EMT Training - Become an Emergency Medical Technician

Scene Size-Up

Scene Size Up Title Graphic

Sizing up a scene is an important skill that EMS perform at every call. The Scene Size-up is the first section of both the Patient Assessment/Management Medical and Trauma skills as set forth by the National Registry of Emergency Medical Technicians. It can be easy to habitually repeat “BSI, scene safe” while practicing skills. Over time they can become a requirement for passing a test, rather than a way to protect yourself, your crew, and your patient.


Learning the steps to pass the NREMT while integrating them into real world scenarios is a good way to stay sharp and stay safe in the field. 

→ This page will go over scene size-up for the patient assessment portion of the psychomotor exam first. Then it will focus on reviewing scene size-up steps for the NREMT cognitive exam and real life scenarios.

Here are the scene size-up steps exactly as they appear on the NREMT psychomotor exam skill sheet.


Scene Size-Up Steps

  • Takes or verbalizes appropriate PPE precautions


  • Determines the scene/situation is safe 
  • Determines the mechanism of injury/nature of illness
  • Determines the number of patients
  • Requests additional EMS assistance if necessary 
  • Considers stabilization of the spine


Each step listed above is valued at one point during the EMT psychomotor exam. However, you can be failed for missing Critical Criteria steps in the patient assessment.

During the patient assessment portions of your NREMT psychomotor testing you may be able to get away with stating BSI or PPE. However, a better way to earn the confidence of your proctor is to state:

“I’m putting on my gloves for BSI personal protection” while you put on your gloves.

If your testing scenario has a MVA near a highway, instead of just saying PPE, you can say:

“I put on a reflective vest for PPE and safety.”

These small gestures can indicate to your proctor that you understand everything you are saying. This lets them know you aren’t just parroting words you memorized.


For NREMT patient assessment testing scenarios, it’s common to get through the scene size up pretty quickly. The important thing is to hit each of the six scene size-up steps listed above. You can do this by making statements, asking questions or through demonstrations.


NREMT Scene Size-Up Samples 

Here are some examples of how to get through the EMT scene size-up portion of the NREMT test.


Nature of Illness Scene Size-Up


You are dispatched to the home of a 62 year-old female complaining of chest pains for 12 minutes.


“I’m putting on my gloves for BSI. I’m checking to make sure my scene is safe.” (Look to your proctor for any verbal response that your scene is not safe.) “Ok my scene is safe.” You may want to introduce yourself to the patient at this time and ask questions to determine NOI.

“The nature of illness is chest pain and I have one patient. I’m going to call for an ALS unit. I’ve considered C-spine, but don’t find it necessary based on the patient’s complaint of chest pain.”

In this scenario the EMT is able to quickly verbalize most of the scene size-up and can now move on to the primary survey.


Psychomotor Exam Tip:

When checking for scene safety, the proctor may say there is an angry dog barking, or you hear loud arguing or you smell smoke. This means you need to take steps to make this scene safe. For example:  You may need to call animal control, call law enforcement  investigate the smoke smell, call the Fire Department and evacuate with patient.


Mechanism of Injury Scene Size-Up 


You are dispatched to a street address where a 24 year-old male is lying supine on the sidewalk after being shot once.


“I’m putting on gloves for BSI and I’m checking to make sure the scene is safe.” “The scene is safe. The mechanism of injury is a gunshot wound (GSW).” “It appears I have one patient. I’m going to call for an ALS unit and have my partner hold c-spine.”


EMT Scene Size-Up


Now that we’ve covered the practical test, let’s talk about how the scene size-up skill is used during the cognitive exam and in the real world. In real life scenarios scene size-up steps are the same, but we can go more in depth here instead of learning what to tell the proctor.


As a first responder approaching a scene you want to evaluate any information you have. Use the information dispatch gives you to predict what PPE will be needed and what issues you can expect.


For example, you might approach a call for SOB differently than a motor vehicle accident. You’d expect the SOB to be a NOI call and not a trauma. The MVA call may have multiple patients, it might not be secured yet and you might need to call in a Fire unit for a vehicle extraction.


Stay flexible and read the scene.


That SOB call could be a construction worker experiencing SOB after falling 3 stories, which makes it a trauma.


Gather and evaluate information on arrival and during the call while keeping an open mind.


EMT Scene Size-Up Steps


Six Scene Size-Up Steps

  1. Safety
  2. BSI/PPE
  3. NOI/MOI
  4. # of Patients
  5. Additional Units
  6. C-spine


These steps are evaluated and done on arrival and throughout the entire incident. Changes can happen on scene in a moment so it’s important to stay aware of surroundings and respond accordingly.



Safety is always a priority for EMS personnel.

Providing prehospital care can inherently mean scenes that are unsafe and unpredictable. It’s important for EMTs and paramedics to be able to identify hazards and respond appropriately.


> Is the scene safe for yourself, your crew, bystanders, and the patient?  


As an EMT it can be difficult to wait outside for another agency to arrive and secure a scene. However, it’s not worth the risk of getting hurt by rushing in because if you get inured:

  • You can’t care for the patient.
  • You will require medical assistance that could have gone to the original patient. 


Options For Unsafe Scenes

  • Wait outside the scene. Stay at a safe location until it can be secured by an outside agency, like Fire or Police.
  • Make the scene safe. Ex: place traffic cones.
  • Retreat from the scene if it becomes unsafe after entering.
  • Barricade yourself and the patient if the scene becomes unsafe. Find the safest location available if you can’t safely retreat, and wait until other agencies arrive.


 EMS must determine what the best decision is on scene.


Body substance isolation / Personal Protective Equipment

Body substance isolation and personal protective equipment is gear that can be worn for protection on scene. BSI gear protects EMS workers from potential pathogen exposure.


Body Substance Isolation Gear


Some examples of PPE gear include: 

• Gloves
• Goggles
• Boots
• Gowns
• Face mask
• Reflective Vest  

BSI is an important step in the scene size-up. It should be done anytime you may come in contact with infectious agents or bodily fluids.  

OSHA has made Universal Precautions and the CDC has created Standard Precautions and Standards of Use for PPE to help protect workers from infection diseases.

Follow these guidelines and treat any bodily fluid as if it has the potential for infection.


Nature of Illness / Mechanism of Injury

This step of the scene size-up is when the first responder should be asking themselves:

  • What is wrong with this patient?
  • What type of patient assessment will I perform? 

The answers will determine how the rest of the patient assessment goes.


EMTs and paramedics can learn what’s wrong with the patient by:

Using information given by dispatch
Asking the patient
Asking family
Talking with bystanders
Looking for clues on scene


If the chief complaint is medical, what is the nature of the illness? Determine whether the illness is caused by pre-existing health issues or environmental factors.


If the chief complaint is trauma, determine what injured the patient and predict what underlying injuries are likely based on the force that caused the trauma.


Number of Patients

Determining the number of patients can be a clue that a scene is unsafe and indicate what additional resources will need to be called in the next step of the scene size-up.


If there are multiple patients down complaining of similar symptoms it could indicate an environmental issue like a gas leak or chemical weapon. When multiple people are injured on scene first responders should make sure that whatever injured the patients is no longer a threat to first responders.


Need For Additional Resources

During this step in the scene size-up first responders must decide whether they need to call in more EMS units and additional resources from other agencies.  


Swat Hazmat Fire Police


Whenever possible the EMT should identify the need for additional units quickly and call for more units prior to contact with patient.


Here are some examples of additional resources that an EMT may need to call to a scene.

  • ALS Unit: Higher level of care
  • More transport units: Multiple patients
  • Swat or Tactical Team: Active shooter
  • Hazmat Team: Hazardous spill
  • Law Enforcement: Secure a scene
  • Fire Department: Vehicle extraction or fire


C-Spine Precautions

This step in the scene size-up involves determining whether the patient needs cervical spine precautions. Determining the mechanism of injury from trauma can indicate to the first responder that C-spine precautions need to be taken.


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