All of the Following Are Components of Scene Size-Up Except?
The exception is checking the patient's responsiveness. Scene size-up covers scene safety, standard precautions/PPE, the mechanism of injury or nature of illness, the number of patients, and the need for additional resources. Responsiveness is assessed later, during the primary assessment.
The answer
On this classic EMT/first-aid question, the choice that is NOT part of scene size-up is checking the patient's level of responsiveness (or any similar hands-on patient assessment, such as checking a pulse or airway). Those steps belong to the primary assessment, which begins only after the scene has been sized up.
Scene size-up is the first phase of patient assessment, and it happens before you reach or touch the patient. Its purpose is to make the scene safe and understand what you are walking into. The recognized components are:
- Scene safety — is it safe for you, the patient, and bystanders? Look for traffic, fire, electrical hazards, unstable structures, violence, or hazardous materials.
- Standard precautions / PPE — determine and put on the appropriate body substance isolation: gloves, eye protection, gown, or mask.
- Mechanism of injury (MOI) or nature of illness (NOI) — decide whether this is a trauma or medical call and how the injury or illness likely occurred.
- Number of patients — count how many people are involved so no one is missed.
- Additional resources — decide whether you need more ambulances, fire, rescue, law enforcement, or specialized teams.
Why responsiveness is the exception
Everything in scene size-up is about situational awareness before patient contact. Checking responsiveness requires you to approach and interact with the patient, which is why it is the opening step of the primary (initial) assessment, not scene size-up. The standard assessment sequence is: scene size-up, then primary assessment (general impression, level of consciousness/AVPU, airway, breathing, circulation), then history and secondary assessment, then reassessment.
This distinction is exactly the content gap that trips students up. Because different exam versions swap the answer options, you cannot memorize one letter. Instead, ask: "Does this action happen before I touch the patient?" If yes, it is scene size-up. If it requires assessing the patient's condition, airway, breathing, circulation, mental status, it is the primary assessment.
Ruling out the distractors
- Scene safety — a core size-up component; keep the answer.
- Standard precautions / PPE — part of size-up; you choose protection based on what the scene shows.
- Determining the mechanism of injury or nature of illness — a size-up component.
- Number of patients — a size-up component, driving triage and resource decisions.
- Requesting additional resources — a size-up component.
- Checking responsiveness / pulse / airway — the EXCEPTION; this is primary assessment.
If a version instead lists something like "bandaging a wound" or "taking a blood pressure," that too would be the exception, since those come later in care. The unifying rule remains: scene size-up is the pre-contact, safety-and-scope phase.
| Ensure scene safety | Yes | Scene size-up |
| Take standard precautions (PPE) | Yes | Scene size-up |
| Determine MOI / nature of illness | Yes | Scene size-up |
| Count number of patients | Yes | Scene size-up |
| Call for additional resources | Yes | Scene size-up |
| Check patient responsiveness | No | Primary assessment |
Frequently asked
What are the five components of scene size-up?
Scene safety, standard precautions (appropriate PPE/body substance isolation), determining the mechanism of injury or nature of illness, identifying the number of patients, and determining the need for additional resources such as more units, fire, or law enforcement.
What is the difference between scene size-up and primary assessment?
Scene size-up happens before patient contact and focuses on safety, PPE, mechanism of injury, patient count, and resources. The primary assessment begins once you reach the patient and evaluates responsiveness, airway, breathing, and circulation to find immediate life threats.
What is scene safety in EMS?
Scene safety is the ongoing evaluation of hazards to the rescuer, patient, and bystanders, such as traffic, fire, downed power lines, unstable surfaces, violence, or hazardous materials. If a scene is unsafe, you do not enter until it is made safe.
When do you determine mechanism of injury?
You determine the mechanism of injury during scene size-up, before touching the patient. Observing the scene, such as vehicle damage or a fall height, helps predict likely injuries and guides how you conduct the primary and secondary assessments.