TheoryFree Surgical Tech CST Practice Test
Take a free Surgical Tech CST practice test for 2026 with questions, answers, explanations, PDF download and timed mock exam links.
Surgical Tech CST Questions
Open each answer, read the explanation, then continue into the full practice flow.
Q1Once a sterile field has been established, which area of a sterile gown is considered sterile?
Show answer
✓ Correct answer: The front from chest to sterile-field level and the sleeves to two inches above the elbow
A sterile gown is considered sterile only in front from the chest to the level of the sterile field and at the sleeves from two inches above the elbow to the cuff. The back and areas below the field level are not sterile.
Q2What is the minimum exposure time to achieve sterilization for wrapped items in a gravity-displacement steam sterilizer operating at 250 degrees F (121 degrees C)?
Show answer
✓ Correct answer: 30 minutes
Gravity-displacement steam sterilization at 250 degrees F (121 degrees C) typically requires a 30-minute exposure for wrapped items, because air removal is slower than in a prevacuum cycle. Higher temperatures (270 degrees F) shorten the required time.
Q3A biological indicator used to monitor steam sterilization most commonly contains spores of which organism?
Show answer
✓ Correct answer: Geobacillus stearothermophilus
Geobacillus stearothermophilus spores are used to test steam and hydrogen peroxide sterilization because they are highly heat-resistant. Bacillus atrophaeus spores are used for dry-heat and ethylene oxide processes.
Q4If a circulator observes a break in sterile technique that no one else noticed, the correct action is to:
Show answer
✓ Correct answer: Announce and correct the contamination immediately
Surgical conscience requires that any break in sterile technique be identified and corrected immediately, regardless of who is watching. Patient safety takes priority over convenience or embarrassment.
Q5Ethylene oxide (EO) gas sterilization is most appropriate for which type of item?
Show answer
✓ Correct answer: Heat- and moisture-sensitive plastics and electronics
Ethylene oxide is a low-temperature chemical sterilant used for heat- and moisture-sensitive items such as plastics, electronics, and fiber-optic cables. Its drawbacks are long aeration times and toxicity.
Q6Items used to set up a sterile field should be opened in what sequence relative to the time of use?
Show answer
✓ Correct answer: As close as possible to the time of surgery
Sterile supplies should be opened as close as possible to the time of use to minimize the chance of airborne contamination. Prolonged exposure of an open field increases the risk of contamination.
Q7When using the closed-gloving technique, the hands:
Show answer
✓ Correct answer: Remain inside the gown sleeves until the gloves are positioned
In closed gloving, the scrubbed person keeps their hands inside the gown sleeves and manipulates the gloves through the fabric, so bare skin never contacts the sterile glove exterior. This reduces contamination risk during self-gloving.
Q8An instrument that contacts intact mucous membranes but does not penetrate sterile tissue (e.g., a vaginal speculum) is classified under the Spaulding system as:
Show answer
✓ Correct answer: Semicritical
Under the Spaulding classification, semicritical items contact mucous membranes or nonintact skin and require at minimum high-level disinfection. Critical items enter sterile tissue and require sterilization.
Q9Immediate-use steam sterilization (IUSS, formerly 'flash') is acceptable when:
Show answer
✓ Correct answer: A full set of backup instruments is unavailable and an item is needed urgently
IUSS is reserved for situations where an item is needed immediately and no sterile replacement is available, such as a dropped instrument with no backup. It should not be used for routine processing or, ideally, for implants.
Q10Which statement about the edges of a sterile drape or wrapper is correct?
Show answer
✓ Correct answer: A one-inch border around the edges is considered nonsterile
A standard rule of sterile technique holds that a one-inch (about 2.5 cm) margin at the edge of a sterile drape or wrapper is considered nonsterile because it is closest to the nonsterile boundary.
Full Surgical Tech CST bank + unlimited mocks
Try 30 questions free. Unlock the complete Surgical Tech CST question bank, every explanation, and unlimited timed mock exams. Practice on any device.
Unlock Surgical Tech CST →