Congenital lung and airway malformations — structured oral (viva)

Branch 1 — Antenatal risk stratification

Examiner: "You are the fetal-medicine registrar. How do you decide how worried to be about this lesion?" Candidate: The raw size matters less than its physiological effect, so I focus on the mediastinal shift, the compression of the heart and great veins, and any early signs of hydrops such as skin oedema, ascites or a pericardial effusion. I would quantify the lesion using the CPAM volume ratio, a size index that predicts the risk of hydrops and directs how intensively the pregnancy is monitored, and I would follow it with serial ultrasound. A large solid microcystic lesion with a rising volume ratio and early hydrops marks this fetus as high risk. [1] [2]

Branch 2 — Fetal therapy

Examiner: "The volume ratio is high and hydrops is developing. What can be offered before birth?" Candidate: For a large predominantly microcystic lesion driving hydrops, a course of maternal corticosteroid can shrink the lesion and reverse early hydrops, and this is now a first-line antenatal intervention. If a dominant macrocyst is present it can be drained or a thoracoamniotic shunt placed, and the most severe hydropic lesions may be considered for open fetal surgery at a specialist centre. All of this requires urgent referral to a fetal-medicine unit that can deliver these interventions. [3] [1]

Examiner: "Why does hydrops change everything?" Candidate: Because hydrops signals that the mass is impairing venous return and cardiac output, and untreated it carries a very high risk of fetal death. Reversing it — most often with maternal steroids for a microcystic lesion — is the single intervention most likely to change survival, which is why recognising early hydrops and acting on it promptly is the crux of antenatal management. [3] [2]

Branch 3 — Delivery and neonatal stabilisation

Examiner: "The pregnancy reaches term and the baby is born in respiratory distress. How do you manage the first hour?" Candidate: I would resuscitate on standard airway, breathing and circulation lines but with caution about positive pressure, because a large air-trapping lesion can over-distend when pressurised and worsen mediastinal shift and cardiorespiratory compromise. I would give oxygen, support gently, obtain urgent imaging, and involve senior anaesthetic and paediatric surgical teams immediately, because definitive relief of a symptomatic lesion is surgical decompression or resection rather than escalating ventilator settings. [1] [4]

Branch 4 — Definitive management and why it matters

Examiner: "What is the definitive management, and why not simply watch even this lesion?" Candidate: A symptomatic lesion is resected, usually by lobectomy and increasingly thoracoscopically, and resection both relieves the distress and removes the reservoir for future infection and malignant change. Even were it less symptomatic, the recognised association between some cystic lesions and pleuropulmonary blastoma means an atypical lesion warrants resection and pathological review rather than indefinite watching, and a DICER1 family history would lower my threshold further. I would arrange structured follow-up and confirm good long-term lung function is expected after infant lobectomy. [4] [1]