Pregnancy And Contrast Dye: Is It Safe?

The use of imaging methods with or without contrast agent administration in pregnant and breastfeeding women has been increasing in the past decades. However, the use of contrast media is generally avoided by physicians and patients, mainly due to the lack of wide prospective studies on humans and the unknown effects on a human embryo and fetus.

Iodinated and gadolinium-based contrast agents (GBCA) are the most frequently used, as CT and MRI, respectively, are the imaging modalities mainly used in daily practice.

The Food and Drug Administration (FDA) classifies the iodinated contrast agents as pregnancy category B drugs as they are considered safe for pregnant women and lactating mothers, except for diatrizoate meglumine and diatrizoate meglumine sodium, which are classified as category C drugs. The American College of Obstetricians and Gynecologists recommends their use in cases of effective need for additional diagnostic information which could affect maternal or fetal care and outcome.

Gadolinium-based contrast agents are intravenous drugs used to enhance the quality of MRI or magnetic resonance angiography. The FDA classifies GBCA as category C agents: their use in animals showed some adverse effects, but studies in humans are lacking. Their use is recommended when the potential benefits overcome the risks.

The use of gadolinium-based contrast enhancement during pregnancy is controversial. Uncertainty surrounds the risk of possible fetal effects because gadolinium is water-soluble and can cross the placenta into the fetal circulation and amniotic fluid. Free gadolinium is toxic and, therefore, is only administered in a chelated (bound) form. In animal studies, gadolinium agents have been found to be teratogenic at high and repeated doses. In humans, the principal concern with gadolinium-based agents is that the duration of fetal exposure is not known because the contrast present in the amniotic fluid is swallowed by the fetus and reenters the fetal circulation.

The use of gadolinium-based contrast agents for MRI during pregnancy has been assessed by the FDA, who concluded that gadolinium use during pregnancy should be limited and used in accordance with professional society guidelines.

Iodinated contrast agents are considered safe for pregnant women and lactating mothers

Iodinated contrast agents are used in CT scans to improve the detection rate of imaging. They are the most frequently used contrast agents, as CT is the imaging modality most often used in clinical practice. CT employs ionizing electromagnetic radiations (X-rays) to create cross-sectional slice pictures inside selected areas of the body from different angles, creating a three-dimensional picture.

The adverse effects in pregnant women are the same as those of the general population: the most common being hypersensitivity, thyroid dysfunction, and nephropathy. There is no evidence of teratogenic effects in humans, but studies on animals suggest no teratogenic or mutagenic effects if used during pregnancy. The transplacental passage of ionic agents has been demonstrated by experimental studies on animals. However, there is no clear evidence of the transplacental passage of nonionic agents.

The European Society of Urogenital Radiology recommended that neonatal thyroid function should be checked during the first week after birth if iodinated contrast media was given during pregnancy.

The safety of iodinated contrast agents is widely evident. Nevertheless, the lack of clinical studies on humans favours the doubts about their use in pregnant women, as this has been described only in a few case reports.

As far as concerns breastfeeding, the iodinated contrast agents are completely cleared from the mother's bloodstream within 24 hours and their half-life in the blood is 2 hours. Less than 1% of the administered iodine agent is excreted in milk and less than 1% of it is assumed by the breastfed baby. Consequently, the median dose absorbed by the baby is 0.05% of the recommended safe dose to administer if the infant needs a diagnostic imaging examination.

In conclusion, mothers can safely breastfeed their babies after exposure to iodine contrast agents; they can, however, stop breastfeeding for 12-24 hours if they are still concerned.

Gadolinium-based contrast agents are safe for pregnant women but should be used only when the benefits outweigh the risks

Gadolinium-based contrast agents are used to enhance the quality of MRI or magnetic resonance angiography. They are considered safe for pregnant women and are categorised as "Pregnancy category B drugs" by the Food and Drug Administration (FDA). However, they should be used only when the benefits outweigh the risks.

Gadolinium-based contrast agents are generally avoided by physicians and patients due to the lack of wide prospective studies on humans and the unknown effects on a human embryo and fetus. However, they are considered safe for pregnant women and lactating mothers by the FDA, except for diatrizoate meglumine and diatrizoate meglumine sodium, which are classified as category C drugs.

Gadolinium-based contrast agents are assumed to cross the placenta and enter the fetal circulation and amniotic fluid. Gadolinium is toxic in its free form, so it is administered in a chelated (bound) form. Gadolinium exposure during early pregnancy has been reported in a small number of cases without apparent adverse effects. However, gadolinium agents have been found to be teratogenic at high and repeated doses in animal studies.

The American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG) recommend that gadolinium-based contrast agents should be limited and used only when the benefits clearly outweigh the possible risks. They should be used in pregnant women only if they significantly improve diagnostic performance and are expected to improve fetal or maternal outcomes.

The use of gadolinium-based contrast agents during pregnancy is a decision that should be made by the clinician and the patient together, taking into account the potential benefits and risks.

Fluorodeoxyglucose is a category C agent and should be given to a pregnant woman only if clearly indicated

Fluorodeoxyglucose (FDG) is a radiopharmaceutical agent used in positron emission tomography (PET) scans. It is a radioactive tracer that acts as a glucose analog, taken up by high-glucose-using cells such as those in the brain, kidneys, and tumours.

FDG is categorised as a 'Category C' agent by the Food and Drug Administration (FDA). This means that animal reproduction studies have not been conducted with FDG injections, and it is not known whether it can cause harm to the foetus when administered to a pregnant woman or affect her reproductive capacity.

Therefore, FDG injections should only be given to a pregnant woman if clearly indicated. The potential benefits of the procedure must outweigh the potential risks. This is a decision that should be made by the patient and their doctor together.

If a PET scan is deemed necessary, the patient should have an empty bladder during the procedure, and a longer imaging time should be used to reduce the foetal absorbed dose. It is also important to ensure the patient is normoglycaemic when undergoing PET imaging with FDG injections.

There is very little information available about the safety of PET scans in pregnancy. However, FDG seems to be relatively safe when administered to adults, and no adverse drug reactions linked to FDG injections have been reported that required medical intervention.

Barium sulfate is contraindicated if bowel perforation is suspected

Barium sulfate is a contrast medium used for radiographic examinations of the gastrointestinal mucosa. It is a radiopaque substance, meaning it cannot be penetrated by x-rays. Barium sulfate is insoluble and non-toxic, and is not absorbed by the gastrointestinal tract, remaining in the lumen.

If perforation is suspected, an iodinated water-soluble contrast medium is recommended instead.

Gastrographin is a water-soluble contrast media used as an alternative to barium sulfate

Gastrographin, also known as Gastrografin, is a water-soluble contrast media formed by diatrizoate meglumine and diatrizoate sodium. It is used as an alternative to barium sulfate in patients who are at higher risk for bowel obstruction or perforation.

Gastrografin is administered orally or as a solution enema, and it is safe for both oral and rectal administration in infants. It is also safe for pregnant women, although there is limited evidence on its use during pregnancy. In a study involving 15 red-eared slider turtles, Gastrografin was found to be easier to administer than barium sulfate, with a faster transit time and only minor haematological changes. However, the visualisation of Gastrografin in the lower gastrointestinal tract was insufficient for an accurate diagnosis.

Gastrografin has a faster transit time than barium sulfate, and it does not carry the risk of regurgitation. It is a good choice when gastrointestinal perforation is suspected, but it should not be administered to dehydrated patients because of its hyperosmolar properties.

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