Newborn · HIE Assessment
Sarnat HIE Staging
Clinical staging of newborn hypoxic-ischaemic encephalopathy (HIE): Sarnat 1 (mild, usually recovers), 2 (moderate, cooling indication), 3 (severe, cooling indication, worst prognosis). NICE / TOBY trial.
Last reviewed 2 June 2026
Sarnat staging — neonatal HIE
Hypoxic-ischaemic encephalopathy stage I / II / III
Score all 7 domains to determine the Sarnat stage.
Educational tool only — not medical advice. Sarnat staging is performed by trained neonatologists. Stage II / III determination is THE eligibility criterion for therapeutic hypothermia, which must be initiated within 6 hours of birth. See the Therapeutic Hypothermia eligibility checker.
What does this mean?
Sarnat staging (1976) grades neonatal hypoxic-ischaemic encephalopathy by examination — a global synthesis of consciousness, tone, posture, primitive reflexes, autonomic function, and seizure activity. Stage I (mild) typically resolves with normal outcome. Stage II (moderate) and Stage III (severe) are the trigger for therapeutic hypothermia in babies ≥ 36 wk and ≤ 6 h of life — cooling to 33.5 °C for 72 h via whole-body or selective head cooling. The original NICHD, CoolCap, and TOBY trials showed cooling reduces death or major disability by ~25 % (NNT ~7). The Sarnat exam should be repeated at intervals because the picture evolves over the first 24–48 h. Adjuncts: aEEG, MRI brain on day 5–7, neurology and family-meetings throughout. Long-term follow-up to school-age is standard given the high neurodevelopmental risk.
What is HIE?
Hypoxic-ischaemic encephalopathy — brain dysfunction from inadequate oxygen + blood flow around birth. ~1-3 per 1000 live births in developed countries.
Sarnat staging
- Sarnat 1 (mild): hyperalert, irritable, mildly increased tone, no seizures. Usually full recovery.
- Sarnat 2 (moderate): lethargy, hypotonia, suppressed reflexes, possible seizures. Cooling indication.
- Sarnat 3 (severe): coma, flaccid, absent reflexes, frequent seizures, brainstem dysfunction. Cooling indication. Worst prognosis.
How HIE is diagnosed
- Birth history (sentinel event, low APGAR, resuscitation, severe acidosis).
- Neurological exam (Sarnat).
- Lactate, blood gas.
- Cranial ultrasound + MRI.
- Continuous EEG / aEEG.
Why 6-hour window?
Cooling started within 6 hours of birth most effective for neuroprotection. Sarnat assessed 1-2h + 4-6h; staging can change.
Prognosis by stage
- Sarnat 1: 98% normal outcomes.
- Sarnat 2 with cooling: ~50-60% normal/mild; ~10-15% mild-moderate disability; ~25-35% severe disability or death.
- Sarnat 3 with cooling: high mortality + significant disability in survivors.
MRI in first week refines prognosis.
Treatment
- NRP/NLS at birth.
- NICU stabilisation.
- Therapeutic cooling 33-34°C for 72h (Sarnat 2-3).
- Seizure management.
- BP / volume / glucose support.
- Avoid hyperthermia.
- Gradual nutrition.
Seizures
Common (~50-65% moderate-severe). Phenobarbital first-line. Continuous EEG monitoring. Resolve in most after acute phase. Postnatal epilepsy risk ~10-30% by 5 years.
MRI patterns
- BGT (basal ganglia / thalamus): severe motor disability; athetoid CP.
- Watershed: cognitive impairment more than motor.
- Global: worst; severe disability.
- Mild focal: best prognosis.
Follow-up
- MRI first week.
- BERA hearing test.
- Visual assessment.
- Neurology review.
- Developmental follow-up 3, 6, 12, 24 months + more.
- Physiotherapy / OT / SALT.
- Paediatric community follow-up.
Breastfeeding
Express breast milk from birth (within 6 hours). NG/IV nutrition during cooling. Gradual oral feeds after stability + rewarming.
Different scenarios
Scenario 1: Cord prolapse, APGAR 3 at 5 min, Sarnat 2
Cooling started within 6h. NICU 5-7 days. MRI day 7. Follow-up plan.
Scenario 2: Sarnat 1, hyperalert + jittery, no seizures
Observation. Most recover fully. Routine follow-up.
Scenario 3: Sarnat 3, multiple seizures, MRI shows BGT injury
Counselling about prognosis. Cooling completed. Early intervention. CP likely. Long-term support.
Scenario 4: Late-preterm 35 wk, mild HIE
Cooling indications less clear; some centres cool. Specialist team decision.
Scenario 5: Recovered from cooling, normal MRI, discharged
Excellent prognosis. Routine follow-up to age 2 + occasionally further.
Care guidance — HIE / Sarnat
- 6-hour window for cooling.
- Sarnat 2-3 indicates cooling.
- EEG monitoring for seizures.
- MRI within first week.
- Express breast milk from birth.
- BLISS UK support.
- Birth trauma + mental health support.
- Long-term developmental follow-up.
Sources
- Sarnat HB, Sarnat MS. Neonatal encephalopathy following fetal distress: a clinical and electroencephalographic study. Arch Neurol 1976.
- Azzopardi DV, et al. TOBY trial: hypothermia for HIE. NEJM 2009.
- NICE IPG347. Therapeutic hypothermia for HIE.
- BAPM. Therapeutic hypothermia framework.
- BLISS UK. bliss.org.uk.
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Frequently asked questions
What is HIE?
HYPOXIC-ISCHAEMIC ENCEPHALOPATHY — brain dysfunction from inadequate oxygen + blood flow around birth. AFFECTS ~1-3 PER 1000 LIVE BIRTHS in developed countries; higher globally. CAUSES: placental abruption, cord prolapse, uterine rupture, shoulder dystocia, severe maternal hypotension, severe pre-eclampsia, maternal sepsis. CONSEQUENCES range from full recovery to severe disability or death. SEVERITY GRADED with SARNAT staging (mild / moderate / severe). MODERATE-SEVERE eligible for therapeutic cooling treatment.
What's the Sarnat staging?
Clinical CLASSIFICATION of HIE severity. SARNAT 1 (MILD): hyperalert, irritable, mildly increased tone, possible jitteriness, NO seizures, brainstem normal. Usually full recovery. SARNAT 2 (MODERATE): lethargy/obtundation, hypotonia (low tone), suppressed reflexes, possible seizures, decreased spontaneous movement, autonomic dysfunction. INDICATION FOR COOLING. SARNAT 3 (SEVERE): coma, flaccid (no tone), absent reflexes, frequent seizures, brainstem dysfunction (no pupillary, gag), absent spontaneous movement, abnormal autonomic. INDICATION FOR COOLING; highest mortality / morbidity.
How is HIE diagnosed?
(1) BIRTH HISTORY — significant sentinel event (cord prolapse, abruption); LOW APGAR (especially at 10 min); needed resuscitation; severe acidosis (cord pH <7.0 or base deficit ≥12). (2) NEUROLOGICAL exam — Sarnat staging within first 6 hours. (3) BIOMARKERS — lactate, blood gas. (4) NEUROIMAGING — cranial ultrasound (bedside), MRI within first week (gold standard). (5) EEG / aEEG (amplitude-integrated EEG) — continuous monitoring; predicts outcome. SHARED clinical picture diagnoses.
Why is Sarnat done in first 6 hours?
TIME-CRITICAL window for THERAPEUTIC COOLING decision. EVIDENCE: cooling started within 6 hours of birth most effective for neuroprotection. SARNAT done at: 1-2 hours, 4-6 hours. STAGING can change — repeat exam matters. ALSO INFORMS: predicts initial severity + response to treatment. EARLIER intervention = better outcomes.
What's the prognosis?
DEPENDS on severity + treatment. SARNAT 1 (mild): 98% normal outcomes. SARNAT 2 (moderate): with cooling — ~50-60% normal/mild impairment; ~10-15% mild-moderate disability; ~25-35% severe disability or death. SARNAT 3 (severe): worst prognosis even with cooling — high mortality + significant disability in survivors. MRI in first week + EEG patterns refine prognosis. EARLY INTERVENTION (physio, OT, SALT) improves outcomes.
What's the treatment?
(1) NEONATAL RESUSCITATION at birth following NRP/NLS; (2) NICU admission for stabilisation; (3) THERAPEUTIC HYPOTHERMIA (cooling) — 33-34°C for 72 hours then rewarming. For Sarnat 2-3, started within 6 hours, term + late preterm ≥36 weeks; (4) SEIZURE management (phenobarbital first-line; phenytoin, levetiracetam if not controlled); (5) BLOOD PRESSURE / volume support; (6) GLUCOSE control; (7) AVOID hyperthermia (worsens injury); (8) NUTRITION (IV initially, gradual enteral when stable). /calculators/neonatal-cooling for cooling detail.
Will my baby have seizures?
COMMON in HIE (~50-65% of moderate-severe). MONITORED with continuous EEG / aEEG. TREATMENT: PHENOBARBITAL first-line; phenytoin, levetiracetam if not controlled. SEIZURES during cooling: concerning + predict worse outcome. RESOLVE in most after acute phase. POSTNATAL EPILEPSY risk: ~10-30% develop epilepsy by 5 years (HIE-related). ANTIEPILEPTIC continued until seizure-free; reviewed regularly.
What happens during cooling?
BABY in NICU on COOLING MAT / blanket / cap. RECTAL TEMPERATURE 33-34°C continuously monitored. SEDATION (morphine) to prevent shivering. VENTILATOR support if needed. EEG monitoring. 72 HOURS then SLOW REWARM over 12 hours. PARENTS at bedside; limited holding during cooling but talking, reading, music encouraged. SUPPORT services (chaplain, BLISS, mental health).
Can I hold my baby?
VERY LIMITED during cooling. Multiple monitors + cooling system + possibly ventilator. Gentle touch through portholes. Voice + presence beneficial. AFTER REWARMING: gradual return to normal handling; kangaroo care encouraged once stable. EMOTIONAL impact significant — counselling support.
What investigations after cooling?
(1) MRI BRAIN — within first week; specific patterns predict outcomes; (2) FORMAL HEARING test (BERA — bone-conducted auditory brainstem response); HIE associated with hearing loss; (3) VISUAL assessment; (4) NEUROLOGY review pre-discharge; (5) DEVELOPMENTAL follow-up scheduled 3, 6, 12, 24 months + further if concerns; (6) PHYSIOTHERAPY / OT / SALT involvement; (7) PAEDIATRICIAN community follow-up. STRUCTURED neuroprotective programme.
What does MRI show?
BRAIN INJURY PATTERNS predict outcomes: (1) BASAL GANGLIA / THALAMUS (BGT) — most concerning; severe motor disability common (athetoid cerebral palsy); (2) WATERSHED (peri-Rolandic, parasagittal) — milder; cognitive impairment more than motor; (3) GLOBAL injury — worst; severe disability; (4) MILD focal — best prognosis. MRI in first 4-10 days most informative. SHARED with parents + neurology + paediatrics for prognosis discussions.
Will my baby have cerebral palsy?
POSSIBLY — depends on severity + injury location. Sarnat 1: very low CP risk. Sarnat 2 with cooling: ~10-15% CP. Sarnat 3 with cooling: ~30-50%. MRI patterns refine prediction. EARLY signs may not appear until weeks-months: persistent abnormal tone, delayed milestones, asymmetric movements. EARLY INTERVENTION (physio from neonatal period) improves function. CP DOES NOT mean inability to live well — varies from mild to severe.
Can I breastfeed?
DURING COOLING: baby usually too unwell to feed orally; NG/IV nutrition. EXPRESS BREAST MILK from birth (within 6 hours ideally) — hospital pump every 2-3h. STORE in fridge/freezer. AFTER COOLING + STABILITY: gradual oral feed introduction; breastfeeding possible. LACTATION CONSULTANT support; community midwife. EXPRESSING protects milk supply.
Was this preventable?
USUALLY NO. HIE causes (placental abruption, cord prolapse, etc.) often UNFORESEEABLE. PREVENTION ATTEMPTS: routine antenatal care; vigilance for risk factors; appropriate intrapartum monitoring; prompt response to fetal distress; experienced birth attendance. NOT YOUR FAULT. SOMETIMES delivery decisions / timing matter — but outcomes assessment with hindsight unfair. BIRTH TRAUMA support important; legal advice if questions about care quality.
How does this relate to other calculators on BumpBites?
Companion: /calculators/neonatal-cooling; /calculators/thompson-hie alternative score; /calculators/apgar-score; /calculators/nrp-algorithm; /calculators/silverman-andersen; /calculators/eos-sepsis; /calculators/magnesium-sulphate (neuroprotection in pregnancy).