1. Isolate surgical site from contaminated areas with an impermeable barrier
  2. Provide a sterile working area  

Draping materials

  • ideal barrier material is impermeable, easy to sterilize and economical 
  • two basic types:  Cloth (woven) or Disposable (nonwoven)

Cloth (woven)

Cloth (woven)

  •  typically cotton muslin
  • tightness of weave is measured in threads per square inch
    • the higher the number, the tighter the weave and the better the barrier
    • 140 threads per square inch: not  effective barrier (pore size too big)
    • 270 threads per square inch: effective if dry but bacteria can penetrate when wet unless treated with water resistant coating
  • reusable
  • economical depending on cost of laundering

Disposable (nonwoven)

Disposable (nonwoven)

  • made from regenerated cellulose, wood pulp, polyesters, synthetic polymer fibers or combinations
  • effectiveness of barrier varies with product
  • generally only those reinforced with plastic or polyethylene film are impermeable
  • convenient but usually more expensive (depends on labour costs) 

Opening packs

  • Sterile packs contain surgical drapes, instruments, gowns and gloves
  • Sterile packs are double wrapped in cloth to increase storage life
    • Only sterile 24 hours if single cloth wrap
    • Sterile 3 weeks if double cloth wrap
    • sterile as long as wrapping intact (no holes) if sealed in plastic
  • Opened by non-sterile person
  • Both wraps opened touching only outside so a sterile field is created
  • Extras are opened and tossed into center of sterile field without reaching over the field 
    Explanation:  Prevents bacteria and skin flakes from the person from falling on the sterile field contaminating it
  • Once opened, the peripheral 5 cm in contact with a nonsterile surface is considered contaminated as well as anything below the table edge

Draping site

For a surface to remain sterile, it must not be touched by a contaminated surface  

Protect your gloves - if they touch a contaminated surface they must be changed


    • fold them inside edges of a sterile drape when draping

    • otherwise keep gloves visible

  • Avoid shaking the drapes (harder to control edges and creates excess air currents)

  • Keep drapes above your waist (inside surgeon's sterile zone)

  • Don't reach over the table to drape the far side; walk to other side of table to place the drape (can contaminate gown or drape as lean over)

  • Place drapes where they will ultimately lie - do NOT move drape closer to the surgical field as bacteria and dirt from the haired region are pulled toward your sterile field  

“Ground” or “square” drapes

    • generally drapes are applied along each side of a square containing the proposed incision and the immediate surrounding area
    • isolates incision area from the unprepped areas
    • Drapes should be large enough to cover the animal and table

Slit drape (or laparotomy drape)

    • Second layer of drapes
    • Should provide an effective barrier to fluids (ie. treated with water repellent or plastic reinforced)
      • want to see water bead on surface
    • Slit in center that is placed over the proposed incision site
    • Covers the entire field with a single drape
  • additional drapes are applied as necessary to ensure the entire animal and table is covered by two layers of drapes

Draping table

  • All the instruments and supplies required for the procedure should be within easy reach
    • entire table should be covered
    • second layer should be waterproof
    • organized so instruments and supplies are quickly available


  1. Large instrument table
    • rolled close to the patient
    • organized so that instruments and supplies are within easy reach
  2. Mayo stand 
    • Small movable table that can be moved over surgical field to ensure easy access to instruments
    • useful for simple procedures with minimal instruments and supplies
    • draping
      • covered by “pillow case” to minimize contamination from underneath
      • second drape should be waterproof
      • covering towel gives stable surface

Sterile field

Surgical Image Table

  • peripheral 5 cm edge in contact with a non-sterile surface is considered contaminated because may have touched a nonsterile surface
  • anything below the table edges is considered contaminated as good chance may have had contact with a non-sterile surface or a person
  • If you can't see it → it should be considered contaminated