Patient Preparation: Clipping, Surgical Scrub, Draping, and Positioning

Patient preparation begins in the induction area, not the operating room. The goals are to remove hair and soil from the surgical site, apply an antiseptic that reduces the resident skin flora to a sub-pathogenic level, position the patient so the surgeon has unobstructed access, and drape to create a sterile barrier between the cleaned field and the rest of the patient. Every step is done outside the OR (or in a dedicated prep area) so that hair and skin debris do not contaminate the sterile field, the surgical suite, and the sterile team.

Clipping

Clip generously - the clip margin must extend well beyond the anticipated incision and any potential extension, drains, or additional port sites. A ventral midline celiotomy is clipped from 4-5 cm cranial to the xiphoid to the pubis, laterally to the mammary chain folds (or past them in deep-chested dogs), and around the prepuce and scrotum in male dogs (the prepuce is flushed and a clean purse-string suture or stay may be placed around it to prevent it from entering the incision). Orthopedic procedures clip circumferentially around the entire limb - not just the surgical site - from above the proximal joint to below the distal joint (for example, a stifle surgery is clipped from the mid-femur to the mid-tibia, circumferentially), because the limb will be manipulated intraoperatively and unclipped fur will contaminate the sterile field. A tail amputation is clipped from the base of the tail across the perianal area and up the dorsal and lateral pelvis.

Clip before scrub so that hair and clipper oil are removed by the scrub. Use a #40 blade for the main field and a #10 for fine finishing around delicate areas; vacuum or wipe the clipped hair away immediately. Lubricate clipper blades and let them cool between patients - hot blades burn thin skin (cats, rabbits). A common mistake is clipping too narrowly; if the surgeon needs to extend the incision or place a drain, an unclipped margin forces contamination.

Positioning

Positioning depends on the surgical approach:

Padding protects peripheral nerves (radial in forelimb, peroneal in hindlimb, brachial plexus) and bony prominences (olecranon, greater trochanter, humeral epicondyle, ischiatic tuberosity, lateral tarsus) from pressure necrosis. Limbs are tied with soft gauze or padded ties, never elastic tourniquet left in place long; ties are released periodically in long procedures to restore circulation. The head and neck are positioned to protect the endotracheal tube (kinking, dislodgement) and to avoid jugular compression, which raises intracranial pressure and impedes venous return.

Surgical Scrub

The surgical scrub reduces the bacterial burden on the patient's skin. Two antiseptics dominate veterinary practice:

• Chlorhexidine gluconate 2% or 4% - broad-spectrum, persistent activity (binds stratum corneum and remains active for 48 hours), not inactivated by blood or organic material. Safe for most species; dilute for cats and small mammals to reduce ototoxicity risk (rare but reported). Compatible with alcohol.
• Povidone-iodine 7.5% scrub with 70% isopropyl alcohol or povidone-iodine solution - broad-spectrum, fast onset, inactivated by blood and organic material (must be reapplied if contaminated), staining, can cause contact dermatitis with repeated use, and cats may develop thyroid changes with chronic iodine exposure. Alcohol speeds drying and adds a rapid bactericidal effect.

The scrub technique is the same regardless of agent:

1. Start at the incision site (cleanest skin).
2. Work from center to periphery - circular strokes, never crossing back over the clipped field once you have moved outward. Reaching back toward the center brings the dirtier peripheral skin flora back to the surgical site.
3. Repeat with fresh gauze or sponge - typically 5 minutes and at least 3-4 cycles of scrub, rinse (if using povidone-iodine scrub), scrub again. Chlorhexidine is usually applied and left to dry (no rinse) for sustained activity.
4. Allow to dry - never drape or incise through wet antiseptic. Wet chlorhexidine or iodine trapped under a drape can cause chemical burn and inactivates the drape's barrier. Air-dry or blot with sterile gauze.
5. Final paint - chlorhexidine solution or 70% alcohol applied as a single coat and allowed to dry before draping.

A VTNE-tested trap: alcohol alone is not a surgical antiseptic - it has no persistent activity and is inactivated by organic material. Povidone-iodine scrub (the sudsing form) is for the initial scrub; povidone-iodine solution (the paint) is for the final coat; the two are not interchangeable.

Draping

Draping creates the sterile barrier between the prepared field and the rest of the patient and team. Rules the technician must internalize:

• Square draping, not round - four drapes are placed, one on each side of the incision, forming a square (or rectangle) around the site. Round draping leaves gaps where contamination enters; square draping creates a defined sterile perimeter.
• Only sterile touches sterile - the drape is handled only by the gloved and gowned surgeon or scrub technician; the circulating technician hands the drape over without touching the sterile surface.
• Drape from the sterile side outward - place the near edge first, then the far edge (the surgeon reaches across the field without crossing over). Once a drape is laid, it cannot be adjusted - lifting a drape contaminates the underside, and repositioning drags bacteria across the prepared skin. If a drape is misplaced, discard it and apply a fresh one.
• Never reach over an unsterile area to place a drape - the surgeon stays within the sterile field; the circulating tech stands outside.
• Secure the corners - four towel clamps (or a sterile adhesive drape) secure the corners of the square. Towel clamps penetrate the skin and are considered part of the sterile field once placed.
• Fenestrated drape - the final drape has a fenestration (window) over the incision; the rest of the drape covers the patient. Once placed, the patient is fully draped and the sterile field is established.
• Breaches are addressed immediately - a drape that becomes wet has 'struck through' and is no longer a barrier (moisture wicks bacteria from underneath); reinforce with a fresh dry drape. A drape that slips is replaced, not pulled back into place.