Principles of Surgical Asepsis

Chapter 1

Principles of Surgical Asepsis

Aseptic and Sterile Techniques

Infection remains one of the most potentially devastating and challenging complications of surgery. Infection in a veterinary surgical practice may occur during surgery or at any time during hospitalization. It is incumbent upon the veterinary practitioner and staff to ensure that all possible measures are taken to reduce the risk of iatrogenic infection. The terms aseptic technique and sterile technique are used interchangeably by some authors (Box 1-1), but in strict terms, asepsis is defined as the absence of microorganisms that cause disease, whereas sterile is defined as being free of all living microorganisms. Therefore, techniques to maintain sterility are more appropriate for the operating room (OR) setting, but aseptic principles should be applied to the entire hospital. Outside the OR, these techniques have been referred to as medical asepsis and are designed to protect both the patient and hospital staff.

image Box 1-1



Prevention of sepsis by exclusion, destruction, or inhibition of growth or multiplication of microorganisms from body tissues and fluids.


Inorganic chemical compounds that combat sepsis by inhibiting the growth of microorganisms without necessarily killing them. Used primarily on skin to stop the growth of resident flora.


Absence of microorganisms that cause disease.

Aseptic technique

Method to prevent contamination by microorganisms.


A material used to reduce or inhibit the migration or transmission of microorganisms in the environment: personnel attire and gowns, furniture and patient drapes, equipment and supply packaging, and ventilating filters.


Carrying or infected by microorganisms.


Transmission of microorganisms from patient to patient or from inanimate object to patient.


Cleaning and disinfecting or sterilizing processes carried out to make contaminated items safe to handle.


Chemical or mechanical (friction) destruction of pathogens.

Irreducible minimum

Microbial burden cannot get any lower. Item is sterile to its highest degree.

Spatial relationships

Awareness of sterile, unsterile, clean, and contaminated areas, objects, and individuals and their proximity to each other.

Standard precautions

Procedures followed to protect personnel from contact with the blood and body fluids of patients.


Free of living organisms.

Sterile field

Area around the site of incision into tissue or the site of introduction of an instrument into a body orifice that has been prepared using sterile supplies and equipment.

Sterile technique

Method by which contamination with microorganisms is prevented to maintain sterility throughout the surgical procedure.

Terminal sterilization and disinfection

Procedures carried out for the destruction of pathogens at the end of the surgical procedure in the operating room (OR) after the patient has been removed.

Modified from Philips N: In: Berry and Kohn’s operating room technique, ed 11, St Louis, Mo., 2007, Mosby.

The complete absence of microorganisms cannot be achieved in a hospital environment, but use of aseptic techniques substantially aids in control of pathogens and decreases the risk of infection for patients and staff. When specific procedures are discussed, aseptic technique has been referred to as clean technique. Sterile technique (see Box 1-1) applies to work performed in a sterile field. The higher level of protection in a sterile field is critical because the natural defenses of the patient are breached by surgical incision, puncture, or introduction of instruments into the vascular system. Studies in human surgical practice have attempted to determine when sterile technique versus clean technique is necessary for certain minor procedures. For example, arthrocentesis (see pp. 1217-1218) performed under sterile technique might require the use of sterile gloves, a sterile patient preparation kit, and a small drape, whereas the same procedure performed using clean or aseptic technique would require only nonsterile gloves and an alcohol wipe. The differences in time and cost involved for sterile technique versus clean technique can be substantial.

Transmission of Microorganisms

Numerous sources of microorganisms are found in veterinary hospitals, but as in human hospitals, the hospital staff is the most likely means of transmission. Other sources of transmission include contaminated instruments and the environment. The specific means of transmission from staff to patient include airborne, droplet, and contact. Airborne and droplet types of transmission of microorganisms are common in human hospitals but less common in veterinary hospitals because of the low incidence of reverse zoonosis (transmission of disease from human to nonhuman animals). Contact, whereby pathogenic microorganisms are transferred to the patient from another patient or from an environmental source, is the most common method of microorganism transmission in the veterinary hospital. During surgery, contact may also be responsible for transmission of microorganisms from the patient’s normal sources of bacteria such as the skin or nasopharynx to the surgical wound.

Sources of contamination

Sources of contamination may be divided into animal sources and inanimate sources.

Principles of Hospital Asepsis

Minimization of infection in a surgery practice involves applying principles of aseptic technique throughout the hospital. Goals are to minimize sources of contamination and to block transmission of microorganisms. Some techniques that aid in reduction of the quantity of pathogenic microorganisms are listed in Box 1-2.

Sterile Technique

All surgical procedures are ideally performed under sterile conditions. Sterile technique is designed to prevent the transmission of microorganisms into the body during surgery or other invasive procedures. General principles of aseptic technique should be familiar to all personnel working in and around the surgical environment (Table 1-1). These principles include the following: (1) use only sterile items within a sterile field; (2) sterile (scrubbed) personnel are gowned and gloved; (3) sterile personnel operate within a sterile field (sterile personnel touch only sterile items or areas, unsterile personnel touch only unsterile items or areas); (4) sterile drapes are used to create a sterile field; (5) all items used in a sterile field must be sterile; (6) all items introduced onto a sterile field should be opened, dispensed, and transferred by methods that maintain sterility and integrity; (7) a sterile field should be maintained and monitored constantly; and (8) surgical staff should be trained to recognize when they have broken technique and should know how to remedy the situation.

image TABLE 1-1

General Rules of Aseptic Technique

Surgical team members remain within the sterile area. Movement out of the sterile area may encourage cross-contamination.
Talking is kept to a minimum. Talking releases moisture droplets laden with bacteria.
Movement in the operating room (OR) by all personnel is kept to a minimum; only necessary personnel should enter the operating room. Movement in the OR may encourage turbulent airflow, resulting in cross-contamination.
Nonscrubbed personnel do not reach over sterile fields. Dust, lint, or other vehicles of bacterial contamination may fall on the sterile field.
Scrubbed team members face each other and the sterile field at all times. A team member’s back is not considered sterile even if wearing a wraparound gown.
Equipment used during surgery must be sterilized. Unsterile instruments may be a source of cross-contamination.
Scrubbed personnel handle only sterile items; nonscrubbed personnel handle only nonsterile items. Nonscrubbed personnel and nonsterile items may be sources of cross-contamination.
If the sterility of an item is questioned, it is considered contaminated. Nonsterile, contaminated equipment may be a source of cross-contamination.
Sterile tables are sterile only at table height. Items hanging over the table edge are considered nonsterile because they are out of the surgeon’s vision.
Gowns are sterile from mid-chest to waist and from gloved hand to 2 inches above the elbow. The back of the gown is not considered sterile even if it is a wraparound gown.
Drapes covering instrument tables or the patient should be moisture proof. Moisture carries bacteria from a nonsterile surface to a sterile surface (strike-through contamination).
If a sterile object touches the sealing edge of the pouch that holds it during opening, it is considered contaminated. Once opened, sealed edges of pouches are not sterile.
Sterile items within a damaged or wet wrapper are considered contaminated. Contamination can occur from perforated wrappers or from strike-through from moisture transport.
Hands may not be folded into the axillary region; rather, they are clasped in front of the body above the waist. The axillary region of the gown is not considered sterile.
If the surgical team begins the surgery seated, they should remain seated until the surgery has been completed. The surgical field is sterile only from table height to the chest; movement from sitting to standing during surgery may promote cross-contamination.

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Sep 11, 2016 | Posted by in SMALL ANIMAL | Comments Off on Principles of Surgical Asepsis

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