Can a pregnant woman with sickle cell disease (SCD) receive intravenous (IV) contrast with a computed tomography (CT) scan?

Can Pregnant Women with Sickle Cell Disease Receive IV Contrast with CT Scan?

Yes, pregnant women with sickle cell disease can receive IV contrast with CT scanning when clinically indicated, as the benefits of accurate diagnosis typically outweigh the minimal risks to both mother and fetus.

Safety of IV Contrast in Pregnancy

The primary concern with CT imaging in pregnancy relates to radiation exposure to the fetus, not the iodinated IV contrast itself. The evidence demonstrates:

• Iodinated IV contrast is safer than gadolinium-based MRI contrast during pregnancy, as gadolinium crosses the placenta and has been associated with increased risk of stillbirth, neonatal death, and rheumatologic conditions in offspring 1
• Modern non-ionic iodinated contrast has minimal theoretical risk of neonatal hypothyroidism, though this risk is negligible with current agents 1
• Less than 0.01% of CT contrast appears in breast milk, making breastfeeding safe after administration 1

Radiation Safety Considerations

The radiation exposure from CT imaging poses minimal fetal risk when the scan does not directly involve the abdomen or pelvis:

• Fetal doses below 50 mGy are not associated with detectable increases in adverse fetal outcomes, including malformations, growth restriction, or fetal death 1, 2
• Head CT delivers approximately 2 mGy to the mother and negligible radiation to the fetus 1
• Chest CT delivers less than 0.3 mGy to the fetus 1, 3
• The threshold for significant risk of fetal damage is 100 mGy, well above diagnostic CT doses 1, 2

Clinical Decision-Making Algorithm

When CT with IV contrast is clinically indicated:

1. Document the clinical indication and risk-benefit assessment in the medical record 1
2. Confirm gestational age before proceeding 1
3. Use standard imaging protocols with appropriate radiation safety measures rather than deferring clinically necessary imaging 1
4. Prioritize maternal benefit of accurate diagnosis over theoretical fetal concerns, as fetal radiation exposure from non-abdominal/pelvic CT is negligible 1

Special Considerations for Sickle Cell Disease

Pregnant women with sickle cell disease face increased risks that may necessitate CT imaging with contrast:

• Increased frequency of vaso-occlusive crises and acute chest syndrome during pregnancy 4, 5
• Higher risk of thromboembolism requiring diagnostic imaging 6, 5
• Increased maternal mortality (1-2%) and obstetric complications 4, 5

For suspected pulmonary embolism specifically (a common concern in SCD pregnancy), the American Thoracic Society recommends beginning with chest X-ray, then proceeding to CT pulmonary angiography (CTPA) if needed, as the fetal dose remains well below safety thresholds 3.

Common Pitfalls to Avoid

• Do not withhold clinically indicated CT with IV contrast due to pregnancy alone, as diagnostic delays may pose greater maternal risk than the minimal fetal radiation exposure 1
• Do not substitute gadolinium-enhanced MRI for iodinated contrast CT, as gadolinium carries greater fetal risks 1
• Do not rely on D-dimer testing to exclude pulmonary embolism in pregnant patients with SCD, particularly in the third trimester 3

Imaging Hierarchy in Pregnancy

When diagnostic imaging is needed, follow this general approach:

1. Ultrasound without contrast as first-line 1
2. MRI without gadolinium as second-line when ultrasound is inadequate 1
3. CT with or without IV contrast when diagnosis cannot be made with ultrasound or MRI and the information is essential for maternal or fetal care 1

The key principle: proceed with CT and IV contrast when clinically necessary, as the maternal benefit of accurate diagnosis far outweighs the negligible fetal risk from both radiation and iodinated contrast 1.