Late-preterm infant: risks and corrected-age follow-up — viva

Stem

Examiner-led viva on the late-preterm infant. [1]

Examiner: This 35-week infant looks well. Why should I be more worried than about a full-term baby? [1] [3]

Strong answer: Because late-preterm infants (34+0 to 36+6) look mature but carry neonatal mortality around three times and readmission two to three times that of full-term infants, driven by multi-organ immaturity — surfactant near-maturity that still permits RDS and TTN, immature bilirubin conjugation, an uncoordinated suck-swallow-breathe pattern, fragile thermoregulation and limited glycogen stores. The "almost term" appearance is the trap; the behaviour is preterm. [1] [3]

Examiner: The parents want to go home today. What must be true before you discharge this infant? [9]

Strong answer: I discharge against an explicit gate, never by weight or age alone. All five must be met: thermal stability in an open cot (axillary 36.5 to 37.5 degrees Celsius), feeding competence with sustained weight gain, glucose stability off supplements, no significant apnoea for five to seven days, and bilirubin well below threshold and falling — plus family readiness and a follow-up booked within 48 to 72 hours. This infant currently fails temperature, feeding and bilirubin, so discharge today is unsafe. [9]

Examiner: His bilirubin is approaching the phototherapy threshold. How do you decide, and why is the threshold different from a term infant's? [8]

Strong answer: I plot the total serum bilirubin on a gestational-age- and age-specific nomogram and treat at the 35-week threshold, which is lower than the term threshold because late-preterm infants have immature glucuronyl transferase, lower albumin binding and a less mature blood-brain barrier, so the same value carries more risk of bilirubin encephalopathy. I phototherapy if at threshold and recheck to confirm a falling trend. [8]

Examiner: Suppose this mother had presented in labour at 35 weeks without prior steroids. What would you have offered antenatally, and on what evidence? [6]

Strong answer: A single course of betamethasone, given late preterm delivery was anticipated within seven days and no prior course had been given. The ALPS trial (Gyamfi-Bannerman 2016, NEJM) demonstrated reduced respiratory distress syndrome, transient tachypnoea of the newborn and need for respiratory support in the 34 to 36+6-week band. [6]

Examiner: He goes home well. How will you follow him up, and for how long? [7]

Strong answer: I follow in corrected age — chronological age minus the five weeks born early — with the first review within 48 to 72 hours, then at two weeks, four months, eight to twelve months, eighteen to twenty-four months and four to five years. I plot growth on Fenton charts to 50 weeks postmenstrual age then transition to WHO or INTERGROWTH-21st standards, and continue correcting milestones until at least two years, keeping a low threshold to assess cognition and behaviour through to school age because the long-term signal often emerges late. [7]

Examiner: Name the cardinal error you would guard against. [4]

Strong answer: Discharging before the gate is met — by weight, gestational age or parental pressure. That is the leading cause of the two-to-three-fold readmission excess in this group, with jaundice, dehydration and feeding failure dominating. [4] [1]