Surgical Instruments: Identification and Use for Veterinary Technicians

Introduction

Surgical instruments are the technician's daily vocabulary in the operating room. You build the packs, set the Mayo stand, pass what the surgeon asks for and count everything back at the end. A basic pack usually holds towel clamps, a scalpel handle and blade, a needle holder, thumb forceps, suture scissors, tissue scissors and a few hemostatic forceps, and it is enough for an ovariohysterectomy or a wound exploration.⁶

This guide teaches you to name an instrument from what you can see: rings, ratchet, jaw pattern, blades and tips. It covers scalpels, scissors, thumb and tissue forceps, hemostats, needle holders, towel clamps, retractors, basic orthopedic tools and the spay hook, with the common mix-ups the VTNE likes to test.

Key facts

How the VTNE tests this

• Identify the instrument from a description of its jaws, tips, rings or blades, or choose the one the surgeon has asked for. Domain 2 Task B (prepare instruments and supplies for the surgical team); K17 (surgical equipment, instruments and supplies).²²
• Match the instrument to the tissue: which scissors for linea alba, which forceps for bowel, which hemostat for a pedicle. Domain 2 Task D (function as a sterile surgical technician).²²
• Spot misuse and damage: tissue scissors used on suture, a needle holder that lets the needle rotate, a towel clamp moved after placement. Domain 2 Task H (maintain instruments); K19 (safety considerations for surgical instruments).²²
• Handle sharps safely when loading, passing and disposing of scalpel blades. K19.²²

Core concepts

Parts of a ringed instrument

Most hemostats and needle holders have ring handles and a ratchet locking mechanism.⁴⁵ Learn the parts from the hand end forward:

• Rings: the finger holes. The surgeon places the thumb and ring finger in them, using only the fingertips.⁴
• Ratchet: interlocking teeth near the rings that hold the jaws closed without hand pressure. This is what lets a hemostat stay on a vessel while a ligature is tied.¹²
• Box lock: the joint where the two halves cross. The index finger rests here for tip control.⁴ Box locks and serrations trap blood and tissue, so they need the most cleaning attention.¹⁸
• Jaws: the working end. Their length, width and serration pattern identify the instrument.

Scissors also have rings, but no ratchet. Thumb forceps have no rings and no lock at all; they are tweezer-like instruments held between the thumb and index finger with a pencil grip.³¹⁰

Cutting instruments: scalpels

The scalpel is the least traumatic way to divide tissue.¹ Reusable handles with single-use blades are the norm in veterinary practice. The No. 3 handle is used more often than the No. 4. The No. 7 handle is long and thin and is used for more delicate incisions. Small Beaver handles hold miniature blades for eye surgery and tight spaces such as joints.⁷

Blades with a curved cutting edge (10, 15, 20 and the larger numbers) are called belly blades. Their sharpest point is the apex of the curve, which is the part that does the cutting.¹⁶ Common blades:

• No. 10: large incisions through skin and subcutaneous tissue; the most common blade in veterinary practice.⁷¹⁶
• No. 11: triangular with a sharp point, the stab blade.¹⁶ It makes stab incisions, for example the small skin incision before a bone marrow aspirate needle is inserted.¹⁷
• No. 12: curved crescent shape, often used to remove sutures.¹⁶
• No. 15: the smallest belly blade, used where short, precise incisions are needed.¹⁶
• No. 20: fits the No. 4 handle; for larger incisions through thicker tissue and for soft tissue in larger animals.⁷¹⁶

Three grips come up in surgery. The fingertip grip is the most common and gives the best control for long incisions. The palm grip is the strongest. The pencil grip limits blade contact and suits short, precise cuts and controlled stab entry into the abdomen or a hollow organ.¹⁸

Cutting instruments: scissors

Scissors are classified by their tips (sharp-sharp, blunt-blunt, sharp-blunt), their blade shape (straight or curved) and their cutting edge (plain or serrated). Straight blades give more mechanical advantage for thick tissue. Curved blades give better reach and a better view of the tips.²

• Mayo: sturdy, for heavy tissue such as linea alba and thick fascia. Memory tip: short name, short handle.²
• Metzenbaum: finer, for delicate tissue and blunt dissection. Memory tip: long name, long handle.² Guelph's surgery text describes a long handle to blade ratio and use on thin, soft tissue such as bowel and fat.⁹
• Operating or suture scissors (often sharp-blunt): cheaper scissors kept for suture and other materials, never tissue, so the tissue scissors stay sharp.²⁹
• Suture removal scissors: a notch in one blade hooks the suture loop without lifting the skin too far.⁹
• Lister bandage scissors: a large lower blade with a blunt nodule at its tip slides under a bandage without cutting skin.⁹
• Iris and tenotomy scissors: small, delicate scissors used mostly in eye surgery.⁹

Grasping instruments: thumb forceps

Thumb forceps do not lock. Smooth (toothless) forceps seem gentler, but they need more pressure to hold tissue and can crush it more than toothed forceps.¹⁰

• Adson: fine tips on broad handles and a 2 x 1 tooth pattern (two teeth on one tip, one on the other). The smaller size suits small animal work.³¹⁰
• Brown-Adson: many fine intermeshing teeth in rows; a secure grip on tissue and on small needles.³¹⁰
• Rat-tooth: larger interdigitating teeth for skin and dense tissue such as fascia; too coarse for delicate tissue.³¹⁰
• DeBakey: fine longitudinal striations; an atraumatic grip on vessels and fragile tissue, also popular for bowel and bladder.¹⁰

Ringed tissue forceps

Allis forceps have interlocking teeth, ring handles and a ratchet. They are traumatic, so they are kept for fascia or tissue that is being removed.³¹¹ Babcock forceps have longitudinal grooves instead of teeth. They are less traumatic than Allis but hold less securely.³ Babcocks were designed for intestine, but the Guelph text advises against using them on bowel; Doyen forceps are the bowel clamp.¹¹ Sponge forceps hold gauze during the final skin prep so the surgeon's gloves stay sterile.²³

Hemostatic forceps

Hemostats crush a bleeding vessel, which starts clotting, and the ratchet holds them shut while a ligature is placed. Curved tips are usually preferred because the tip is easier to see.⁴¹² Read the jaws (Figure 2):

• Halsted mosquito: the smallest of these four. Transverse serrations along the whole jaw. For pinpoint bleeders, not for large pedicles.⁴¹²
• Kelly: larger than mosquito. Transverse serrations on the distal half of the jaw only. Small to medium vessels.¹²
• Crile: also larger than mosquito, but transverse serrations run the full jaw length. Small to medium vessels.¹²
• Rochester-Carmalt: large crushing forceps for pedicles and stumps. Longitudinal serrations with cross striations at the tip. The lengthwise grooves let the clamp slide off easily as the ligature is tightened.⁴¹²

Needle holders

Needle holders hold the needle and the suture ends. Their jaws are wider and shorter than hemostat jaws, and better models have tungsten carbide inserts with fine cross striations.⁵¹³

• Mayo-Hegar: heavy, with short strong jaws and no cutting blade.⁵¹³
• Olsen-Hegar: scissor blades sit just behind the jaws, so a surgeon working alone can suture and cut with one instrument. The risk is cutting the suture by accident.⁵¹³
• Mathieu: a ratchet at the proximal (hand) end of the handles locks and unlocks when the handles are squeezed in a palm grip.¹³
• Castroviejo: small, spring and latch lock, held with a pencil grip for microvascular and eye surgery.⁵¹³

Towel clamps

Backhaus clamps have sharp points and are the usual clamp for holding drapes to the skin. Roeder clamps look similar but have ball stops that limit how deep they go. Lorna clamps do not perforate, so they hold suction lines and cautery cords to the drape.¹⁴

Retractors

Hand-held retractors need someone to hold them. Self-retaining retractors lock open with a ratchet or bolt.¹⁵

• Senn (hand-held): three sharp curved prongs at one end, a right-angle blade at the other; for skin and superficial muscle.¹⁵
• Army-Navy (hand-held): flat, with a 90-degree blade at each end; for large muscle groups.¹⁵
• Gelpi (self-retaining): curved arms with a single sharp angled tip on each; ratchet.¹⁵
• Weitlaner (self-retaining): curved arms with several sharp or blunt prongs; ratchet.¹⁵
• Balfour (self-retaining): holds the abdominal wall open, usually with a central blade.¹⁵
• Finochietto (self-retaining): a rib spreader for chest surgery, opened by turning a handle.¹⁵

Orthopedic basics and the spay hook

• Periosteal elevator: lifts muscle off bone. The Freer is a double-ended example.¹⁵
• Rongeur: forceps with sharp-edged, cupped jaws that bite away bone. Double-action models need less hand force.¹⁵
• Bone curette (Spratt, Volkman): a sharp-edged cup on a shaft for collecting bone graft and debriding soft or bony tissue.¹⁵
• Jacobs chuck and key: inserts pins and Kirschner wires by hand.¹⁵
• Osteotome and mallet: the osteotome is beveled on both sides (a chisel on one) and is struck with a mallet.¹⁵
• Spay hook (Snook or Covault): a long, thin instrument with a blunt hook that retrieves a uterine horn through a small incision.¹⁵

Procedure: setting up and checking instruments

Your role as the technician: build and check the pack before surgery, hand the right instrument during surgery, and keep sharps under control.

1. Read the pack list. A basic pack holds towel clamps, a scalpel handle and blade, a needle holder, thumb forceps, suture scissors, tissue scissors and hemostats (usually some mosquitoes, a few Criles and perhaps Carmalts).⁶
2. Check hemostats and other ringed clamps. Tips meet, jaws line up and the ratchet holds when closed.⁴¹²
3. Check needle holders. Clamp a needle of the right size and see whether it can rotate. If it can, the jaws need repair.¹³
4. Check every instrument for cleanliness, alignment, sharpness, cracks, rust and pitting. Do not pack a damaged instrument.¹⁸
5. Pack hinged instruments open, with the ratchets unlocked, so steam reaches every surface. Do not overload the pack, and include a sterilization indicator.¹⁸
6. During surgery, keep tissue scissors for tissue. Hand suture scissors when the surgeon asks to cut suture.²⁹
7. Towel clamps stay where they are placed. If a drape must move, use a new clamp, because the tips are contaminated once they have gone through the drape and skin.¹⁴
8. Count and clear sharps. Put used blades and other contaminated sharps straight into a closable, puncture-resistant, leakproof sharps container, and never put your hand into the container.²⁰²¹

Sources: University of Guelph Veterinary Surgery Online (scalpels, scissors); WCVM VSAC Lab 1 (scissors); World Precision Instruments blade guide.²⁷⁹¹⁶

Sources: University of Guelph Veterinary Surgery Online (forceps, needle holders, towel clamps, other instruments); WCVM VSAC Lab 1.^{345101112131415}

Flowchart: identify the instrument

Work through the questions from the handle end. Each yes or no narrows the choice, and the last step sends you to the jaw patterns in Figure 2.

Species differences

• Dogs and cats: the No. 3 handle with a No. 10 or No. 15 blade covers most incisions.⁷¹⁶ Adson forceps are sized for small animals.³ A spay hook lets the surgeon retrieve a uterine horn during an ovariohysterectomy through a relatively small incision.¹⁵
• Horses and food animals: the No. 4 handle and No. 20 blade suit larger incisions in thicker tissue and soft tissue work in larger animals.⁷¹⁶ An emasculator crushes and cuts the spermatic cord in open castration. Its crushing ridges sit on the "horse side" of the cutting edge, the side toward the animal, so the stump left in the patient is the crushed part.¹⁹ Gigli wire is a grooved single strand that cuts bone; embryotomy wire is braided from several fine strands.¹⁵
• Eye surgery and fine work: Beaver handles with miniature blades (eye surgery and tight spaces such as joints), iris and tenotomy scissors (eye surgery) and Castroviejo needle holders (microvascular and eye surgery) are the fine instruments to know.⁷⁹¹³

Safety, legal and client education

• Sharps rules. The OSHA bloodborne pathogens standard is written for human blood and other potentially infectious materials, so it generally does not cover animal blood. The American Veterinary Medical Association (AVMA) still recommends voluntary compliance in veterinary practice.²¹ Under that standard, scalpels are listed as contaminated sharps, and contaminated sharps go immediately or as soon as feasible into closable, puncture-resistant containers that are leakproof on the sides and bottom and labeled or color-coded.²⁰
• Reusable sharps. Under the same standard, contaminated reusable sharps wait in puncture-resistant, labeled, leakproof containers until reprocessed, and must not be handled in a way that makes staff reach into the container by hand.²⁰
• Passing. Avoid passing sharps hand to hand where you can, keep needles pointed away, and use safety-engineered devices when available.²¹
• Instrument life. Dried blood in box locks and serrations leads to corrosion and stiff joints. Rinse at point of use, clean with soft brushes, dry, then lubricate hinged instruments with instrument milk.¹⁸
• Client education. At a suture removal visit, you can explain that suture removal scissors have a notch that hooks each loop, so the skin is barely lifted while the suture is cut.⁹

Common mistakes and exam traps

Quick review

1. No. 3 handle: blades 10, 11, 12, 15. No. 4 handle: blades 20 to 23.⁷
2. No. 10 is the most used blade; No. 11 stabs; No. 12 removes sutures; No. 15 is small and precise.⁷¹⁶
3. Mayo cuts heavy tissue; Metzenbaum cuts delicate tissue; suture scissors cut suture.²
4. Adson 2 x 1 teeth; Brown-Adson rows of fine teeth; DeBakey longitudinal grooves.³¹⁰
5. Allis has teeth and is traumatic; Babcock has grooves and is gentler.³
6. Mosquito and Crile: transverse grooves full length. Kelly: distal half only.¹²
7. Rochester-Carmalt: longitudinal grooves, cross-hatched tip, for pedicles.¹²
8. Olsen-Hegar has scissor blades; Mayo-Hegar does not.¹³
9. Backhaus clamps pierce; Lorna clamps do not.¹⁴
10. Gelpi, Weitlaner, Balfour and Finochietto are self-retaining; Senn and Army-Navy are hand-held.¹⁵
11. Rongeur bites bone, periosteal elevator lifts muscle, Jacobs chuck drives pins.¹⁵
12. Pack hinged instruments open; used blades go straight into a sharps container.¹⁸²⁰