Primary ciliary dyskinesia — branching viva

Station opening

Examiner: "Define primary ciliary dyskinesia and outline how you would classify it." [4]

Strong candidate (must-hit)

• Defines PCD as an inherited, usually autosomal recessive, defect of motile cilia that fails mucociliary clearance across the airways, sinuses and middle ear; classifies it by ciliary ultrastructural defect (outer dynein arm defect commonest, central apparatus and radial spoke defects that may have normal electron microscopy) and by situs (about half normal, about half situs inversus, a small heterotaxy group); and names Kartagener syndrome as situs inversus with chronic sinusitis and bronchiectasis, noting it is a subset of PCD. [4] [1]

Weak candidate

• "It is Kartagener syndrome, which is when the organs are the wrong way round." [4]

Branch A — The 4-year-old with a wet cough and dextrocardia

Examiner: "A 4-year-old has a daily wet cough since infancy and the heart is on the right. How do you confirm the diagnosis and what must you exclude?" [1] [2]

Strong

• Recognises probable PCD (Kartagener syndrome given situs inversus); confirms in a specialist centre using a combination of nasal nitric oxide as a screen, high-speed video microscopy, transmission electron microscopy and genetic testing because no single test suffices; and actively excludes cystic fibrosis with a sweat chloride test, remembering that cystic fibrosis can also lower nasal nitric oxide. [1] [2]

Weak

• "I would reassure the family that dextrocardia is harmless and treat the cough with a bronchodilator." [4]

Branch B — The term neonate with respiratory distress and situs inversus

Examiner: "A term newborn has unexplained respiratory distress and situs inversus. Why does this matter for PCD?" [4] [2]

Strong

• Identifies that unexplained neonatal respiratory distress in a term infant is one of the earliest and most specific clues to PCD, especially with situs inversus; stabilises the baby with oxygen and respiratory support while investigating the cause; and plans respiratory follow-up and later diagnostic testing rather than attributing everything to transient tachypnoea, because acting on this presentation brings the diagnosis forward by years. [4] [2]

Weak

• "Neonatal distress is common and unrelated; I would not think about PCD at this age." [2]

Branch C — The 8-year-old with confirmed PCD who has grown Pseudomonas

Examiner: "An 8-year-old with confirmed PCD grows Pseudomonas for the first time and his lung function is declining. What do you do?" [5] [9]

Strong

• Treats new Pseudomonas with an eradication protocol rather than allowing chronic colonisation, intensifies daily airway clearance, ensures prompt culture-directed treatment of exacerbations and regular surveillance cultures and spirometry, and considers maintenance azithromycin to reduce exacerbations, citing the BESTCILIA trial while excluding non-tuberculous mycobacterial infection before starting. [5] [9]

Weak

• "Pseudomonas is expected in these children, so I would leave it and repeat the culture later." [5]

Branch D — The child with situs ambiguus found on workup

Examiner: "During a PCD workup you find situs ambiguus rather than situs inversus totalis. Why does that change things?" [7] [4]

Strong

• Explains that situs ambiguus or heterotaxy is not a harmless mirror image and carries a real risk of complex congenital heart disease and functional asplenia; arranges an echocardiogram, assesses splenic function, and where the spleen is absent or non-functional provides pneumococcal and other vaccination and antibiotic prophylaxis with a low threshold for treating febrile illness as sepsis; and coordinates respiratory, cardiology and surgical care. [7] [4]

Weak

• "Situs ambiguus is the same as situs inversus, so nothing changes." [7]

Close

Examiner: "Summarise your approach to the child with suspected PCD in one sentence." [1] [9]

Strong

• "I recognise the phenotype early — neonatal distress in a term baby, a daily wet cough from infancy, chronic sinusitis and otitis media, and situs inversus in about half — refer to a specialist centre for combined nasal nitric oxide, video microscopy, electron microscopy and genetics while excluding cystic fibrosis, and manage it lifelong with daily airway clearance, surveillance cultures with prompt culture-directed antibiotics and Pseudomonas eradication, azithromycin to cut exacerbations, and joint ENT, audiology and genetic care." [1] [9]