Introduction to Using a Scalpel
Scalpels are an important tool for performing surgical approaches and tissue dissections. However, if used incorrectly, scalpels pose a danger to both the patient and the surgical team. It is very important to learn how to handle a scalpel correctly, whether using it, handing it to someone, or changing the blade. In this module we will discuss how to safely arm, disarm, and pass a scalpel, as well as how to grip a scalpel and the methods of cutting with a scalpel blade. We will also examine the types of scalpel blades and handles that are commonly used in veterinary practice and their surgical applications.
Anatomy of a Scalpel Blade
- The spine of the scalpel blade is the unsharpened, rigid edge. Scalpel blades are generally made of hardened and tempered steel, stainless steel, or high carbon steel.
- The edge of the scalpel blade is the sharp, cutting surface. Scalpel blades are available in a variety of different styles. The main differences relate to the overall size of the blade or the shape of the cutting edge.
Types of Scalpel Blades
Scalpel blades come in a variety of sizes, commonly referred to by the blade number. Blades also vary by length and shape of the cutting edge, with each blade suited to different purposes.
- The No. 10 blade, with its large, curved cutting edge, is one of the more traditional blade shapes used in surgery. It is generally used for making large incisions in the skin and subcutaneous tissue, as well as cutting other soft tissue.
- The No. 11 blade is an elongated, triangular blade sharpened along the hypotenuse edge. It has a strong, pointed tip, making it ideal for stab incisions and precise, short cuts in shallow, recessed opening major blood vessels for catheter insertion, removing the mop ends of torn cruciate ligaments, and for meniscectomy.
- The No. 12 blade is a small, pointed, crecent-shaped blade sharpened along the inside edge of the curve. It is sometimes utilized as a suture cutter. Occasionally the No. 12 blade is used for disarticulating small joints, such as those between the metacarpels, metatarsals, and phalanges during digit amputation.
- The No. 15 blade has a small, curved cutting edge. It is one of the most popular blades in surgery because its shape is ideal for making short and precise incisions. It is utilized in a variety of surgical procedures, including the excision of small skin lesions, organ biopsy, and fine neurological applications.
- The No. 22 blade is a larger version of the No. 10 blade with a curved cutting edge and a flat unsharpened back edge. It is often used for creating large incisions through thick skin, and for soft tissue dissection in surgery.
Anatomy of a Scalpel Handle
The handle of the scalpel blade is the part of the instrument that is gripped by the surgeon. The handles are made such that both right- and left-handed individuals can use the same handle safely and effectively.
Types of Scalpel Handles
The standard scalpel handle used in surgery is the No. 3 size. The No. 3 features a short handle that is useful for making skin incisions and for cutting superficial tissues, such as the subcutaneous layer.
The No. 3L has a longer handle than the No. 3 making it suitable for incising in deep, remote areas such as the thoracic cavity.
Handing Off Scalpels
Keep in mind that safe handling of scalpels not only reduces sharps-related injuries, but also minimizes potential exposure to zoonotic pathogens.
- To hand off a scalpel, begin by grasping the surgical scalpel in the center of the handle with your dominant hand.
- Orient the blade facing away from your palm and away from the person to whom you want to hand the scalpel.
- Firmly place the scalpel handle in the outstretched hand of the person receiving the scalpel, but do not immediately withdraw your hand.
- Once he or she has a firm grasp of the handle, slowly remove your hand.
Areas of Concern
A common mistake when handing off scalpels is for the person receiving the scalpel to pull it away too soon.
To avoid injury, the person receiving the scalpel should grasp it and then wait until the other person’s hand is completely withdrawn before he or she pulls the scalpel away.
In the pen grip, the scalpel is grasped close to the blade between the tips of the thumb and the index finger, with the remaining handle resting on the web of the thumb, much like grasping a pen. In this grip, the motion comes predominately from the thumb with the index finger, allowing for precise cutting of tissue. To increase the accuracy of the fine cutting, you can also steady your hand by resting the ring and little fingers on the patient as you cut. The pen grip can also be “backhanded” by reversing the direction of the blade without changing the upper arm position.
Grasping the scalpel handle like a pen allows short, fine movements, using the muscles of the hand, with less contribution from muscles of the forearm. The pen grip is therefore most useful for making small, precise incisions.
In the pen grip, the blade edge is held at a 30- 40-degree angle to the tissue. In comparison to the other scalpel grips, this greater angle diminishes the cutting edge contact, limiting both depth and direction control. Thus, the pen grip is not ideal for creating long, straight skin incisions.
In the fingertip grip, the scalpel is held between the thumb and middle finger, while the index finger is places on the spine of the scalpel blade to apply downward pressure, much like grasping a butter knife. This grip is used primarily for making lo0ng skin incisions, using arm motion, rather than using the finger motion associated with the pencil grip.
The chief advantages of the fingertip grip are that it provides good depth and direction control. Because this grip maximizes the length of the blade that comes into contact with the tissue, any changes in blade pressure are distributed over a greater length. This delivers less pressure to each increment of tissue and allows for greater security of depth control. Additionally, the great the length of tissue in contact with the scalpel, the more the walls of the incision resist minute or sudden changes in direction, allowing for smoother, straighter incisions. The combined advantages of both depth and direction control make the fingertip grip well suited to creating long incisions.
The fingertip grip does not allow for precise blade cuts, so it is not used when delicate, precise scalpel cuts are required, such as in ophthalmic and vascular procedures.
In the palm grip, the middle, ring, and little fingers are wrapped around the scalpel handle, with the thumb anchoring the handle from the opposite side. The index finger is rested on top of the scalpel handle and force is applied to the handle with forearm pressure. The wrist is held straight.
The palm grip is the strongest, most secure way to grasp a scalpel handle, but it Is rarely indicated for most surgery applications. Its main surgical use is when great pressure is needed to cut through very dense tissue. The most common use for the palm grip is to cut open cadavers during a necropsy examination.
In the palm grip, the grasp is held well away from the cutting blade edge and forearm pressure is used to exert force, resulting in little control over blade pressure. This lack of pressure control means that the palm grip should not be used for surgeries that require accuracy and control.
To incise tissue with a press cut, begin by grasping the scalpel in a pen grip. With the blade positioned over the tissue, slowly increase downward pressure on the blade tip. When the bursting strength threshold of the tissue is exceeded, the blade will suddenly pop through the targeted tissue. In press cutting, the direction of the pressure exerted by the surgeon is the same as the direction of the blade motion as it cuts through the tissue. A stab incision is a classic example of a press cut.
With press cutting, the wound is well controlled in both length and direction, as the length of the wound is exactly the width of the scalpel blade and the direction is in line with the plane of the blade. Press cutting Is useful for making stab incisions in hollow structures. Once the wall is penetrated, the hollow space below the blade provides space for the blade to decelerate and stop without damaging deeper structures. The press cut is often used in surgery to drain abscesses and to open the bladder, stomach, and intestines.
The usefulness of press cutting in surgery is limited by the all-or-none quality of tissue depth penetration. It is important to realize that depth control is not precise with press cutting; the pressure needed to overcome starting friction is greater than the pressure needed to continue the path of the scalpel one the tissue begins to part. Additionally, the outer layer of tissue generally has greater bursting thresholds than deeper layers, which further accentuates this depth control problem. To mitigate this problem, position the sharp edge facing your palm, and use your index finger as a bumper to expose only a limited amount of the blade tip. Then rest your knife hand against the patient during the stab incision to limit the depth of the blade plunge.
To perform a slide cut, the scalpel is generally grasped in the fingertip grip. The cut is made by sliding the blade on its cutting edge, while exerting a sub-bursting pressure on the tissue. In the slide cut, the cutting motion is at a right angle to the direction of the scalpel pressure. The depth of the incision is determined by the amount of pressure exerted, the length of the blade distributing that pressure, and the resistance to cutting of the tissue being incised. Light pressure, combined with an increased blade surface area to skin ratio, results in a more superficial cut.
The slide cut is the most applicable cut for most scalpel applications. In particular, it is well suited to skin incisions because it allows accurate depth control and precise direction and length control.
The main limitation of the slide cut is that it does not allow for short, deep incisions in tissue.
To perform a scrape cut, the scalpel can be grasped in either a pen or fingertip grip. When scraping delicate tissue, such as an anal-sac, the pen grip is generally preferred. The cutting motion in the scrape cut involves exerting sub-bursting pressure while moving the scalpel perpendicular to the edge of the blade and the direction of the pressure. Scrape cutting is exactly the same motion used when shaving hair with a razor blade.
Scrape cutting is a precise way to separate layers of tissue without cutting the deeper layers beneath the blade, knows as button holing. Button holing can easily occur with push cutting, and sometimes with slide cutting. Scrape cutting is used for developing pouches for devices and the separation of fascia planes in reconstructive surgery; for example, when separating tissue from fascia during mastectomy. Scrape cutting is also used when separating muscle attachments to the anal sac without rupturing the deeper, thin sac wall during anal sacculectomy. The scraping motion also provides some security from perforation of surfaces when releasing adhesions, and in scarifying the serosal surfaces of viscera for purposefully creating an adhesion, as in colopexies for recurrent rectal prolapse.
Scrape cutting is not an efficient method for incising tissue. This cutting technique is also more traumatic to tissues than sharp dissection with a slide cut.
Hot To Incise Skin
A good-quality skin incision requires careful planning and a skilled execution. Obtaining the desired outcome requires an understanding o fall the components involved in making an incision, as well as practice putting all of these elements together.
- Before beginning any incision, carefully plan your surgical approach. With the patient in a neutral position and the skin undistorted, establish the starting and stopping landmarks of your incision. As you advance your blade along your incision, be careful not to distort the skin, as this can lead to accidental incisions over vital structures or difficulty reaching or identifying a muscle or fascia plane for deeper dissection.
Surgeons often plan their incision using visible landmarks, such as the umbilicus, or palpable bony structures like the greater tubercle or xiphoid cartilage. Keep in mind that skin is pliable and might be inadvertently shifted out of neutral position, especially in loose skinned patients. When planning a complex approach, such as a curvilinear incision, a sterile marking pen is often helpful. Marking the proposed incision for a complex approach, like the craniolateral approach to the hip, helps to prevent skin distortion and abrupt angles.
- Using the slide cut technique, incise the skin’s full thickness in one smooth stroke. Only on rare occasion do you need to stop the skin incision before completion, as when a large sub-dermal vessel is traversed and is found to bleed excessively.
Often the novice surgeon errs towards a stop and go approach, resulting in short, choppy incisions that do not penetrate full thickness of skin. The problem with this technique is that the surgeon must then try to retrace the first incision accurately, or the second incision will isolate and devitalize an island of skin. Devitalized islands should be avoided as they lead to wound complications after closure. To avoid such problems, strive to complete the entire incision in one smooth stroke, before the blade is ever pulled from the skin incision.
- To prevent bunching and to control the direction of the scalpel, use your non-dominant hand to pull the skin away from the direction of the blade, while using your thumb and index finger to place tension perpendicular to the blade. When making long incisions, the assisting hand might need to advance 3 to 4 times to maintain the appropriate skin tension. When pausing the incision to advance the assisting hand, do not remove the blade from the tissue.
Redundant skin that bunches up in the path of the blade results in a jagged incision. It tension is not maintained during an incision, redundant skin will catch on the blade and this might cause the blade to skip, resulting in a serrated incision. Be careful not to advance the assisting hand past the leading edge of the blade. Removing and reinserting the blade makes it difficult to stay on the same track, resulting in jogs in the incision. In most cases, the surgeon should be the only person touching and stretching the skin during skin incising. If an assistant is used to place tension on one side of the incision and the surgeon on the other, neither person has any idea how much tension is being exerted by the other. If ne side is under more tension, the skin incision will be created as a bow toward the side under less tension.
- During the slide cut, watch as the edges of the skin begin to part. Blade pressure should be increased until the skin edges part about 1.5 to 2 centimeters. This ideal pressure is then maintained throughout the length of the incision. Ideally, you should cut the skin just beyond the hypodermis, but not into the deeper subcutaneous tissue where larger blood vessels can be damaged. If the skin incision is created this way, larger subcutaneous vessels can be identified and ligated, or sealed, before they are incised. This ensures a cleaner, dryer incision field, facilitating the identification of deeper tissue layers for more accurate dissection.
Ideally, skin should be incised full thickness into the hypodermis throughout the incision with the first pass of the blade. Surgeons use the distance of skin separation during slide cutting to assess and control the depth of their incisions. Keep in mind that a thin skinned patient, little pressure will be needed to create a 1.5 centimeter wide, full thickness incision. However, when incising thicker skinned patients, significantly more pressure will be required. A common error made by novice surgeons is to exert insufficient pressure, resulting in partial skin penetration. If the skin is only partially cut during the incision, a V shaped groove will appear and the skin edges will not separate. This V often fills with blood, making it difficult to observe the apex of the V. The second stroke of the scalpel, required to complete the skin transection, will then miss the apex of the V, creating a jagged tissue cut. To avoid this mistake, always monitor the edges of the skin incision to ensure that the optimal amount of pressure is being applied to the scalpel.
- One of the keys to creating a good incision is to watch where the blade has been, rather than focusing solely on where the blade is going. Although this may initially seem counter-intuitive, whether you are making a straight or a curved incision, pay attention to the segment that has already been cut.
Following this principle allows you to monitor the separation of the skin edges so that you can assess and adjust the amount of pressure needed to create an incision at the proper depth. Watching where the scalpel has been, while remaining cognizant of where it is going, also helps you keep your incision on the desired path.
- When making a skin incision, always make the cut perpendicular to the surface of the skin.
Novice surgeons have a tendency to keep the blade perpendicular to the floor instead of perpendicular to the surface of the skin, resulting in an angled incision. When the skin is cut on an angle, the slanted cut surfaces tend to override one another during the skin closure. This overridden edge is unsightly and might increase scar formation. It can also be a source of irritation to the patient, leading to self-excoriation.
- Once the skin incision has been completed, bleeding from transected vessels should be controlled. If possible, the next incision through the fat should be made directly in line with the skin incision.
Controlling the bleeding allows for better visualization of the underlying subcutaneous fat. The alignment of tissue layers relieves tension on the sutures, promoting accurate wound closure and viable skin edges.