How to Interpret the Thompson Score for HIE Severity Assessment

Quick take: The Thompson score is a quick bedside tool doctors use to assess how severe hypoxic-ischemic encephalopathy (HIE) — a type of brain injury caused by lack of oxygen — is in a newborn. It ranges from 0 to 22, with higher scores meaning more severe injury. While it’s not a crystal ball, it helps guide treatment decisions like cooling therapy. This article explains how the score is calculated, what the numbers mean, and when to trust (or question) the results.

It’s 3 a.m., and the NICU is quiet except for the beep of monitors. Your baby was born just hours ago, and now the words “HIE” and “Thompson score” are swirling in your head. The neonatologist just said, “We’ll calculate the Thompson score to see how severe this might be.” You nod, but inside you’re thinking: What does that even mean? Is a 12 bad? Will my baby be okay?

If this moment feels familiar, you’re not alone. Many parents first hear about the Thompson score in the blur of a NICU admission, when every number and term feels like a clue — or a threat. The good news? The Thompson score is designed to be simple enough for doctors to use at the bedside, which means it’s also something you can understand. And understanding it can help you ask better questions, advocate for your baby, and feel a little less lost in the storm.

In this guide, we’ll break down exactly what the Thompson score is, how it’s calculated, what the numbers mean, and how it fits into your baby’s care. We’ll also cover what the score can’t tell you, and when to focus on the bigger picture instead of the number on the chart.

What is the Thompson score and why does it matter?

Hypoxic-ischemic encephalopathy (HIE) is a type of brain injury that happens when a baby’s brain doesn’t get enough oxygen or blood flow around the time of birth. It’s rare — affecting about 1 to 3 in every 1,000 live births in high-income countries — but it’s one of the most common causes of newborn brain injury. And because the brain is still developing, early treatment can make a big difference in long-term outcomes.

That’s where the Thompson score comes in. Developed in the 1990s by Dr. Malcolm Thompson and his team, it’s a simple scoring system that helps doctors quickly assess how severe a baby’s HIE might be. It’s not a diagnosis on its own — HIE is diagnosed based on a combination of clinical signs, lab tests, and sometimes brain imaging. But the Thompson score gives doctors a standardized way to communicate how serious the situation is, and it helps guide decisions about treatments like therapeutic hypothermia (cooling therapy), which can reduce brain damage if started within the first six hours after birth.

“Many parents ask me, ‘What does this number mean for my baby’s future?’” says a neonatologist who’s used the Thompson score for over a decade. “I tell them: it’s a snapshot, not a prophecy. It helps us decide what to do today, but it’s just one piece of the puzzle.”

How is the Thompson score calculated?

Here’s a breakdown of the six components:

Let’s walk through an example. Imagine a baby who is:

• Floppy (hypotonic) — 2 points
• Lethargic (hard to wake) — 2 points
• Having subtle seizures (lip-smacking) — 1 point
• Holding their hands in tight fists — 2 points
• Moro reflex is weak — 1 point
• Grasp reflex is weak — 1 point

This baby’s Thompson score would be 2 + 2 + 1 + 2 + 1 + 1 = 9.

Most doctors calculate the Thompson score within the first few hours after birth, and then again at 24 and 48 hours to track how the baby is doing. The score can change — and that’s a good thing. A baby whose score drops over time is usually showing signs of improvement.

If you’d like to try calculating a Thompson score yourself (for example, to understand a number you’ve seen in your baby’s chart), you can use our Thompson HIE Score calculator. It walks you through each component and gives you the total score instantly.

What do the Thompson score ranges mean?

The Thompson score is divided into three broad categories, each corresponding to a different level of HIE severity:

• 0–5: Mild HIE. Babies in this range usually have normal or near-normal muscle tone, reflexes, and alertness. They may be a little jittery or sleepy, but they don’t usually need cooling therapy. Most babies with mild HIE recover fully, though some may need extra support with feeding or breathing in the first few days.
• 6–14: Moderate HIE. This is the most common range for babies who are treated with therapeutic hypothermia (cooling therapy). Babies in this group often have low muscle tone, weak reflexes, and may be lethargic or have seizures. Cooling therapy can reduce the risk of long-term brain damage, and many babies in this range go on to have normal or near-normal development — though some may have mild delays or learning differences.
• 15–22: Severe HIE. Babies with scores in this range are very sick. They may be comatose, have frequent seizures, or show signs of brainstem dysfunction (like trouble breathing or regulating their heart rate). Cooling therapy is still offered, but the outlook is more guarded. Some babies with severe HIE have significant long-term disabilities, while others may not survive. Every baby is different, and outcomes depend on many factors beyond the Thompson score.

It’s important to remember that these ranges are guidelines, not rules. A baby with a score of 5 might still need cooling therapy if they have other concerning signs, while a baby with a score of 15 might do better than expected if they respond quickly to treatment. The Thompson score is a tool, not a crystal ball.

One mom, whose son had a Thompson score of 11, shared her experience: “The number felt like a life sentence at first. But the neonatologist told us, ‘This score helps us decide what to do today. It doesn’t tell us what your son will be like in a year.’ And she was right. He’s almost 3 now, and while he has some speech delays, he’s happy, curious, and full of personality. The score was just the starting point.”

How is the Thompson score used in clinical care?

The Thompson score isn’t just a number on a chart — it’s a key part of how doctors decide what to do next. Here’s how it’s typically used in the NICU:

1. Deciding whether to start cooling therapy

Therapeutic hypothermia (cooling therapy) is the only proven treatment for moderate to severe HIE. It involves cooling the baby’s body to about 33.5°C (92.3°F) for 72 hours, which slows down brain activity and reduces the risk of further damage. But cooling isn’t risk-free — it can cause side effects like low blood pressure or blood clotting problems — so doctors use the Thompson score (along with other factors) to decide who is most likely to benefit.

Current guidelines from the American Academy of Pediatrics (AAP) and the National Institute for Health and Care Excellence (NICE) recommend cooling therapy for babies with:

• A Thompson score of 6 or higher, or
• Signs of moderate to severe encephalopathy (like seizures or coma), even if the Thompson score is lower

2. Tracking progress over time

The Thompson score isn’t a one-time measurement. Doctors usually calculate it at least three times in the first 48 hours — at admission, at 24 hours, and at 48 hours. A baby whose score drops over time is usually improving, while a baby whose score stays the same or goes up may need more intensive treatment.

“We had a baby last week whose Thompson score went from 12 to 8 in 24 hours,” says a NICU nurse. “That drop told us the cooling therapy was working, and it gave the parents a lot of hope. Numbers aren’t everything, but when they move in the right direction, it’s a good sign.”

3. Helping parents understand what’s happening

The Thompson score can feel overwhelming for parents, but it can also be a way to start a conversation with the medical team. Instead of asking, “Is my baby okay?” (which is a big, unanswerable question), you might ask:

• “What was my baby’s Thompson score at admission, and how has it changed?”
• “What does this score mean for their treatment plan?”
• “What are the next steps if the score doesn’t improve?”

4. Guiding follow-up care

Babies who have had HIE — even mild HIE — usually need extra monitoring after they leave the NICU. The Thompson score can help doctors decide what kind of follow-up is needed. For example:

• Babies with mild HIE (scores 0–5) may need a hearing test and a developmental check-up at 6 months.
• Babies with moderate HIE (scores 6–14) often need regular visits with a developmental specialist, physical therapy, and early intervention services.
• Babies with severe HIE (scores 15–22) may need lifelong support, including physical therapy, occupational therapy, and special education services.

How accurate is the Thompson score?

The Thompson score is widely used because it’s simple, fast, and doesn’t require any special equipment. But like any tool, it has its limitations. Here’s what parents should know about its accuracy:

It’s good at predicting short-term outcomes

Studies show that the Thompson score is pretty good at predicting which babies will have complications in the first few days of life. For example, a 2018 study published in Pediatrics found that babies with Thompson scores of 15 or higher were much more likely to have seizures, trouble breathing, or feeding problems in the NICU.

It’s less reliable for long-term outcomes

While the Thompson score can give doctors a sense of how severe the HIE is right now, it’s not a perfect predictor of long-term outcomes like cerebral palsy, developmental delays, or learning disabilities. Some babies with high Thompson scores go on to have normal development, while others with lower scores may have challenges. Other factors — like how quickly treatment was started, whether the baby had seizures, and what brain imaging shows — play a big role in long-term prognosis.

It can miss mild HIE

The Thompson score is best at identifying moderate to severe HIE. Babies with mild HIE (scores 0–5) may have subtle signs that the Thompson score doesn’t capture well. That’s why doctors also look at other clues, like the baby’s Apgar scores, cord blood gases, and brain imaging (like an MRI or ultrasound).

It’s not the only tool

The Thompson score is one of several tools doctors use to assess HIE. Others include:

• Apgar score: A quick assessment of a baby’s health at 1 and 5 minutes after birth. Low Apgar scores (especially at 5 minutes) can be a sign of HIE, but they’re not specific — lots of things can cause a low Apgar score.
• Cord blood gases: Blood tests from the umbilical cord that show how much oxygen the baby was getting during birth. Low pH or high base deficit can be signs of HIE.
• Amplitude-integrated EEG (aEEG): A type of brain monitoring that shows electrical activity in the brain. It can help doctors spot seizures and assess how severe the HIE is.
• MRI: Brain imaging that can show areas of damage. An MRI is usually done after the first week of life, when the full extent of the injury is visible.

“The Thompson score is like a flashlight in a dark room,” says a neonatologist. “It helps us see what’s right in front of us, but we need other tools — like an EEG or an MRI — to see the whole picture.”

Thompson score vs. other HIE assessment tools

The Thompson score isn’t the only way to assess HIE severity. Here’s how it compares to two other common tools: the Sarnat staging system and the modified Sarnat score.

So which tool is best? It depends on the situation. The Thompson score is the most commonly used in NICUs because it’s simple and fast. The Sarnat staging is easier to remember but less detailed. The modified Sarnat score is more precise but takes longer to calculate, so it’s mostly used in research.

“In our NICU, we use the Thompson score for the initial assessment because it’s quick and reliable,” says a neonatologist. “But we also look at the baby’s Apgar scores, cord gases, and EEG to get a fuller picture. No single tool tells the whole story.”

Myth vs. fact

When it comes to the Thompson score, there’s a lot of confusion — and a few myths that just won’t quit. Let’s set the record straight.

Myth: A high Thompson score means your baby will have cerebral palsy or severe disabilities.

Fact: While a high Thompson score is a sign of more severe HIE, it doesn’t guarantee long-term disabilities. Many babies with moderate to severe HIE go on to have normal or near-normal development, especially if they receive cooling therapy quickly. Other factors — like whether the baby had seizures, what brain imaging shows, and how they respond to treatment — play a big role in outcomes. The Thompson score is a snapshot, not a prediction.

Myth: The Thompson score is the only thing doctors use to decide on cooling therapy.

Fact: The Thompson score is an important tool, but it’s not the only one. Doctors also look at the baby’s Apgar scores, cord blood gases, EEG results, and clinical signs like seizures or coma. Cooling therapy is usually recommended for babies with a Thompson score of 6 or higher or other signs of moderate to severe encephalopathy.

Myth: If your baby’s Thompson score is low, you don’t need to worry about HIE.

Fact: The Thompson score is best at identifying moderate to severe HIE. Babies with mild HIE (scores 0–5) may have subtle signs that the Thompson score doesn’t capture well. That’s why doctors also look at other clues, like the baby’s Apgar scores, cord blood gases, and brain imaging. Even babies with mild HIE may need extra monitoring or follow-up care.

Key takeaways

• The Thompson score is a bedside tool used to assess the severity of hypoxic-ischemic encephalopathy (HIE) in newborns. It ranges from 0 to 22, with higher scores indicating more severe injury.
• It’s calculated based on six clinical signs: tone, level of consciousness, seizures, posture, Moro reflex, and grasp reflex. Each sign is scored from 0 to 3 (or 0 to 2), and the scores are added up.
• The score is divided into three ranges: 0–5 (mild HIE), 6–14 (moderate HIE), and 15–22 (severe HIE). These ranges help guide treatment decisions, like whether to start cooling therapy.
• The Thompson score is widely used because it’s simple and fast, but it has limitations. It’s good at predicting short-term outcomes but less reliable for long-term prognosis. It can also miss mild HIE.
• Other tools, like the Sarnat staging system, Apgar scores, cord blood gases, EEG, and MRI, are used alongside the Thompson score to get a fuller picture of the baby’s condition.
• The Thompson score is a tool, not a crystal ball. It helps doctors decide what to do today, but it doesn’t predict your baby’s future. Every baby is different, and outcomes depend on many factors beyond the score.

From our medical team:

“The Thompson score is one of the first things we calculate when a baby is admitted with suspected HIE, but it’s just the beginning of the story. We use it to guide our next steps — like whether to start cooling therapy — but we also look at the baby’s overall condition, lab results, and brain imaging. And we never make decisions based on the score alone. Parents should remember: this number is a tool for us, not a life sentence for your baby. Our goal is to give every baby the best chance at a healthy future, and the Thompson score is just one part of that process.”

Frequently asked questions

What is the Thompson score for HIE severity assessment?

The Thompson score is a simple scoring system used to assess how severe hypoxic-ischemic encephalopathy (HIE) is in a newborn. It’s based on six clinical signs that doctors can observe at the bedside, like muscle tone, reflexes, and level of consciousness. The score ranges from 0 to 22, with higher scores indicating more severe HIE. It’s widely used in NICUs to guide treatment decisions, like whether to start cooling therapy.

How is the Thompson score calculated?

The Thompson score is calculated by assigning points to six clinical signs: tone (0–3), level of consciousness (0–3), seizures (0–3), posture (0–3), Moro reflex (0–2), and grasp reflex (0–2). The points are added up to give a total score between 0 and 22. For example, a baby who is floppy (2 points), lethargic (2 points), and has weak reflexes (1 point each) might have a score of 7. You can use our Thompson HIE Score calculator to try it yourself.

What does a high Thompson score mean for HIE severity?

A high Thompson score (15–22) means the baby has signs of severe HIE. This can include being comatose, having frequent seizures, or showing signs of brainstem dysfunction (like trouble breathing). Babies with high Thompson scores are very sick and usually need intensive treatment, like cooling therapy. However, the score is a snapshot, not a prediction — some babies with high scores go on to have good outcomes, especially if they respond quickly to treatment.

Can the Thompson score predict HIE outcomes?

The Thompson score is good at predicting short-term outcomes, like whether a baby will have complications in the NICU. But it’s less reliable for long-term outcomes, like cerebral palsy or developmental delays. Some babies with high Thompson scores recover fully, while others with lower scores may have challenges. Other factors — like how quickly treatment was started, whether the baby had seizures, and what brain imaging shows — play a big role in long-term prognosis.

How accurate is the Thompson score for HIE diagnosis?

The Thompson score is a useful tool for assessing HIE severity, but it’s not perfect. It’s best at identifying moderate to severe HIE and is less reliable for mild HIE. It also doesn’t predict long-term outcomes well. That’s why doctors use it alongside other tools, like Apgar scores, cord blood gases, EEG, and MRI, to get a fuller picture of the baby’s condition.

What are the limitations of the Thompson score for HIE assessment?

The Thompson score has a few key limitations. First, it’s less reliable for mild HIE — babies with subtle signs may have low scores even if they need extra monitoring. Second, it’s not a great predictor of long-term outcomes. Third, it’s based on clinical signs that can change quickly, so it’s usually calculated multiple times in the first 48 hours. Finally, it doesn’t account for other factors that affect outcomes, like how quickly treatment was started or what brain imaging shows.

When to call your doctor

The Thompson score is a tool used by doctors in the NICU, not something parents calculate at home. But if your baby has been diagnosed with HIE — or if you’re worried about their development after leaving the NICU — there are some red-flag signs to watch for. Call your pediatrician or a specialist if you notice:

• Your baby is having seizures (rhythmic jerking, staring spells, or unusual movements that don’t stop when you hold the limb).
• Your baby is extremely floppy or stiff, or their muscle tone seems to be getting worse.
• Your baby is hard to wake up, or they’re not responding to sounds or touch like they used to.
• Your baby is having trouble feeding, breathing, or gaining weight.
• Your baby isn’t meeting developmental milestones, like holding their head up, smiling, or rolling over, at the expected ages.

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk to your healthcare provider about any questions or concerns you have about your baby’s health.

References

1. American Academy of Pediatrics (AAP). (2021). Hypoxic-Ischemic Encephalopathy: Management and Prognosis. Pediatrics, 147(6).
2. National Institute for Health and Care Excellence (NICE). (2021). Therapeutic Hypothermia with Intracorporeal Temperature Monitoring for Hypoxic Perinatal Brain Injury. NICE Guideline NG195.
3. Thompson, C. M., et al. (1997). The Value of a Scoring System for Hypoxic-Ischaemic Encephalopathy in Predicting Neurodevelopmental Outcome. Acta Paediatrica, 86(7), 757–761.
4. Sarnat, H. B., & Sarnat, M. S. (1976). Neonatal Encephalopathy Following Fetal Distress: A Clinical and Electroencephalographic Study. Archives of Neurology, 33(10), 696–705.
5. Shankaran, S., et al. (2018). Therapeutic Hypothermia for Neonatal Encephalopathy: A Report from the Children’s Hospitals Neonatal Consortium. Pediatrics, 142(4).
6. Mayo Clinic. (2023). Hypoxic-Ischemic Encephalopathy (HIE).
7. Royal College of Obstetricians and Gynaecologists (RCOG). (2017). Each Baby Counts: 2017 Progress Report.