Medical imaging in pregnancy

Medical imaging in pregnancy
When you are pregnant, new health considerations arise that you usually wouldn’t think about. For example, you might wonder about the safety of diagnostic tests that use radiation. Most medical imaging tests have little to no risk during pregnancy. Understanding any potential health implications will help you make the best choice for you and your baby.

Medical imaging in pregnancy may be indicated because of pregnancy complications, intercurrent diseases or routine prenatal care. 
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Options for medical imaging in pregnancy include the following:

 Magnetic resonance imaging (MRI) without MRI contrast agents as well as obstetric ultrasonography are not associated with any risk for the mother or the fetus, and are the imaging techniques of choice for pregnant women.[1]
    Projectional radiography, X-ray computed tomography and nuclear medicine result some degree of ionizing radiation exposure, but have with a few exceptions much lower radiation doses than what are associated with fetal harm.[1] They are indicated when ultrasonography or MRI are not readily available or not feasible for the diagnostic question at hand.[1]

 Radiocontrast agents, when orally administered, are harmless.[1] Intravenous administration of iodinated radiocontrast agents can cross the placenta and enter the fetal circulation, but animal studies have reported no teratogenic or mutagenic effects from its use. There have been theoretical concerns about potential harm of free iodide on the fetal thyroid gland,[1] but multiple studies have shown that a single dose of intravenously administered iodinated contrast medium to a pregnant mother has no effect on neonatal thyroid function.[2] Nevertheless, it generally is recommended that radiocontrast only be used if absolutely required to obtain additional diagnostic information that will improve the care of the fetus or mother
Magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI), without MRI contrast agents, is not associated with any risk for the mother or the fetus, and together with medical ultrasonography it is the technique of choice for medical imaging in pregnancy.[1]
Safety

For the first trimester, no known literature has documented specific adverse effects in human embryos or fetuses exposed to non-contrast MRI during the first trimester.[3] During the second and third trimesters, there is some evidence to support the absence of risk, including a retrospective study of 1737 prenatally exposed children, showing no significant difference in hearing, motor skills or functional measures after a mean follow-up time of 2 years.[3]

Gadolinium contrast agents in the first trimester is associated with a slightly increased risk of a childhood diagnosis of several forms of rheumatism, inflammatory disorders, or infiltrative skin conditions, according to a retrospective study including 397 infants prenatally exposed to gadolinium contrast.[3] In the second and third trimester, gadolinium contrast is associated with a slightly increased risk of stillbirth or neonatal death, by the same study.[3] Hence, is recommended that gadolinium contrast in MRI should be limited, and should only be used when it significantly improves diagnostic performance and is expected to improve fetal or maternal outcome
Common uses

MRI is commonly used in pregnant women with acute abdominal pain and/or pelvic pain, or in suspected neurological disorders, placental diseases, tumors, infections, and/or cardiovascular diseases.[3] Appropriate use criteria by the American College of Radiology give a rating of ≥7 (usually appropriate) for non-contrast MRI for the following conditions:

    Acute non-localized pain in the right upper quadrant or right lower quadrant (in concurrent fever and leukocytosis)[3]
    Acute pelvic pain when a non-gynecological cause is suspected[3]
    Suspected biliary disease such as jaundice[3]
    Suspected pancreatic disease[3]
    New‐onset severe headache[3]
    Newly diagnosed cance