contrast fludeoxyglucose-F18 (FDG). FDG is not excreted into breastmilk, so milk expressed immediately after the procedure can be given to the baby.
- However, because FDG concentrates in the breast tissue, it is recommended that you not have physical contact with your baby for 12 hours after the administration of FDG.
Other nuclear medicine scans using radioactive agents include: bone scans, some thyroid imaging, renal imaging, cardiac imaging, multigated acquisition scan (MUGA)
- Depending on the type of radioactive agent used in these tests, temporary weaning may be recommended in order to protect your baby from ingestion of the radioactive compound in breastmilk.
- “Decay time” is the total time needed for the medium to leave a person’s body. The term “half-life” refers to both the length of time it takes for ½ of the contrast medium to leave the body and the time it takes for the level of radioactivity to decrease by 50%. Decay time is usually 5-10 half-lives.
- Many radioactive agents, such as many forms of Technetium-99m do not require any interruption in breastfeeding. Very small amounts of these compounds enter the breastmilk. Speak with your healthcare provider about the specific radioactive agent to be used in your situation.
- If the radioactive agent has a long decay time, it will not be safe for your baby to breastfeed. You will have to wait until most of the radioactive agent has left your body. The exact length of time required will depend on the type of radioactive compound used and the dosage given. Information on these radioactive compounds is available online (https://www.e-lactancia.org/), from your doctor, from the laboratory where the test is being done, or from your local La Leche League Leader.
- Temporary weaning may be for a few hours or days.
- In some cases, a mother may have to arrange for a caregiver for the baby during the “decay time”.
- You will need to express your milk during this time to maintain your supply. This milk cannot be given to your baby. It will need to be tossed. Your local La Leche League Leader can provide you with support as you decide how to handle the situation.
- You may wish to hand express or pump and freeze your milk before the procedure. This milk can be fed to your baby after the procedure while the radioactive substance is being cleared from your body.
Radioactive Scans Using Radioactive Iodine (some thyroid imaging)
- A radioactive form of iodine (I) (not to be confused with non-radioactive iodine which is sometimes used for CT scans) unfortunately requires either temporary and sometimes permanent weaning.
- Recommendations with regard to breastfeeding after the use of Iodine-123 vary. Some sources recommend no interruption to breastfeeding. Others recommend up to 3 weeks interruption. Speak with your healthcare provider about your specific situation.
- Milk can be measured for radioactivity before being given to your child.
- Use of Iodine-131 requires complete cessation of breastfeeding. It is recommended that breastfeeding is stopped at least 4 weeks before receiving a therapeutic dose of I-131. This reduces the amount of radiation your breasts are exposed to during the procedure.
Consider other options
If you have been told to wean your baby for one of the first three scans, you may be able to consider other options. Here are some questions to discuss with your healthcare provider:
- Has your healthcare provider said that your baby must be temporarily weaned?
- If yes, why is weaning necessary?
- Have you discussed with your doctor the risks of temporary weaning?
- Can the test be postponed?
- Is another less invasive procedure possible?
If you have any breastfeeding questions or concerns, contact your local La Leche League Canada Leader who can provide you with support and information to share with your healthcare provider.
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Mitchell, K. B., Fleming, M. M, Anderson, P. O., Giesbrandt, J. G. (2019). ABM Clinical Protocol #31: Radiology and Nuclear Medicine Studies in Lactating Women. Breastfeeding Medicine, vol 14. DOI: 10.1089/bfm.2019.29128.kbm
Society of Radiographers. (2022, January 25). SoR joint statement on safety of breastfeeding after contrast agent: Evidence indicates cessation of breastfeeding not required. The Society of Radiographers.