Diagnostic Imaging During Pregnancy

Let’s talk about x-rays and CT scans in pregnancy. Sometimes situations arise where an illness can be potentially serious or urgent. In general, with X-rays and CT scans the dose of radiation is unlikely to cause any ill effects on a pregnancy after the early weeks. Ultimately, the most important factor in having a healthy baby is ensuring a healthy mother, because the baby depends on the mother to stay well and carry her pregnancy to term.

Possible effects of acute doses of radiation and estimated threshold doses.

Gestational Age Possible effect 1 mGy 10 mGy 50 mGy 500 mGy
Threshold dose (mGy)
Up to 1 week Miscarriage Nil Nil Nil Possible 100
2–6 weeks Miscarriage Nil Nil Nil Possible 250–500
Gross malformations Nil Nil Nil Possible 200
10–17 weeks Mental retardation Nil Nil Nil 20% None
IQ score decline 15 points Non-threshold
Gross malformations Nil Nil Nil Possible 500
18–27 weeks Mental retardation Nil Nil Nil 5% 120
IQ score decline 4 points 120
Throughout pregnancy Fetal growth restriction Nil Nil Nil Possible 200–250

Estimated fetal exposure for plain X-rays

Examination type
Estimated fetal dose per examination (1 mGy = 1 mSv)
Skull <0.0005
Dental 0.001
Cervical spine 0.02
Upper or lower extremity 0.01
Chest 2–7/104
Abdominal 1.4–4.2
Thoracic spine 0.09
Lumbosacral spine 1.7–10
Pelvis 1.1–4
Mammogram 0.2–0.7
Intravenous pyelogram 10–40
Retrograde pyelography 6

Estimated fetal exposure for computed tomography

Examination type
Estimated fetal dose per examination (1 mGy = 1 mSv)
Head 0.005
Chest 0.06–0.16
Chest angiography 0.0035–0.131
Abdomen 8–30
Lumbar spine 0.9–7.5
Pelvis 25–79
Pelvimetry 0.2–0.4

 

Source Data from : Eskandar OS, Eckford SD, Watkinson T. Safety of diagnostic imaging in pregnancy. Part 1: X-ray, nuclear medicine investigations, computed tomography and contrast media. The Obstetrician & Gynaecologist 2010;12:71–78.

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