The Ultimate CST Practice
Exam: Questions, Answers, and
In-Depth Rationales
Section 1: Perioperative Environment & Safety (Questions 1-20)
1. What is the minimum acceptable room air exchange rate per hour for an operating
room?
A) 10
B) 15
C) 20
D) 25
Answer: B) 15
Rationale: The recommended minimum air exchanges for an operating
room is 15 per hour, with at least 3 of those being fresh outside air. This helps to dilute and
remove airborne contaminants.
, 2. The relative humidity in an operating room should be maintained between:
A) 20-40%
B) 30-60%
C) 50-70%
D) 60-80%
Answer: B) 30-60%
Rationale: The recommended relative humidity in the OR suite is 30% to
60%. This range minimizes the risk of bacterial growth and static electricity while maintaining
patient normothermia.
3. Which of the following is a Class A fire extinguisher used for?
A) Flammable liquids
B) Electrical fires
C) Combustible metals
D) Ordinary combustibles (wood, paper, cloth)
Answer: D) Ordinary combustibles (wood, paper, cloth)
Rationale: Class A extinguishers are for ordinary combustibles. Class B is for
flammable liquids, Class C is for electrical fires, and Class D is for combustible metals.
4. The "RACE" acronym for fire safety stands for Rescue, Alarm, Confine, and:
A) Extinguish
B) Evacuate
C) Emergency
D) Evaluate
, Answer: A) Extinguish
Rationale: RACE is the standard fire response protocol. Rescue anyone in
immediate danger, Alarm (activate the fire alarm), Confine the fire (close doors/windows), and
Extinguish if it is safe to do so, or Evacuate.
5. What is the primary purpose of the "time-out" before the incision is made?
A) To confirm the patient's insurance information
B) To perform a final verification of the correct patient, procedure, site, and position
C) To allow the surgeon to review the patient's lab results
D) To check the anesthesia machine
Answer: B) To perform a final verification of the correct patient, procedure, site, and
position
Rationale: The "time-out" is the final step of the Universal Protocol. It is
performed immediately before the procedure begins and involves the entire surgical team to
confirm critical information and prevent wrong-site, wrong-procedure, and wrong-patient
surgery.
6. A patient in the lithotomy position is at the greatest risk for developing:
A) Brachial plexus injury
B) Sciatic nerve palsy
C) Common peroneal nerve palsy
D) Ulnar nerve palsy
Answer: C) Common peroneal nerve palsy
, Rationale: The common peroneal nerve, which wraps around the head of
the fibula, is vulnerable to compression from the leg holders used in the lithotomy position. This
can lead to foot drop.
7. An electrical current passing from the active electrode to the dispersive electrode is
known as the:
A) Circuit
B) Fulguration
C) Desiccation
D) Spark
Answer: A) Circuit
Rationale: For an electrical circuit to be complete, current must flow from
the generator through the active electrode, into the patient, and out through the dispersive
(return) electrode back to the generator.
8. What is the correct position for a patient undergoing a thyroidectomy?
A) Supine with a shoulder roll
B) Fowler's
C) Prone
D) Trendelenburg
Answer: A) Supine with a shoulder roll
Rationale: Placing a shoulder roll under the patient's shoulders allows for
hyperextension of the neck, which brings the thyroid gland forward and makes it more
accessible for the surgeon.
Exam: Questions, Answers, and
In-Depth Rationales
Section 1: Perioperative Environment & Safety (Questions 1-20)
1. What is the minimum acceptable room air exchange rate per hour for an operating
room?
A) 10
B) 15
C) 20
D) 25
Answer: B) 15
Rationale: The recommended minimum air exchanges for an operating
room is 15 per hour, with at least 3 of those being fresh outside air. This helps to dilute and
remove airborne contaminants.
, 2. The relative humidity in an operating room should be maintained between:
A) 20-40%
B) 30-60%
C) 50-70%
D) 60-80%
Answer: B) 30-60%
Rationale: The recommended relative humidity in the OR suite is 30% to
60%. This range minimizes the risk of bacterial growth and static electricity while maintaining
patient normothermia.
3. Which of the following is a Class A fire extinguisher used for?
A) Flammable liquids
B) Electrical fires
C) Combustible metals
D) Ordinary combustibles (wood, paper, cloth)
Answer: D) Ordinary combustibles (wood, paper, cloth)
Rationale: Class A extinguishers are for ordinary combustibles. Class B is for
flammable liquids, Class C is for electrical fires, and Class D is for combustible metals.
4. The "RACE" acronym for fire safety stands for Rescue, Alarm, Confine, and:
A) Extinguish
B) Evacuate
C) Emergency
D) Evaluate
, Answer: A) Extinguish
Rationale: RACE is the standard fire response protocol. Rescue anyone in
immediate danger, Alarm (activate the fire alarm), Confine the fire (close doors/windows), and
Extinguish if it is safe to do so, or Evacuate.
5. What is the primary purpose of the "time-out" before the incision is made?
A) To confirm the patient's insurance information
B) To perform a final verification of the correct patient, procedure, site, and position
C) To allow the surgeon to review the patient's lab results
D) To check the anesthesia machine
Answer: B) To perform a final verification of the correct patient, procedure, site, and
position
Rationale: The "time-out" is the final step of the Universal Protocol. It is
performed immediately before the procedure begins and involves the entire surgical team to
confirm critical information and prevent wrong-site, wrong-procedure, and wrong-patient
surgery.
6. A patient in the lithotomy position is at the greatest risk for developing:
A) Brachial plexus injury
B) Sciatic nerve palsy
C) Common peroneal nerve palsy
D) Ulnar nerve palsy
Answer: C) Common peroneal nerve palsy
, Rationale: The common peroneal nerve, which wraps around the head of
the fibula, is vulnerable to compression from the leg holders used in the lithotomy position. This
can lead to foot drop.
7. An electrical current passing from the active electrode to the dispersive electrode is
known as the:
A) Circuit
B) Fulguration
C) Desiccation
D) Spark
Answer: A) Circuit
Rationale: For an electrical circuit to be complete, current must flow from
the generator through the active electrode, into the patient, and out through the dispersive
(return) electrode back to the generator.
8. What is the correct position for a patient undergoing a thyroidectomy?
A) Supine with a shoulder roll
B) Fowler's
C) Prone
D) Trendelenburg
Answer: A) Supine with a shoulder roll
Rationale: Placing a shoulder roll under the patient's shoulders allows for
hyperextension of the neck, which brings the thyroid gland forward and makes it more
accessible for the surgeon.
