Perplexing presentations and diagnostic uncertainty — branching viva

Opening

Examiner: A seven-year-old boy is referred to you after two years of recurrent vomiting, lethargy and fainting episodes. He has been seen at four hospitals, has had repeated blood tests, two endoscopies and a CT, and is on two medications. His parents give different histories. His school attendance is under 30%. His mother is asking you to insert a feeding tube. How do you frame this? [5]

Candidate: I would frame this as a perplexing presentation — a clinical situation in which the reported symptoms, signs and findings are not adequately explained by any recognised disease, but in which there is not yet objective evidence of harm or falsification. The RCPCH describes this as the middle of a three-level escalation: alerting signs raise concern, the perplexing presentation triggers structured assessment, and fabricated or induced illness is the child-protection end. My job is to hold three limbs in parallel — a genuine rare or complex organic disease, a medically unexplained or functional disorder, and a safeguarding concern — and to resist the two opposite errors: dismissing genuine disease, or jumping to an abuse label without evidence. I would not agree to a feeding tube today. [5]

Branch 1 — the balanced differential

Examiner: Walk me through how you build the three-limb differential. [5]

Candidate: For the organic limb, I look for reproducibility on independent observation, objective findings between episodes, a trajectory consistent with a known disease, and a response to disease-directed treatment. For the functional or somatising limb, I look for a consistent functional pattern, a personal or family history of somatisation or anxiety, normal objective findings throughout, and a positive response to a functional explanation and rehabilitation. For the safeguarding limb, I look for symptoms present only in one caregiver's presence, discrepancies across records from different centres, objective absence on separate observation, and escalating, unjustified intervention causing iatrogenic harm. None of these limbs is mutually exclusive — a child may have a real, mild disease overlaid by exaggeration, or a somatising adolescent who is also being harmed. [5] [3]

Examiner (probe): What is the single most discriminating action you can take? [5]

Candidate: Separate observation of the child, where clinically and ethically appropriate — because symptoms that vanish in the caregiver's absence, or findings that cannot be reproduced on the ward, fundamentally reshape the differential in all three limbs at once. It does not by itself diagnose anything, but it is the most powerful single move. [5] [7]

Branch 2 — the investigation strategy

Examiner: He has already had a lot of tests. How do you decide what to investigate next? [6]

Candidate: The first step is not to order a new test but to obtain and review every prior record from every centre — the Singh multisite survey showed that the commonest process breakdown in paediatric diagnostic error is failure to gather information through history, examination and chart review. Then I investigate judiciously: each test linked to a named item on the differential, justified and time-limited. I would not order a blanket screen, because the blanket screen is how the investigation spiral begins and how iatrogenic harm accrues. Given the multisystem and atypical picture, I would seek a single genetics or metabolic opinion rather than sequencing individual system workups, because that is the route that ends the diagnostic odyssey for many rare diseases. The Wong Duchenne study showed that the diagnostic odyssey for rare paediatric diseases routinely runs to years and causes measurable harm. [6] [4]

Examiner (probe): And for the functional limb? [8]

Candidate: The key step for the functional limb is to stop investigating once a positive functional diagnosis is made, and to make that diagnosis explicitly. A functional disorder is diagnosed by its characteristic positive pattern, not by exclusion, and the offer of coordinated rehabilitation is both the diagnostic confirmation and the first treatment. Re-investigating "to be sure" once the functional pattern is clear is the commonest cause of iatrogenic harm in this limb. [8] [3]

Branch 3 — the management pathway

Examiner: How do you actually run the management? [5]

Candidate: The definitive response is a balanced, safety-netted pathway run by one multidisciplinary team, not a sequence of independent consultations. I identify one named consultant to own the child's care, hold the records and coordinate the plan — fragmentation is the structural enabler of harm, and a single owner is the structural antidote. I stabilise, gather and verify, examine and document, investigate judiciously, hold the differential explicitly open in writing, and give the family an explicit, dated safety-net. I assess the child's function — school, friendships, mobility, feeding, development — because the narrowing of daily life is itself the measure of harm, and its recovery is the measure of success. A child whose school attendance has collapsed and who is accumulating invasive interventions is being harmed by the situation regardless of its ultimate cause. [5] [6]

Examiner (probe): The mother is very distressed and demanding. How do you handle that? [1]

Candidate: I would listen, acknowledge her distress, and convey the uncertainty honestly — families who have been bounced between teams value a clinician who owns the uncertainty, names the plan and gives a clear route back. I would not agree to interventions without a named clinical indication, and I would explain that the accumulating medical response can itself be the harm. I would engage senior staff and the named safeguarding lead early, because managing a perplexing presentation is demanding and the family's distress is often intense. [1] [7]

Branch 4 — escalation and the referral

Examiner: When do you escalate to a child-protection referral? [1]

Candidate: I make the child-protection referral when I form a reasonable belief that the child has suffered or is at risk of significant harm, applying my jurisdictional threshold. The trigger is a reasonable belief of harm — not diagnostic certainty, and not a completed investigation. I would convene a case conference bringing together paediatrics, mental health, social work, primary care, education and, where relevant, law enforcement. The cardinal rule is not to confront the caregiver before the safeguarding and multidisciplinary plan are in place, because confrontation can precipitate escalation or flight. The clinical focus is the harm to the child, not the motive of the caregiver — getting the language right is part of getting the response right, which is why we moved from "Munchausen syndrome by proxy" to "fabricated or induced illness". [1] [2]

Examiner (final corner): And the prognosis? [5]

Candidate: Prognosis is best understood as the trajectory of the child's function, not a single diagnosis. Children whose perplexing presentation is met with a balanced, early, safety-netted plan do better, whether the answer turns out to be a treatable disease, a functional disorder that responds to rehabilitation, or a safeguarding situation that is addressed. The strongest protective factor is a stable, consistent, trusted relationship with a clinician and a team who hold the plan and the uncertainty together. Recurrence and relapse are common when the situation returns unchanged, which is why the written safety-plan, the named consultant and the fixed review date are not optional. [5] [8]