Eating disorders: recognition and medical instability — OSCE communication and clinical station

Candidate instructions

You are the paediatric registrar in the emergency department. You have two eight-minute stations. In Station A, a 15-year-old cross-country runner has fainted at school; she is with her mother. In Station B, you see a 16-year-old alone who reports palpitations and weakness, and her mother (in the waiting area) says she goes to the bathroom straight after meals. [2] [3]

Station A — Fainting runner with her mother

Candidate brief

Assess the adolescent, recognise the eating disorder, apply a screen, perform the instability assessment, identify red flags, and communicate a clear plan to the adolescent and her mother. [2]

Encounter

Greet the adolescent first, then her mother; set the frame and ask to spend time alone with the young person, stating conditional confidentiality with honest limits. Take a focused eating, exercise, menstruation and mood history alone; apply SCOFF. Weigh in a gown, measure vital signs including a standing test, temperature, and obtain a 12-lead ECG. Recognise atypical anorexia (she meets full anorexia criteria at a non-low weight) and the red flags (bradycardia and a marked postural heart-rate rise). [1] [3]

Marking domains

• Recognition and screening (25%): identifies restriction, driven exercise, amenorrhoea and syncope as an eating disorder; applies SCOFF and states the two-or-more threshold; recognises atypical anorexia. [1]
• Instability assessment (30%): performs the standing test and identifies bradycardia and the postural heart-rate rise; requests an ECG; weighs and plots. [3] [4]
• Clinical reasoning and red flags (25%): lists the red flags that mandate admission and correctly judges this patient unstable. [3]
• Communication (20%): engages the adolescent and her mother without judgement; explains that the illness is serious but treatable; does not reassure on the basis of a "healthy" weight. [2]

Station B — Normal-weight adolescent with vomiting and palpitations

Candidate brief

Recognise bulimia nervosa at a normal weight, identify the electrolyte-driven arrhythmia risk, order the focused investigations, and arrange multidisciplinary care with explicit suicide-risk screening. [2]

Encounter

See the adolescent alone with a HEEADSSS frame; ask about binges, vomiting, laxatives, exercise, mood and self-harm; apply SCOFF. Examine for bradycardia, Russell's sign, parotid enlargement and dental erosion. Order a 12-lead ECG and electrolytes (expect hypokalaemia with metabolic alkalosis), magnesium, phosphate and glucose. Explain the mechanism (purging causes hypokalaemia, which prolongs repolarisation and causes the palpitations and faint), and that the QTc and potassium determine whether admission is needed. Screen explicitly for suicidality. [2] [6]

Marking domains

• Recognition (30%): identifies bulimia nervosa despite a normal weight; recognises Russell's sign and parotid enlargement. [6]
• Investigations and mechanism (30%): requests an ECG and electrolytes; explains hypokalaemia-driven repolarisation abnormality. [6]
• Disposition and multidisciplinary care (20%): admits if the QTc is prolonged or potassium is low; refers to specialist eating-disorder mental-health care. [2]
• Suicide-risk and safety (20%): screens for self-harm and suicidality and uses a crisis pathway if risk is high. [2]

Examiner notes

• The common failure is reassurance on the basis of a "healthy" or "normal" weight in both atypical anorexia and bulimia. [2]
• A candidate who omits the standing test or the ECG should lose marks in both stations. [3] [4]
• Family-based treatment is first-line for adolescent anorexia; cognitive-behavioural therapy adapted for eating disorders is first-line for bulimia. [2]