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]

SAQ 2 (10 marks)

A term newborn has a normal cardiovascular and respiratory examination. The red reflex is normal. The hips show a clunk on Barlow's manoeuvre. There is also a 4 mm deep sacral dimple within the gluteal cleft with no other skin stigmata. [5] [19]

1. Interpret the hip finding and distinguish it from a benign click. (3) [5] [6]
2. Outline the management of the hip finding, including the role of risk factors. (4) [5]
3. Interpret the sacral dimple and state what, if any, investigation is required. (3) [15] [16]

Model answer

1. A clunk on Barlow's manoeuvre is the femoral head dislocating out of the acetabulum on posterior pressure — a positive sign for developmental dysplasia of the hip. A click is a high-pitched, ligamentous snap and is benign. The discriminator is the clunk, not the click. [5] [6]

2. A positive Barlow sign indicates an unstable hip and warrants orthopaedic referral. Arrange a hip ultrasound using the Graf method, typically around six weeks; a clearly unstable hip at birth is referred earlier. Breech presentation and a positive family history are key risk factors that trigger hip ultrasound regardless of a normal examination. Confirmed DDH is managed in a Pavlik harness in the first months. [5]

3. The dimple is within the gluteal cleft, under 5 mm deep, and has no other stigmata — a simple dimple, which is benign and needs no imaging. Imaging (ultrasound, then MRI if abnormal) and neurosurgical referral are reserved for high-risk stigmata: a dimple above the cleft, a hair tuft, lipoma, haemangioma, or a deviated gluteal fold. [15] [16]