NCMA Surgical Asepsis and Sterile Technique 2 — Questions and Answers
Question 1: What does the term 'strike-through contamination' mean in the context of a sterile field?
- Contamination caused by striking an instrument against a non-sterile surface
- Contamination that occurs when moisture penetrates a sterile drape or wrapping, creating a pathway for microorganisms from the non-sterile surface beneath (Correct answer)
- Contamination from airborne particles landing on the sterile field
- The process by which spores survive autoclaving due to improper technique
Correct answer: Contamination that occurs when moisture penetrates a sterile drape or wrapping, creating a pathway for microorganisms from the non-sterile surface beneath
Strike-through contamination occurs when moisture soaks through a sterile drape or wrapper, creating a 'bridge' between the non-sterile surface below and the sterile surface above, allowing microorganisms to migrate through the wet material.
Strike-through (strikethrough) contamination: when fluids from below saturate the sterile drape, microorganisms wick upward via capillary action through the wet material and contaminate the sterile surface. This is why: waterproof (impermeable) sterile drapes are preferred for wet environments; spilled fluids on sterile fields require immediate drape replacement; sterile supplies should be stored off the floor and away from moisture; wet sterile packages are discarded (cannot verify sterility was maintained); sterile processing pouches must be stored upright in clean, dry areas; autoclaved loads are fully cooled before handling (moisture from cooling steam can wet wrappings). The key principle: any wet sterile drape is considered contaminated.
Question 2: What is the purpose of a biological indicator (BI) in autoclave sterilization quality control?
- To indicate the temperature reached inside the autoclave chamber
- To verify actual destruction of the most resistant bacterial spores, confirming the sterilization cycle was effective (Correct answer)
- To show whether the correct pressure was maintained during the cycle
- To identify which operator ran the sterilization cycle
Correct answer: To verify actual destruction of the most resistant bacterial spores, confirming the sterilization cycle was effective
Biological indicators contain live, heat-resistant bacterial spores (Geobacillus stearothermophilus). After the autoclave cycle, if spores are killed (negative culture), the cycle is confirmed effective. If spores survive (positive culture), the sterilizer is malfunctioning.
Sterilization quality control monitoring: (1) Mechanical monitors — autoclave gauges for temperature, pressure, time (least reliable; only shows parameters, not actual sterilization); (2) Chemical indicators (CI) — color-change tape, strips, or integrators (Class 1–6) that change color when exposed to sterilization conditions; confirms exposure but NOT that sterilization actually occurred; (3) Biological indicators (BI) — highest reliability; contain Geobacillus stearothermophilus (for steam autoclave) or Bacillus atrophaeus (for dry heat/EtO) spores; incubated after cycle — no growth (negative) = sterilization confirmed; growth (positive) = recall all items from that load. AAMI and AORN recommend BIs weekly at minimum, with every implantable load. Medical offices should document BI results.
Question 3: During a sterile procedure setup, you notice the autoclave tape on an instrument pack has changed to a dark color but the expiration date on the package is 2 weeks past. What should you do?
- Use the pack since the chemical indicator shows proper sterilization occurred
- Discard the pack and resterilize the instruments; sterility is time- and event-related — expired packs are considered non-sterile (Correct answer)
- Cut off the expired date label and re-date with today's date
- Use the pack only for minor procedures with low contamination risk
Correct answer: Discard the pack and resterilize the instruments; sterility is time- and event-related — expired packs are considered non-sterile
Sterile packages have expiration dates — past the expiration date, sterility cannot be guaranteed regardless of chemical indicator color. The chemical indicator only shows the pack was processed, not that sterility was maintained through storage.
Sterile pack expiration and storage: Modern sterility concepts are 'event-related' OR 'time-related' depending on facility policy; Event-related: sterility is maintained until the package is opened, contaminated, or its integrity is compromised (torn, wet, punctured); some facilities use this approach with indefinite expiration if properly stored; Time-related: specific expiration dates based on: wrapping material (cloth vs. paper vs. plastic), storage conditions (closed shelves vs. open), handling frequency. Regardless of approach: expired packs must be reprocessed; wet or damaged packages are immediately discarded; packages stored in high-traffic areas have shorter sterility windows. Chemical indicators confirm EXPOSURE to sterilization parameters — not ongoing sterility during storage.
Question 4: When setting up a sterile field for a minor surgical procedure, how far from the edge of the sterile drape must all sterile items be placed?
- Items may be placed anywhere on the drape, including right at the edges
- At least 1 inch (2.5 cm) from the edge, as the border is considered contaminated (Correct answer)
- At least 4 inches from the edge for all items
- Only instruments directly used for cutting must be kept from the edge
Correct answer: At least 1 inch (2.5 cm) from the edge, as the border is considered contaminated
The 1-inch border of a sterile drape is considered contaminated because it may have been touched during opening, touched the non-sterile surface beneath, or be at risk from environmental contamination. All sterile items must remain at least 1 inch inside the border.
Sterile field border principle: The 1-inch (2.5 cm) perimeter of the sterile drape is always considered contaminated because: the outer edge may have touched the non-sterile table surface when being placed; the person opening the package touched the outer wrapper near the edges; the border is the most likely area for strike-through contamination. All sterile instruments, supplies, and the surgeon's hands/instruments must remain in the 'safe zone' — more than 1 inch from the edge. Practical implications: when adding items to the field, they must fall in the center, not near the border; when the physician opens the sterile field, they should stand back from the edge; transfer forceps should place items well within the center.
Question 5: What is the correct method for passing a sterile instrument to the surgeon or physician during a minor procedure?
- Place the instrument on the sterile field for the surgeon to pick up themselves
- Hand the instrument handle-first to the physician using sterile transfer forceps or sterile-gloved hands, ensuring the tip remains sterile (Correct answer)
- Wipe the instrument with an alcohol pad and hand it directly
- Announce the instrument name and toss it gently toward the surgeon's sterile field
Correct answer: Hand the instrument handle-first to the physician using sterile transfer forceps or sterile-gloved hands, ensuring the tip remains sterile
Sterile instruments are passed handle-first, using sterile transfer forceps or sterile-gloved hands. This allows the physician to grasp the handle without the medical assistant touching the tip (which contacts the patient's sterile wound) and maintains sterile technique.
Instrument passing technique during sterile procedures: (1) Orient the instrument handle toward the surgeon's receiving hand; (2) Announce the instrument name before placing/passing; (3) Use sterile gloves or sterile transfer forceps; (4) Firm but controlled placement in the surgeon's hand — the surgeon needs to feel secure 'snap'; (5) Do not reach over the sterile field; (6) Maintain awareness of tip orientation — tips should never point upward (fluid contamination) or toward the patient unnecessarily. Instrument passing in order of procedure: ensure all anticipated instruments are on the sterile field before starting; know the procedure sequence to anticipate needs; maintain count of sharp instruments per safety protocol. Medical assistants serving as scrub assistants must master instrument identification and passing technique.
Question 6: After completing a minor surgical procedure, how should contaminated surgical instruments be initially handled before autoclaving?
- Rinse with tap water and place directly in the autoclave
- Wear heavy-duty PPE, rinse or pre-soak instruments to remove gross contamination, then clean (manually or in ultrasonic cleaner), rinse, dry, inspect, wrap, and then sterilize (Correct answer)
- Soak in bleach solution for 24 hours before rinsing
- Place instruments in an open tray and autoclave immediately without cleaning
Correct answer: Wear heavy-duty PPE, rinse or pre-soak instruments to remove gross contamination, then clean (manually or in ultrasonic cleaner), rinse, dry, inspect, wrap, and then sterilize
Reprocessing sequence for surgical instruments: (1) Wear PPE (heavy utility gloves); (2) Rinse/pre-soak (enzymatic solution) to prevent drying of organic material; (3) Clean (manual scrubbing or ultrasonic cleaner); (4) Rinse thoroughly; (5) Dry completely; (6) Inspect for function and damage; (7) Package/wrap; (8) Sterilize by autoclave.
Instrument reprocessing must follow the correct sequential steps — sterilization CANNOT compensate for inadequate cleaning: (1) Pre-cleaning/pre-soak — enzymatic detergent solution prevents biofilm and blood from drying; (2) Decontamination cleaning — manual (soft-bristled brush, point of care) or ultrasonic cleaner (cavitation removes debris from lumens and hinges); (3) Rinse — with distilled or deionized water; (4) Inspection — check hinges, ratchets, tips, and cutting edges for function and corrosion; (5) Lubrication — instrument milk for hinges; (6) Packaging — double-wrap in surgical grade wrapping paper, indicate lot number, sterilization date, expiration; (7) Sterilize. Organic material (blood, tissue) acts as a biofilm barrier preventing steam/chemicals from reaching microorganisms — cleaning is mandatory.
NCMA Surgical Asepsis and Sterile Technique 2
What does the term 'strike-through contamination' mean in the context of a sterile field?