Neonatology: Summative Revision

Physiological jaundice appears after 24 hours, peaks at days 3–4 (term) or days 5–7 (preterm), and resolves by day 10 (term) or day 14 (preterm). Pathological jaundice: appears within 24 hours, rises >5 mg/dL/day, TSB exceeds phototherapy threshold, conjugated fraction >20% of total, or persists beyond 14 days (term) / 21 days (preterm).

Thresholds are gestational-age and risk-stratified — always use the nomogram, not a fixed number. For a low-risk term neonate (≥38 weeks): phototherapy at approximately 15–18 mg/dL at 72 hours; exchange transfusion approximately 5 mg/dL higher. Risk factors lowering the threshold: isoimmune haemolytic disease, G6PD deficiency, asphyxia, sepsis, prematurity.

ABO incompatibility: O-mother / A or B baby; no prior sensitisation needed; spherocytes on film; weakly positive DCT; usually mild. Rh disease (anti-D): requires prior sensitisation; strongly positive DCT; can cause hydrops; prevented by anti-D prophylaxis. G6PD deficiency: X-linked; triggers: infections, drugs (dapsone, primaquine), fava beans; bite cells and Heinz bodies on film.

Jaundice <24 h = always pathological Conjugated >20% = investigate IVIG: only for confirmed isoimmune haemolysis G6PD: avoid triggers lifelong

RDS: antenatal corticosteroids (betamethasone ≥24 h before delivery) are the most effective preventive measure. Incidence inversely proportional to gestational age. TTN: elective LSCS without labour bypasses the catecholamine-driven fluid clearance mechanism — classic setup. MAS + PPHN: right-to-left ductal shunt on echo is the hallmark; treat with iNO. IDM and RDS: fetal hyperinsulinaemia antagonises cortisol-driven surfactant synthesis — do not use gestational age alone to exclude RDS in an IDM.

Tension PTX: needle 2nd ICS MCL immediately Transillumination = rapid bedside test Surfactant: intratracheal, not IV

Listeria monocytogenes is intrinsically resistant to ALL cephalosporins — this is why benzylpenicillin (not cefotaxime) is used for EOS; ampicillin + gentamicin is the regimen of choice when Listeria is confirmed. CoNS LOS: vancomycin + remove central line; source control is non-negotiable. Invasive candidiasis: fluconazole first-line for susceptible C. albicans; remove central line; ophthalmology + echo to exclude end-organ disease.

Mandatory in all confirmed or probable sepsis (unless haemodynamically unstable). Meningitis occurs in up to 30% of bacteraemic neonates. Do LP before antibiotics if possible — CSF sterilises within hours. Meningitis extends treatment to 14–21 days and may require adding a third-generation cephalosporin.

Culture before Abx — never delay Abx for culture Listeria: cephalosporins FAIL Candida: never a contaminant in VLBW

Criteria: ≥36 weeks gestation + perinatal asphyxia (cord pH ≤7.0 or BD ≥16 mmol/L, or need for resuscitation) + clinical/aEEG evidence of encephalopathy (Grade II or III). Target: 33–34°C for exactly 72 hours; must start within 6 hours of birth. NNT ~7 to prevent one death or major neurodisability. Seizures are not a contraindication.

Chest compressions when HR <60/min after 30 seconds of effective PPV. Compression:ventilation ratio 3:1 (not 15:2). Adrenaline (IV umbilical vein preferred) when HR <60/min after 60 seconds of coordinated CPR. Phenobarbitone 20 mg/kg IV is first-line for neonatal seizures; clearance reduced ~20–30% during cooling — monitor levels carefully.

DWI (diffusion-weighted imaging): most sensitive in first 7 days, peaks at 3–5 days. T1/T2: most informative at 7–14 days. PLIC (posterior limb of internal capsule) signal at 7–14 days predicts motor outcome. Basal ganglia + thalamic injury → dyskinetic CP; watershed cortical injury → spastic quadriplegia.

TH window: 6 hours TH duration: exactly 72 hours MRI at 5–7 days for prognosis

Subtle: lip-smacking, cycling, eye deviation, apnoea — commonest in term neonates; some have no EEG correlate. Focal clonic: rhythmic jerking one limb; not suppressible (distinguishes from jitteriness); EEG correlate present. Tonic: sustained posturing. Jitteriness: stimulus-sensitive, suppressible by restraint, no eye deviation, no EEG correlate — not a seizure.

Late hypocalcaemia (day 5–14): cow’s milk formula → high phosphate load → hyperphosphataemia → hypocalcaemia. Pattern: low Ca + high PO₄ + normal Mg. Treat with calcium gluconate. HSV encephalitis: onset day 7–14; lymphocytic CSF pleocytosis; 30–40% occur without skin vesicles; aciclovir 20 mg/kg 8-hourly for 21 days. Pyridoxine dependency (ALDH7A1 mutation): refractory seizures from birth; normal metabolic screen; dramatic response to IV pyridoxine 100 mg; lifelong oral pyridoxine.

Phenobarbitone 20 mg/kg IV = first-line HSV: aciclovir before PCR result Pyridoxine trial in refractory unexplained seizures

Ductus kept patent by PGE2; fails to close in preterm due to high circulating PGE2 and reduced smooth muscle responsiveness. Haemodynamically significant PDA: bounding pulses, wide pulse pressure, continuous murmur, left atrial dilatation on echo. Treatment: fluid restriction + diuretics → indomethacin or ibuprofen (COX inhibitor, ↓ PGE2); oral paracetamol emerging alternative; surgical ligation for pharmacological failure.

Threshold for intervention: <2.6 mmol/L in at-risk neonates. At <1.5 mmol/L or symptomatic: IV 10% dextrose 2 mL/kg bolus + maintenance infusion (GIR 4–6 mg/kg/min). Dextrose gel for mild asymptomatic cases in term/near-term only. SGA: limited glycogen + impaired gluconeogenesis + relative hyperinsulinism.

Pneumatosis = pathognomonic of NEC Breast milk reduces NEC risk 6-fold ROP screen: 4 wk of life or 31 wk CGA, whichever later

NAIT: HPA-1a antibodies (mother lacks HPA-1a antigen); first pregnancy affected; mother’s platelets normal; treat with HPA-1a-negative irradiated platelets or IVIG. Polycythaemia: venous Hct >65%; partial exchange transfusion with normal saline (not albumin) for symptomatic or Hct >70%. HDN / ABO: spherocytes, weak DCT, first pregnancy possible; IVIG for confirmed isoimmune haemolysis.

Commonest preventable cause of intellectual disability. TSH-based newborn screening. Start levothyroxine 10–15 mcg/kg/day within 2 weeks of life. Delay beyond 2 weeks causes irreversible neurodevelopmental damage even if treated adequately later. Commonest cause: thyroid dysgenesis. Do not defer for scintigraphy — treat first.

Opioid withdrawal: onset 24–72 h (methadone), 12–24 h (heroin). Finnegan score ≥8 on two assessments triggers treatment. First-line: oral morphine solution titrated to Finnegan score, then weaned 10%/1–2 days. Clonidine/phenobarbitone: adjuncts only. Naloxone: absolutely contraindicated — precipitates acute severe withdrawal and seizures.

Unfortified breast milk does not meet preterm demands for protein (3.5–4 g/kg/day), calcium, and phosphorus — add human milk fortifier (HMF). Breast milk still preferred: reduces NEC 6-fold, provides immune protection (sIgA, lactoferrin), improves neurodevelopment. Donor pasteurised breast milk (milk bank) if maternal EBM unavailable.

CMV: periventricular calcification Rubella: cataracts + cardiac + SNHL Toxo: diffuse calcification + chorioretinitis Naloxone: NEVER in opioid-exposed neonate CH: treat within 2 weeks, not after scintigraphy Syphilis: aqueous penicillin IV, not IM benzathine