What Is the Sarnat Staging Score?

When a baby shows signs of brain injury after a difficult birth, one of the first questions doctors try to answer is: how severe is it? The Sarnat staging score is the clinical tool most often used to answer that question. It helps neonatal teams grade the severity of hypoxic-ischemic encephalopathy (HIE), a brain injury caused by a lack of oxygen and blood flow around the time of delivery, and decide what treatment a newborn needs.

Sarnat staging also matters well beyond the delivery room. The score that a baby receives in the hours after birth often becomes a key piece of evidence in birth injury and medical malpractice cases involving HIE, cerebral palsy, and other long-term outcomes.

Where the Sarnat Score Comes From

The score was first published in 1976 by Drs. Harvey B. Sarnat and Margaret S. Sarnat. Their original study looked at 21 newborns who had experienced fetal distress, and described a structured way to grade the sequential changes in clinical signs and electroencephalogram (EEG) findings that followed.

The original purpose was to give clinicians a consistent way to describe how a newborn’s neurological condition was evolving and to help predict outcomes. Almost five decades later, the Sarnat score is one of the most widely used bedside tools for assessing newborns with suspected HIE, and a modified version is now part of the standard criteria used to identify babies who may benefit from therapeutic hypothermia (cooling) treatment.

The Three Stages of HIE

Sarnat staging classifies neonatal encephalopathy into three stages of increasing severity. The categories are based on a structured neurological examination of the baby, usually performed within the first six hours of life and repeated as the clinical picture develops.

Stage 1: Mild

Babies in Stage 1 are typically hyperalert, may show exaggerated reflexes, and have increased sympathetic responses such as a fast heart rate or dilated pupils. Muscle tone is generally normal, seizures are not usually present, and the EEG is typically normal. Stage 1 features often resolve within the first 24 hours after birth, and most babies who do not progress beyond this stage have favourable neurodevelopmental outcomes.

Stage 2: Moderate

Babies in Stage 2 are lethargic or obtunded — less responsive than expected — and may show low muscle tone (hypotonia), abnormal reflexes, and a flexed posture. Seizures are common in this stage. Autonomic signs tend to shift to a parasympathetic pattern, with a slower heart rate, smaller pupils, and increased secretions. The EEG is often abnormal. Stage 2 can last for several days. Outcomes vary depending on how long the moderate stage persists, the response to treatment, and the imaging findings that follow.

Stage 3: Severe

Babies in Stage 3 are stuporous or comatose, with very low (flaccid) muscle tone, suppressed or absent brainstem reflexes, and depressed autonomic function. The EEG can be severely abnormal, including periodic, low-voltage, or isoelectric tracings. Severe HIE carries a high risk of death and a high risk of significant long-term neurological impairment among survivors, including cerebral palsy, seizure disorders, and cognitive disability.

What the Examination Looks At

The Modified Sarnat exam in common use today evaluates six categories. A trained examiner looks at each category and scores it as normal, mild, moderate, or severe:

• Level of consciousness: is the baby alert, hyperalert, lethargic, or comatose?
• Spontaneous activity: what kind of movements is the baby making on their own?
• Posture: distal flexion, full extension, decerebrate posturing, and so on.
• Tone: overall muscle tone, ranging from normal to hypertonic, hypotonic, or flaccid.
• Primitive reflexes: including the suck reflex and the Moro (startle) reflex.
• Autonomic system: pupils, heart rate, and breathing pattern.

The pattern of findings across these six categories is what determines the overall stage. Many neonatal teams also incorporate EEG findings, which were part of the original Sarnat description, alongside the bedside exam.

Why the Score Matters Clinically

The Sarnat score is more than a description. It directly affects treatment. Babies who meet criteria for moderate or severe encephalopathy in the first six hours of life are generally considered candidates for therapeutic hypothermia, a treatment in which the baby’s body temperature is carefully lowered for 72 hours to reduce ongoing brain injury. Therapeutic hypothermia is the standard of care in eligible newborns and has been shown to improve outcomes in moderate to severe HIE.

Because the window for starting cooling is narrow, usually within six hours of birth, accurate and timely Sarnat scoring is essential. Missing or delaying the assessment, or misclassifying the severity, can mean a baby does not receive treatment they should have received.

Why the Score Matters in Birth Injury Cases

In a medical malpractice claim involving a birth injury, the Sarnat score becomes one of several pieces of evidence used to understand what happened to the baby and when. Lawyers and qualified medical reviewers will typically look at the hospital chart for:

• The Sarnat stage documented in the first hours after birth
• How that stage changed over time
• Whether therapeutic hypothermia was offered, and if so, how quickly
• How the clinical findings line up with cord blood gases, Apgar scores, and imaging such as MRI
• Whether there is a clear pattern consistent with an injury occurring during labour and delivery

Together, these findings help establish two key questions: how badly the baby was injured, and whether the events around the birth fell below the standard of care reasonably expected of the medical team.

Limitations of the Sarnat Score

The Sarnat score is widely used because it is structured, easy to apply at the bedside, and well known to neonatal teams. It also has limits worth understanding:

• It is a snapshot in time. A single Sarnat score does not capture how the baby’s condition is changing, which is why repeat assessments matter.
• It does not by itself identify the cause of the encephalopathy; HIE is one of several possible causes.
• Scoring depends on the examiner’s training and experience, which is why standardized teaching and documentation are emphasized in neonatal units.
• The original study was small and based on only 21 babies, so prognostic statements based on Sarnat staging alone need to be interpreted in context with imaging, EEG, and follow-up.

These limitations are part of why MRI findings, EEG, cord gases, and long-term developmental assessments are all considered alongside the Sarnat score when evaluating a child’s condition and prognosis.

If You Are Concerned About a Birth Injury

Parents who learn that their child was assessed with moderate or severe HIE often have a long road of medical follow-up ahead, including ongoing assessments for cerebral palsy, developmental delay, seizures, and other conditions. The records from those first hours and days after birth, including the Sarnat scores, can be central both to medical care and to understanding whether anything could or should have been done differently.

The team of lawyers at Diamond and Diamond has experience handling birth injury and HIE-related medical malpractice claims across Ontario, Alberta, Saskatchewan, and beyond. We can help you obtain and review the relevant medical records, work with qualified medical reviewers, and explain your options.

To speak with someone now, call our 24/7 injury hotline at 1-800-567-HURT or visit diamondlaw.ca. We offer free consultations and case evaluations to families across Canada.