No-call cell-free DNA result in a higher-risk pregnancy — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar on the antenatal liaison round. Aisha is 37 years old at 11 weeks gestation. Her cell-free DNA screen returns a no-call result due to low fetal fraction. She asks whether the baby is fine and whether she needs any further testing. She lives two hours from the nearest diagnostic service, has intermittent phone reception and limited leave from work. You have 12 minutes with the patient and 5 minutes for examiner discussion. [1] [18]

Information available on request

• First pregnancy, conceived spontaneously; no relevant family history; no consanguinity. [1]
• Body mass index 34; no chronic illness; non-smoker. [1] [16]
• Cell-free DNA taken at 10 weeks; laboratory reports a no-call due to fetal fraction below the reportable threshold. [1] [16]
• Nearest diagnostic service (chorionic villus sampling and amniocentesis) is at the regional base hospital. [11]
• Preferred language English; intermittent mobile reception at home; one car in the household. [18]

Tasks

1. Explain a no-call result in plain language without equating it with a low-risk result. [1] [16]
2. Outline the management options (repeat screen, diagnostic testing, surveillance) and the factors that guide the choice. [1] [11]
3. Address the misconception that "no result means the baby is fine." [16]
4. Design a capability-matched rural follow-up and safety-net plan with a named owner. [18]

Marking anchors

Must-hit

• States that a no-call is not the same as a low-risk result and carries its own risk. [1] [16]
• Offers the full option set (repeat cell-free DNA, diagnostic testing, detailed ultrasound with surveillance) rather than reassurance alone. [1]
• Quotes contemporary, not legacy, procedure-related risk if diagnostic testing is discussed. [11]
• Names an owner, contact path and backup number, and accounts for transport and reception reality. [18]
• Counsels non-directively and uses teach-back. [18]

Merit

• Links low fetal fraction to raised body mass index and to the possibility of aneuploidy or growth restriction as the biological basis of the no-call. [1] [8]
• Discusses how pre-test probability (age, body mass index) shapes the choice between repeat and diagnostic testing. [16]
• Plans interpreter or cultural support proactively if applicable. [18]

Fail

• Tells the patient the baby is fine because the test could not be completed. [1] [16]
• Discharges with no booked next step or named owner. [18]
• Pressures the patient into a decision without information or time. [18]