Guidelines for Diagnostic Imaging During Pregnancy

American College of Obstetricians and Gynecologists.

ACOG Committee Opinion No. 299.

Obstet Gynecol 2004;104:647–51.

Schematic presentation of the various adverse effects associated with radiation and their relative incidence at different stages of gestation.  (Adapted from Mettler FA Jr, Upton A [eds]: Medical Effects of Ionizing Radiation, 2nd ed. Chapter 8. Philadelphia, WB Saunders, 1995.)

Stages of Fetal Development

Development of the unborn child is expressed as postconception age and can be divided approximately into three major phases:

1. The pre-implantation/implantation phase

0–2 wk, from conception to implantation

2. The phase of major organogenesis

3rd–8th wk

3. The phase of fetal development

from 9th weeks until birth

Risks and Threshold Doses of the Main Effects of Prenatal IrradiationGestational

AgeStage

Potential Biologic Effect

Threshold Risk

0–2 wkPreimplantation

/implantation

Abortion >10 rad  

Organ malformation

>5; >10 rad  

3–7 wk OrganogenesisGrowth

retardation>10 rad  

8–25 wk Fetal

Growth retardation

>10 rad  

Mental impairment

>10 rad  

Whole pregnancy

 Carcinogenesis None 6 ? 10−4 per rad

Mutagenesis None 1 ? 10−2 per rad

Modified from Fattibene P, Mazzei F, Nuccetelli C, Risica S: Prenatal exposure to ionizing radiation: Sources, effects, and regulatory aspects. Acta Paediatr 88:693, 1999.

 Estimated Fetal Exposure for Diagnostic Images

Examination Type Estimated Fetal Dose per Examination (rad)

Number of Examinations Required for Cumulative 5-rad Dose

Plain Films

Skull 0.004 1,250

Dental 0.0001 50,000

Cervical spine 0.002 2,500

Upper or lower extremity 0.001 5,000

Chest (2 views) 0.00007 71,429

Mammogram 0.020 250

Abdominal 0.245 20

Thoracic spine 0.009 555

Lumbosacral spine 0.359 13

Intravenous pyelogram 1.398 3

Pelvis 0.040 125

Hip (single view) 0.213 23

 Estimated Fetal Exposure for Diagnostic Images

Examination Type Estimated Fetal Dose per Examination (rad)

Number of Examinations Required for Cumulative 5-rad Dose

CT Scans (Slice Thickness: 10 mm)

Head (10 slices) <0.050 >100

Chest (10 slices) <0.100 >50

Abdomen (10 slices) 2.600 1–2Lumbar spine (multiple views) 3.500 1–2

Pelvimetry (1 slice with scout film) 0.250 20

Key Statements on Diagnostic Imaging Modalities during Pregnancy

X-Ray Imaging

Magnetic Resonance Imaging

Ultrasound Imaging

X-Ray Imaging

“No single diagnostic procedure results in a radiation dose that threatens the well-being of the developing embryo and fetus.”

American College of Radiology;

Scientific view of low-level radiation risks. Radiographics 11:509, 1991.

“ Fetal risk is considered to be negligible at 5 rad or less when compared to the other risks of pregnancy, and the risk of malformations is significantly increased above control levels only at doses above 15 rad.”

National Council on Radiation Protection and Measurements;

Medical Radiation Exposure of Pregnant and Potentially Pregnant Women.

NCRPM Report No. 54. Bethesda, MD, NCRPM, 1977.

“Women should be counseled that x-ray exposure from a single diagnostic procedure does not result in harmful fetal effects. Specifically, exposure to less than 5 rad has not been associated with an increase in fetal anomalies or pregnancy loss.”

American College of Obstetricians and Gynecologists,Committee on Obstetric Practice;

Guidelines for Diagnostic Imaging During Pregnancy. ACOG Committee Opinion No. 299.

ACOG, September 2004.

Magnetic Resonance Imaging

“Although there have been no documented adverse fetal effects reported, the National Radiological Protection Board arbitrarily advises against its use in the first trimester.”

American College of Obstetricians and Gynecologists, Committee on Obstetric Practice;

Guidelines for Diagnostic Imaging During Pregnancy. ACOG Committee Opinion No. 158.

ACOG, 1995.

Ultrasound Imaging

“There have been no reports of documented adverse fetal effects for diagnostic ultrasound procedures, including duplex Doppler imaging.”

“There are no contraindications to ultrasound procedures during pregnancy, and this modality has largely replaced x-ray as the primary method of fetal imaging during pregnancy.”

American College of Obstetricians and Gynecologists, Committee on Obstetric Practice;

Guidelines for Diagnostic Imaging During Pregnancy. ACOG Committee Opinion No. 299.

ACOG, September, 2004.

Guidelines for Diagnostic Imaging during Pregnancy

American College of Obstetricians and Gynecologists.

ACOG Committee Opinion No. 299.

Obstet Gynecol 2004;104:647–51.

Women should be counseled that x-ray exposure from a single diagnostic procedure does not result in harmful fetal effects.

Specifically, exposure to <5 rad has not been associated with an increase in fetal anomalies or pregnancy loss.

Concern about possible effects of high-dose ionizing radiation exposure should not prevent medically indicated diagnostic x-ray procedures from being performed on a pregnant woman.

During pregnancy, other imaging procedures not associated with ionizing radiation (ultrasonography and MRI) should be considered instead of x-rays when appropriate.

Ultrasonography and MRI are not associated with known adverse fetal effects.

Consultation with an expert in dosimetry calculations may be helpful in calculating estimated fetal dose when multiple diagnostic x-rays are performed on a pregnant patient.

The use of radioactive isotopes of iodine is contraindicated for therapeutic use during pregnancy.

Radiopaque and paramagnetic contrast agents are unlikely to cause harm and may be of diagnostic benefit, but these agents should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.