O&G · Neonatal care — hypoxic-ischaemic encephalopathy
Neonatal encephalopathy, HIE and therapeutic hypothermia
Also known as Neonatal encephalopathy · Hypoxic-ischaemic encephalopathy · HIE · Birth asphyxia (avoid) · Perinatal asphyxia · Therapeutic hypothermia
Exam-exhaustive FRANZCOG fellowship reference on neonatal encephalopathy and HIE — Sarnat staging reproduced accurately, the ACOG/AAP 2014 acute-intrapartum framework and cord-gas criteria (pH under 7.0, base deficit 12 mmol/L or worse), the ANZ three-gate cooling criteria and the 6-hour window, the RCT and RR evidence (CoolCap, NICHD, TOBY, ICE, optimal-cooling, HELIX, the mild-HIE pilot and the 33-to-35 week preterm trial), the differential of the encephalopathic newborn, and the medico-legal significance of the language you write. ANZ-primary, globally tagged to MRCOG and ABOG.
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Target exams
Red flags
- Apgar under 5 at 10 minutes, ongoing resuscitation at 10 minutes, or cord pH under 7.0 or base deficit 12 mmol/L or worse — meet Gate 1, call the cooling centre, start the 6-hour clock
- Warming the depressed baby under a radiant heater is the killer pitfall — hyperthermia worsens brain injury; once cooling is contemplated, the radiant warmer goes off
- An encephalopathy that declares itself late, with no hourly Sarnat scoring, is how the 6-hour window is missed — assess at least hourly for the first 6 hours
- Writing 'birth asphyxia' or 'fetal distress' in the notes is indefensible in court — write what you observed, when you observed it, and what you did
- Normal cord gases, no sentinel event, a Category I trace throughout — pivot the differential; do not force an HIE diagnosis
- Cooling in a low-resource setting without intensive care support increased mortality in HELIX — it is not a global standard
The CTG came up Category III at the start of the second stage. You delivered by Category 1 caesarean in nine minutes. At 10 minutes the baby is still being ventilated, the cord gas is pH 6.95, and the team is asking you what happened. The next six hours decide whether this child has cerebral palsy. You are the obstetrician in the cooling decision, in the documentation, and in the medico-legal record — and the words you write tonight will be read aloud in court in five years.[2]
Overview and definition
Neonatal encephalopathy (NE) is a clinical syndrome: disturbed neurological function in the term or near-term infant during the first hours and days of life — altered consciousness, abnormal tone and reflexes, autonomic dysfunction, and often seizures. Hypoxic-ischaemic encephalopathy (HIE) is the aetiological subset of NE caused by a perinatal hypoxic-ischaemic insult, and it is the subset cooling was built for.[1][2]
Three rules follow from those two sentences and the examiner is testing all three:[2]
- NE is a syndrome; HIE is a cause. The first question is always "is this NE?" and the second is "is it HIE?" Confusing the two is the most common station error and the most dangerous one to commit to paper.
- The 2014 ACOG/AAP report was renamed Neonatal Encephalopathy and Neurologic Outcome precisely to drive that distinction. A minority of term cerebral palsy is attributable to an acute intrapartum event — write and counsel accordingly.[2]
- "Birth asphyxia" and "fetal distress" are indefensible terms. They imply a mechanism you have not proven. Write what you observed, when you observed it, and what you did.[2]
The 35-week gestational floor exists because the cooling trials recruited at or above this gestation; below it, the germinal matrix is still fragile and the evidence base changes (see the Faix trial below).[12]
References12ShowHide
- [1]Sarnat HB, Sarnat MS Neonatal encephalopathy following fetal distress. A clinical and electroencephalographic study Arch Neurol, 1976.PMID 987769
- [2]American College of Obstetricians and Gynecologists' Task Force on Neonatal Encephalopathy Executive summary: Neonatal encephalopathy and neurologic outcome, second edition. Report of the American College of Obstetricians and Gynecologists' Task Force on Neonatal Encephalopathy Obstet Gynecol, 2014.PMID 24785633
- [3]Gluckman PD, Wyatt JS, Azzopardi D, et al. Selective head cooling with mild systemic hypothermia after neonatal encephalopathy: multicentre randomised trial Lancet, 2005.PMID 15721471
- [4]Shankaran S, Laptook AR, Ehrenkranz RA, et al. Whole-body hypothermia for neonates with hypoxic-ischemic encephalopathy N Engl J Med, 2005.PMID 16221780
- [5]Azzopardi DV, Strohm B, Edwards AD, et al. Moderate hypothermia to treat perinatal asphyxial encephalopathy N Engl J Med, 2009.PMID 19797281
- [6]Jacobs SE, Morley CJ, Inder TE, et al. Whole-body hypothermia for term and near-term newborns with hypoxic-ischemic encephalopathy: a randomized controlled trial Arch Pediatr Adolesc Med, 2011.PMID 21464374
- [7]Shankaran S, Laptook AR, Pappas A, et al. Effect of depth and duration of cooling on deaths in the NICU among neonates with hypoxic ischemic encephalopathy: a randomized clinical trial JAMA, 2014.PMID 25536254
- [8]Azzopardi D, Strohm B, Marlow N, et al. Effects of hypothermia for perinatal asphyxia on childhood outcomes N Engl J Med, 2014.PMID 25006720
- [9]Jacobs SE, Berg M, Hunt R, Tarnow-Mordi WO, Inder TE Cooling for newborns with hypoxic ischaemic encephalopathy Cochrane Database Syst Rev, 2013.PMID 23440789
- [10]Thayyil S, Pant S, Montaldo P, et al. Hypothermia for moderate or severe neonatal encephalopathy in low-income and middle-income countries (HELIX): a randomised controlled trial in India, Sri Lanka, and Bangladesh Lancet Glob Health, 2021.PMID 34358491
- [11]Montaldo P, Cirillo M, Burgod C, et al. Whole-Body Hypothermia vs Targeted Normothermia for Neonates With Mild Encephalopathy: A Multicenter Pilot Randomized Clinical Trial JAMA Netw Open, 2024.PMID 38709535
- [12]Faix RG, Laptook AR, Shankaran S, et al. Whole-Body Hypothermia for Neonatal Encephalopathy in Preterm Infants 33 to 35 Weeks' Gestation: A Randomized Clinical Trial JAMA Pediatr, 2025.PMID 39992674