6.1 Principles of Surgical Asepsis, Sterile Field Maintenance & Gowning/Gloving
Key Takeaways
- Sterile gown boundaries extend from the chest level down to the level of the sterile field, and from 2 inches above the elbow to the proximal cuff.
- Unscrubbed team members must maintain a minimum distance of at least 12 inches (1 foot) from any sterile field or scrubbed team member at all times.
- Only the top horizontal surface of a draped table is considered sterile; any table drape extending below the table top is classified as unsterile.
- Closed gloving is mandatory for initial gowning and gloving to prevent hand contact with the outside of the gown cuff or glove exterior.
- The back of the surgical gown, shoulders, necklines, axillae, and gown cuffs (once hands pass through) are unsterile zones.
6.1 Principles of Surgical Asepsis, Sterile Field Maintenance & Gowning/Gloving
Surgical asepsis forms the foundational cornerstone of perioperative nursing practice. The primary goal of surgical asepsis (also known as sterile technique) is to prevent the introduction of microorganisms into open surgical wounds, thereby preventing surgical site infections (SSIs) and patient morbidity. Unlike medical asepsis (clean technique), which seeks to reduce the number and spread of pathogens, surgical asepsis demands the complete absence of all microorganisms, including bacterial spores, within designated areas known as the sterile field.
Adherence to sterile technique relies heavily on individual professional accountability, referred to as a surgical conscience. A surgical conscience requires immediate admission and correction of any real or potential breach in sterile technique, regardless of who caused it or how inconvenient the corrective action may be.
Core Tenets of Surgical Asepsis
According to the Association of periOperative Registered Nurses (AORN) Guidelines for Perioperative Practice, five fundamental tenets govern surgical asepsis:
- Items used within a sterile field must be sterile. If there is any doubt regarding the sterility of an item, it must be considered unsterile.
- Sterile items become unsterile when touched by unsterile items or persons. Direct contact between a sterile and unsterile object results in immediate contamination.
- Sterile items must be created and maintained in a controlled environment. Sterile fields are established as close to the time of use as possible and continuously monitored.
- Members of the surgical team must be appropriately scrubbed, gowned, and gloved. Team members moving within or around a sterile field must adhere to strict behavioral and movement protocols.
- Moisture causes contamination. Microorganisms travel through moisture by capillary action, a phenomenon termed strike-through contamination.
Sterile Field Boundaries & Topography
Understanding the exact physical parameters of what is sterile versus unsterile on personnel and equipment is essential for intraoperative safety and CNOR exam success.
| Equipment / Personnel | Sterile Area / Boundary | Unsterile Area / Boundary | Clinical & Exam Rationale |
|---|---|---|---|
| Surgical Gown | Front of gown from chest level down to the level of the sterile field (table height); sleeves from 2 inches above the elbow to the proximal cuff. | Back of gown, shoulders, neckline, axillae, undersides of arms, and knitted cuffs (once hands pass through). | Movement and air currents make non-visible gown areas vulnerable to bacterial shedding; back wrap-around flaps do NOT make the back sterile. |
| Draped Sterile Table | Only the top horizontal surface of the table draped with a sterile barrier. | Any drape hanging over the table edge, sides, or bottom of the drape. | Items extending below table level are out of direct sight and vulnerable to air currents and contact with non-sterile equipment. |
| Mayo Stand | Top surface and upper portion of the stand covered by the cylindrical sterile drape. | Lower telescoping post and foot-base of the Mayo stand. | Non-draped vertical supports are in contact with or near the floor, which is heavily contaminated. |
| Sterile Basin / Solution Drapes | Inside rim and inner liquid-holding basin surface. | Outer bottom of basin and drape edges hanging below table height. | Fluid transfers must occur without touching outer non-sterile container rims. |
Gown Sterile Boundaries Deep-Dive
A common CNOR exam trap concerns the surgical gown. Even though modern wrap-around gowns cover the back of the surgeon or scrub nurse, the back of the gown is ALWAYS considered unsterile. The sterile zone on the front of the gown starts at the chest level (not the neck or collarbone) and ends at the level of the sterile field (operating table height).
The sleeves are sterile from 2 inches above the elbow down to the wrist seam. The knitted cuffs of the gown are considered unsterile once the hands have passed through them during open gloving or routine use, because cuffs absorb moisture and collect skin microorganisms. Knitted cuffs must always be completely covered by the gauntlet of sterile gloves.
Rules of Movement and Positioning Around the Sterile Field
Strict movement protocols minimize airborne contamination and accidental contact breaches within the operating room:
- Scrubbed Personnel Movement: Scrubbed team members must stay close to the sterile field. When changing positions relative to one another, scrubbed personnel must pass either face-to-face (maintaining visual contact with the front of gowns) or back-to-back (ensuring unsterile backs touch only unsterile backs). Scrubbed personnel must never turn their backs to the sterile field.
- Unscrubbed Personnel Movement: Unscrubbed team members (such as the circulating nurse or anesthesia provider) must maintain a minimum distance of 12 inches (1 foot) from any sterile field, draped table, or scrubbed person. Unscrubbed staff must face the sterile field when approaching it and never walk between two sterile fields.
- Hands and Arms Positioning: Scrubbed personnel must keep their hands and arms above waist level and below chest level at all times, folded in front of the body or resting on the sterile field. Hands must never be dropped below table level or placed in the axillary region.
Gowning and Gloving Techniques
Correct gowning and gloving prevents hand skin microbiota from contaminating the exterior of the sterile gown and gloves.
Closed Gloving Technique
Closed gloving is the mandatory method for initial gowning and gloving prior to surgery. In this technique, the hands remain inside the gown sleeves and do not pass through the knitted cuffs until the glove is positioned and secured over the cuff.
- The gowned individual keeps hands concealed within the gown sleeves.
- The glove cuff is aligned with the gown cuff, palm to palm, with the fingers of the glove pointing toward the elbow.
- The glove cuff is pulled over the gown cuff while working from inside the sleeve.
- The hand is pushed through the gown cuff into the glove.
Open Gloving Technique
Open gloving is used when changing a contaminated glove intraoperatively (if assisted gloving is unavailable) or during minor procedures where a gown is not required (e.g., Foley catheter insertion, simple wound dressing). In open gloving, the bare hand touches only the inside folded cuff of the glove. Bare skin must never touch the outer sterile surface of the glove.
Assisted Gloving
When a scrubbed team member needs a glove replaced during an active procedure, assisted gloving by another scrubbed team member is the gold standard. The assisting team member opens the glove cuff wide with thumbs protected under the cuff fold, allowing the recipient to insert their hand cleanly without risk of cuff contact.
Environmental Threats to Sterile Field Integrity
- Strike-Through Contamination: Occurs when liquids soak through a sterile drape or gown, creating a liquid bridge that allows microorganisms to migrate from unsterile surfaces beneath to the sterile field above. Fluid-resistant or fluid-impervious drapes and gowns must be utilized.
- Air Movement & Traffic: Every movement of personnel, opening of OR doors, or shaking of drapes creates air turbulence that lifts skin squames and dust particles into the air. Sterile fields should be opened as close to the start of the procedure as possible and must never be left unattended.
- Doubt Equals Contamination: If a sterile drape or package is torn, wet, expired, or lacking a sterile indicator change, the item is contaminated and must be discarded immediately.
CNOR Exam Traps & High-Yield Pearls
- Gown Back: The back of a surgical gown is unsterile, even if it is a wrap-around gown tied securely.
- Unattended Sterile Field: A sterile field that is left unmonitored is considered contaminated. It cannot be "re-inspected" or assumed safe.
- Distance Rule: 12 inches (30 cm) is the absolute minimum safe distance for unscrubbed staff around a sterile field.
- Cuff Status: The knitted wrist cuffs of the surgical gown are unsterile once hands pass through them; gloves must completely cover cuffs.
During a total hip arthroplasty, the circulating nurse observes a scrubbed surgical technologist resting their hands in their axillary region while waiting for the implant. What is the most appropriate action by the nurse?
A circulating nurse is delivering sterile saline onto a sterile field. Which technique correctly adheres to sterile field boundary principles?
During an abdominal laparotomy, a scrubbed assistant punctures their right glove on a suture needle. Which procedure represents the correct protocol for glove replacement?