Possible Early Pregnancy and a Routine Lumbar Spine Request
A 26-year-old woman attends the orthopaedic outpatient department with three weeks of mechanical low back pain and no red flags. The orthopaedic surgeon has requested lumbar spine AP and lateral radiographs before prescribing physiotherapy. At the reception desk she says her periods are irregular and she cannot remember her last menstrual period; she thinks she might be about five weeks pregnant. No urine pregnancy test has been done, and the referral form does not mention pregnancy. The OPD closes in one hour, and the surgeon has written 'routine, no delay' on the request. The radiographer has a lead apron and a 0.5 mm lead-equivalent shield but no written local protocol for pregnancy checks. The patient is anxious and asks whether the X-ray will harm the baby. The department has a CR system and the exposure for a lumbar spine AP is 70 kVp, 20 mAs at 100 cm SID.
1. What should you do before exposing the patient, given the possible pregnancy and the surgeon's instruction? Explain the ethical and radiation-protection reasoning.
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I would not proceed immediately just because the request says 'routine, no delay'. The examination is non-urgent, and the patient may be in early pregnancy.
Steps:
- Explain to the patient that the X-ray dose to the abdomen is low but not zero, and that because her periods are irregular we need to clarify whether she is pregnant before a routine lumbar spine examination.
- Offer a urine pregnancy test with her consent, or contact the surgeon to discuss whether the examination can be deferred until pregnancy is confirmed or excluded.
- Explain that the '10-day rule' is a practical way of reducing the chance of irradiating an early pregnancy for non-urgent abdominal or pelvic examinations; with irregular periods it cannot be applied reliably, so testing is better.
- Document the possible pregnancy, the discussion, the decision and the time. If the patient declines testing, record her informed choice.
Reasoning: justification and ALARA require that the benefit of a routine examination outweigh the risk. A lumbar spine radiograph is not an emergency, and the surgeon's convenience cannot override the need to clarify pregnancy status. Patient autonomy also requires that she understands the issue and participates in the decision.
2. If the surgeon confirms that the examination is clinically necessary, how would you optimise the technique and protect the fetus?
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I would first confirm the pregnancy status and document the discussion. If the examination is genuinely necessary, I would optimise rather than simply cancel:
- Use the 0.5 mm lead-equivalent shield over the lower abdomen and pelvis, positioned so that it does not obscure the lumbar spine. The shield reduces fetal dose from scattered radiation, but it cannot replace collimation.
- Collimate tightly to the lumbar spine for both AP and lateral views, using the smallest field that includes the vertebrae and disc spaces.
- Use the CR system's optimal speed and processing so that a repeat is not needed. Keep the 100 cm SID and use the department's exposure chart; 70 kVp and 20 mAs is a reasonable starting point, but I would adjust to the patient's size and check the image before deciding on any repeat.
- Limit the study to the requested views and avoid extra projections such as oblique views unless specifically justified.
- Ask the radiologist whether a PA projection or a lower-dose technique would be acceptable; for lumbar spine, AP is routine, but the principle is to avoid unnecessary exposure.
- If there is doubt about fetal dose, ask the radiologist or medical physicist to estimate it rather than guessing. Document the shield, collimation and number of exposures.
3. How would you explain the risk to this anxious patient and document her consent?
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I would use plain language: explain that the X-ray beam is directed at the lower back, that the shield and tight collimation reduce scatter to the abdomen, and that the dose to the baby from a lumbar spine X-ray is low. I would avoid saying 'there is no risk' because that is not accurate; I would say the risk is small and that the examination is being done only because the surgeon considers it necessary.
I would then:
- Invite her questions and check that she understands.
- Explain the alternative of delaying the examination until pregnancy is excluded, if the surgeon agrees.
- Obtain and document her consent, including that she understands the small risk and the reason for proceeding.
- Record the shield used, the collimation, the number of exposures and the advice given.
- Tell her she should inform her antenatal care provider that she had a lumbar spine X-ray, so that the information is available if needed.
This approach respects her autonomy, avoids coercion and leaves a clear record of the justification for the exposure.