Newborn examination and screening — formative SAQs

SAQ 1 (10 marks)

A well term newborn is examined at 26 hours of age. The red reflex is normal. Pulse oximetry shows a right-hand saturation of 96% and a foot saturation of 88%. ^{[1] [19]}

1. State the pulse-oximetry screening result and justify your reasoning. (3) ^[1]
2. Outline your immediate clinical actions. (4) ^{[1] [2]}
3. What underlying physiology explains why a duct-dependent lesion can be missed on clinical examination alone? (3) ^{[1] [2]}

Model answer

1. The screen is positive. A foot saturation under 90 per cent is a positive screen on its own; the 8 per cent hand-to-foot differential also exceeds the 3 per cent threshold. ^[1]

2. Repeat the pulse oximetry. If it remains abnormal, examine the baby clinically (colour, effort, murmurs, femoral pulses), arrange urgent echocardiography, and refer to cardiology. If the baby is unwell or duct-dependent disease is suspected, start an intravenous prostaglandin E1 (alprostadil) infusion to keep the ductus open and prepare to support breathing. ^{[1] [2]}

3. Duct-dependent lesions are survivable while the ductus arteriosus remains open, shunting blood to the lungs or body. As the duct closes over the first days, the baby decompensates, often having looked completely well beforehand. The clinical examination alone misses these babies before collapse, which is why pulse oximetry screening was introduced. ^{[1] [2]}