What is the risk of adverse effects on the fetus due to maternal Computed Tomography (CT) scan?

From the Guidelines

CT scans during pregnancy pose minimal risk to the fetus when medically necessary, with the estimated increase of cancer incidence following fetal exposure to 50 mGy being 1.1 to 3 by 1000, which is considered minimal 1. The primary concern with CT scans in pregnant women is the potential increased cancer risk to the fetus, which is theoretically possible at any dose due to the stochastic effect of radiation on fetal DNA 1. However, the radiation dose from a typical CT scan, especially when techniques to minimize exposure are employed, remains well below the thresholds associated with fetal damage. Key points to consider include:

• The risk of developing cancer subsequent to application of an imagery technique is minimal, with an overall risk of death by cancer during childhood being extremely low (1 to 2.5 by 1000) 1.
• Ultrasound and magnetic resonance imaging are the usual imaging techniques recommended for pregnant women, but if thoracic, abdominal, and pelvic computed tomography (TAP CT) is necessary, it should not be avoided due to pregnancy 1.
• Any healthcare professional managing a pregnant woman requiring imagery for diagnostic purposes must consider the risk-benefit balance of exposure to radiological procedures, and at birth, any use of imagery using a contrast agent must be mentioned to the pediatrician 1. When a CT scan is medically indicated, the benefit to the mother typically outweighs the small risk to the fetus, and techniques to minimize radiation exposure, such as shielding the abdomen and pelvis when imaging other body parts and using the lowest dose necessary for diagnosis, should be employed.

From the Research

Risk of Adverse Effects on Fetus due to Maternal CT Scan

• The risk of adverse effects on the fetus due to maternal CT scan is a concern, as fetuses are more sensitive to radiation and the effects of medical imaging compared to adults 2.
• Fetal risks of medical imaging include slow growth and development of the fetus, abortion, malformations, impaired brain function, abnormal childhood growth, and neurological development 2.
• The use of computed tomography (CT) and magnetic resonance imaging (MRI) in pregnancy and lactation has increased, and guidelines have been developed for their use in selected indications, such as suspected acute appendicitis, pulmonary embolism, and renal colic 3.
• CT scans should be used with caution in pregnant women, and the benefits and risks of the procedure should be discussed with the patient before the scan is performed 3, 4.
• Fetal radiation doses up to 1 mGy are considered acceptable, but larger doses may increase the risk of carcinogenesis, although it remains low in absolute terms 5.
• The use of iodinated contrast agents is generally safe during pregnancy, but gadolinium-based contrast agents should be used with caution due to the lack of human clinical data and potential toxicity 5.
• The projected lifetime cancer risks from current computed tomography imaging are estimated to be approximately 103,000 future cancers over the course of the lifetime of exposed patients, with the largest number of cancers projected to result from abdomen and pelvis CT in adults 6.