Radiation dose and pregnancy

Pregnancy Questioning
Audit:
by Fathima Hasan Mohamed,
Senior Radiographer.

Introduction
• The imaging of pregnant women presents a unique challenge to
radiologists because of the concern about the radiation risk to the
conceptus (ie, embryo or fetus).
• Thousands of pregnant women are exposed to ionising radiation
each year
• Lack of knowledge is responsible for great anxiety and probably
unnecessary termination of pregnancies
• For most patients, radiation exposure is medically appropriate and
the radiation risk to the fetus is minimal.
 Lack of knowledge is responsible for great anxiety and
probably unnecessary termination of pregnancies
 For most patients, radiation exposure is medically appropriate and the
radiation risk to the fetus is minimal

Example: justified use of CT
Pregnant female, was in motor vehicle accident
Fetal
skull
ribs
Blood
outside
uterus
Fetal dose 20 mGy

AAH POLICY- EMERGENCY
INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION ——————————————————————————————————————
• During emergency, if informed consent cannot be
obtained or no relative is available to sign on behalf of the
patient, the physician shall clearly document in electronic
radiology requisition, the reason for the examination and
sign the consent. The radiologist will document the
reason for the examination and steps taken to minimize
risks to the embryo/fetus in the radiology report.

3 minute CT exam and taken to the
operating room. She and the child survived
Free blood
Kidney torn
off aorta (no contrast in it) Splenic laceration

Fetal radiation risk
 There are radiation-related risks throughout
pregnancy that are related to the stage of pregnancy
and absorbed dose
 Radiation risks are most significant during
organogenesis and in the early fetal period, somewhat
less in the 2nd trimester, and least in the 3rd trimester
Less Least
Most
risk

Radiation-induced malformations
 Malformations have a threshold of 100-200 mGy or
higher and are typically associated with central nervous
system problems
 Fetal doses of 100 mGy are not reached even with 3
pelvic CT scans or 20 conventional diagnostic x-ray
examinations
 These levels can be reached with fluoroscopically
guided interventional procedures of the pelvis and with
radiotherapy

Central nervous system effects
 During 8-25 weeks post-conception the CNS is
particularly sensitive to radiation
 Fetal doses in excess of 100 mGy can result in some
reduction of IQ (intelligence quotient)
 Fetal doses in the range of 1000 mGy can result in
severe mental retardation and microcephaly,
particularly during 8-15 weeks and to a lesser extent
at 16-25 weeks

Radiation Risk
 Radiation exposure that is extra-abdominal will not
contribute significant radiation dose to the developing
embryo/fetus.
 For most extra-abdominal exams, including CT, the
radiation dose to the embryo/fetus is less than 0.1 mSv (10
mrem).

Radiation Risk
 Radiation exposure that is extra-abdominal will not
contribute significant radiation dose to the developing
embryo/fetus.
 For most extra-abdominal exams, including CT, the
radiation dose to the embryo/fetus is less than 0.1 mSv (10
mrem).
 “The risk of malformation is increased only at
levels above 150 mSv (15 rem).”

Radiation Risk
 If the radiation dose is received between the second
and eighth post-conception weeks, therapeutic
abortion based solely on radiation exposure is not
advised for doses less than 150 mSv (15 rem).

Approximate fetal doses from
conventional x-ray examinations
Data from the UK, 1998
Dose
Examination
Mean (mGy) Maximum (mGy)
Abdomen 1.4 4.2
Chest <0.01 <0.01
Intravenous uro-
gram; lumbar spine
1.7 10
Pelvis 1.1 4
Skull;
thoracic spine
<0.01 <0.01

Approximate fetal doses from fluoroscopic and
computed tomography procedures
Data from the UK, 1998
Dose
Examination
Mean (mGy) Maximum (mGy)
Barium meal (UGI) 1.1 5.8
Barium enema 6.8 24
Head CT <0.005 <0.005
Chest CT 0.06 1.0
Abdomen CT 8.0 49
Pelvis CT 25 80

Clinical Imaging Institute
Audit: Pregnancy Questioning
.Objectives: To exclude the possibility of pregnancy in
female of childbearing age who are undergoing
radiography.
Audit Plan: Continuous
Place of study: Clinical Imaging Institute/Al Ain Hospital.
Duration of study: 4 months.
Sample size: 100 patients were evaluated in this study.

Data collection method
• Our local process is as follows:
• Female patients of childbearing age, who will undergo
x-ray procedures are screened for possibility of
pregnancy.
• They sign the consent form which is given to the
department secretary who then records the medical
record numbers in a logbook before it is sent to HIM
department to be filed in patients file.
• These forms are sent to HIM department on a weekly
basis.

Method
• Patients who had X-rays were identified through
the logbook kept with secretary and Cerner
online worklist .
• Data was compiled in table format and
descriptive analysis was performed.
• Study was focused on female patients age 12-
50.
• Consent was documented.

Pregnancy questioning audit- Type of
investigation

Pregnancy questioning audit-Area of
examination

Data Analysis and result:
• Percentages:
• 82% cases= CT
• 18% cases= Xray
• 38% cases where abdomen/pelvis area
examined.
• 62% cases ,away from the adomen/pelvis
area.

Discussion
• Study shows that CT section is more compliant with
documenting consent for their female patients as
compared to x-ray.
• Radiographer’s say that they enquire verbally and
document on Cerner.
• How safe is this practice?
• Consent form should include the signature of the staff
who has taken the consent as well. Forms to be filled
showing LMP date.

Guidelines:
• Based on the current knowledge, the following
guidelines should be adhered to;
• Routine examinations-28 day rule.
• For non-urgent examinations involving high doses to
uterus in patients who are at risk of pregnancy but not
yet overdue, - “10 day rule”
• Radiation exposure of the lower abdomen and pelvis of
women of childbearing potential should be kept to a
minimum. During pregnancy, radiation to these regions
should only occur if the radiological examination
cannot be postponed because of the urgent nature of
the investigation

Specific guidelines:
• Taken from Radiological Protection Institute of Ireland.
• The referring clinician has a responsibility to ensure
that the examination is justified and shall provide the
radiologist with all relevant information as part of the
examination request.
• For high dose examinations, involving greater than 10
mGy to the fetus, the 10 day rule should be applied4.
• For urgent examinations that are justified irrespective
of pregnancy status,a clinical waiver section within the
request, should be completed by the referring clinician.

Specific guidelines
• When a female patient of reproductive capacity presents for any
radiological procedure involving ionizing radiation, the following
process should be applied:
• The patient should be explicitly asked by the radiologist, the
radiographer or the radiology nurse, whether she is or might be
pregnant and her answer should be recorded in writing. The
record should be kept according to local protocol. The date of
the first day of the last menstrual period (LMP) of the patient
should be recorded.
• A brief but simple explanation should follow, such as: “I have to
ask because radiation in pregnancy may increase the risk of
childhood cancer above the natural baseline level”
• The examination may proceed if the patient states that she is
not pregnant and has signed a consent form.

Specific guidelines
• When a patient answers that she: is pregnant, or might be
pregnant or cannot exclude the possibility of pregnancy and the
menstrual period is overdue the referring clinician should be
asked to review the justification for the examination, bearing in
mind the possible presence of a fetus.
• When there is definite pregnancy, or potential for an unknown
• pregnancy, the review of justification should consider the
following:
• n Is there a suitable alternate approach to imaging using non-
ionising radiation, e.g. ultrasound or magnetic resonance?

Specific guidelines
• Is the examination critical to immediate and essential patient
management, or could management proceed if the examination
is deferred until pregnancy can be completed or definitely
excluded?
• Is the likely fetal radiation dose and risk of the examination
greaterthan the benefit of the examination and/or greater than
the risk incurred by not doing the examination?
• The use of contraception does not rule out pregnancy. Whilst
contraceptive use mitigates against the likelihood of pregnancy,
the efficacy of the method used is a matter for professional
judgment and where there is doubt, these guidelines should be
followed.

Specific guidelines
• When an examination is justified during pregnancy or
when pregnancy cannot be ruled out, all accepted
methods of optimising the examination and reducing
the dose delivered should be applied.
• Additional guidance:
• A clearly displayed multi-lingual notice briefly
explaining the importance of declaring a pregnancy
before an X-ray examination is recommended.
• For non-English speaking patients, the hospital
interpretation services should be used.

Suggestions:
• Do we have enough signage? Increase the
number and distribution of posters and patient
information leaflets to create awareness about
pregnancy and radiation.
Ability to scan the consent forms into PACS would
greatly facilitate such an audit.

Video

Conclusion
• Radiographic, fluoroscopic, and CT examinations in
areas of the body other than the abdomen and pelvis
deliver minimal radiation doses to the fetus.
• Radiographic, fluoroscopic, and CT examinations of
the abdomen and pelvis and from nuclear medicine
studies rarely exceed 25 mGy.
• While this information may reassure pregnant women
and their physicians about the risks from necessary or
unintended radiation exposures, conservative clinical
management is the best way of minimizing radiation
risk in utero.

References
• 1. International Commission on Radiological Protection. Statement from
the 1983 Washington meeting of ICRP. Annals of International Commission
on Radiological Protection 1984:14
• 2. National Radiological Protection Board. Exposure to ionizing radiation of
pregnant women: advice on the diagnostic exposure of women who are, or
who may be pregnant. ASP8.NRPB, 1985.
• 3. College of Radiographers and Royal College of Radiologists. Guidelines
for implementation of ASP8.NRPB, 1986.
• 4. National Radiation Protection Board. Board statement on diagnostic
medical exposure to ionising radiation during pregnancy and estimates of
late radiation risks to the UK population. Documents of the NRPB 1993;
4(4):1-14.

Web sites for additional information
on radiation sources and effects
European Commission (radiological protection pages):
europa.eu.int/comm/environment/radprot
International Atomic Energy Agency:
www.iaea.org
International Commission on Radiological Protection:
www.icrp.org
United Nations Scientific Committee on the Effects of
Atomic Radiation:
www.unscear.org
World Health Organization:
www.who.int

Radiation dose and pregnancy

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