Pregnancy: x-ray studies for detection of thromboembolism caused little harm to foetuses.

Clinical bottom line (level 2a)

  1. Babies exposed to low dose radiation in utero were slightly more likely to develop cancer (NNH = 5000 at unknown) .
  2. The teratogenic risks are probably even smaller.
Ginsberg et al: Thrombosis and Haemostasis 1989; 61 (2): 189-196
Expires May 2003

The study

Systematic review of all of
  • Patients: pregnat women
  • Intervention: receiving low radiation doses (<5 rads) for detection of venous thromboembolism
  • Outcome: oncogenicity and teratogenicity


    • Articles found in ? using MEDLINE, 1966 to 1987 (search terms: MeSH terms: radiation effects; abnormalities, radiation induced; leukemia, radiation induced; teratogenic; maternal-fetal exchange; pregnancy; fetus ) and bibliographies from pertinent articles were searched

    Selection criteria: as above
    Appraisal criteria: no set criteria
    Articles excluded if: not human studies

    Eleven retrospective cohort/case-control studies found on oncogenicity. Eighteen retrospective cohort studies on teratogenicity.
    • Radiation doses for venography and pulmonary angiography were calculated using measurements of skin exposure rates and published organ dose tables.

    The evidence

    • Radiation doses per investigations:
      • contrast venography= 0.314 rads
      • pulmonary angiography= 0.221 to 0.374 rads
    • Oncogenicity for doses < 0.5 rads:
      • RR ranged from 1.2 to 1.7 (no confidence intervals given)
      • NNH=~5000, assuming cancer rate of 0.1% in neonates
    • Teratogenicity for doses < 0.5 rads: no increase noted in:
      • death
      • growth, head size or mental retardation
      • congenital malformations

    Comments

    1. Practically, duplex ultrasound is more likely to be the investigation of first choice for DVT.
    2. Even combined studies are too small to clearly demonstrate any small increase in harm from radiation exposure in utero.

    Citation

    1. Ginsberg JS, Hirsh J, Rainbow AJ, et al: Risks to the fetus of radiologic procedures used in the diagnosis of maternal venous thrombembolic disease. Thrombosis and Haemostasis 1989; 61 (2): 189-196
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer: Paul Flynn

    Clinical Question.
    Patient pregnant women with suspected thromboembolic disease
    Intervention or Exposure low radiation doses for in-utero study
    Outcome oncogenicity and teratogenicity