A scalpel, lancet, or bistoury is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, podiatry and various arts and crafts (either called a hobby knife or an X-acto knife). Scalpels may be single-use disposable or re-usable. Re-usable scalpels can have permanently attached blades that can be sharpened or, more commonly, removable single-use blades. Disposable scalpels usually have a plastic handle with an extensible blade (like a utility knife) and are used once, then the entire instrument is discarded. Scalpel blades are usually individually packed in sterile pouches but are also offered non-sterile. Double-edged scalpels are referred to as "lancets".
Scalpel blades are usually made of hardened and tempered steel, stainless steel, or high carbon steel; in addition, titanium, ceramic, diamond and even obsidian knives are not uncommon. For example, when performing surgery under MRI guidance, steel blades are unusable (the blades would be drawn to the magnets and would also cause image artifacts). Historically, the preferred material for surgical scalpels was silver. Scalpel blades are also offered by some manufacturers with a zirconium nitride–coated edge to improve sharpness and edge retention. Others manufacture blades that are polymer-coated to enhance lubricity during a cut. Alternatives to scalpels in surgical applications include electrocautery and lasers.
Surgical scalpels
Surgical scalpels consist of two parts, a blade and a handle. The handles are often reusable, with the blades being replaceable. In medical applications, each blade is only used once (sometimes just for a single, small cut).
The handle is also known as a "B.P. handle", named after Charles Russell Bard and Morgan Parker, founders of the Bard-Parker Company. Morgan Parker patented the 2-piece scalpel design in 1915 and Bard-Parker developed a method of cold sterilization that would not dull the blades, as did the heat-based method that was previously used.
The handle of medical scalpels come in several basic types. The first is a flat handle used in the #3 and #4 handles. The #7 handle is more like a long writing pen, rounded at the front and flat at the back. A #4 handle is larger than a #3. #5 handles are also common, and are round, with a patterning to ensure a non-slip grip. Blades are manufactured with a corresponding fitment size so that they fit on only one size handle. The following table of blades is incomplete and some blades listed may work with handles not specified here.
A lancet has a double-edged blade and a pointed end for making small incisions or drainage punctures.
Types of blades
Gripping a medical scalpel
Palmar grip
Also called the "dinner knife" grip. The handle is held with the second through fourth fingers and secured along the base of the thumb, with the index finger extended along the top rear of the blade and the thumb along the side of the handle. This grip is best for initial incisions and larger cuts.
Pencil grip
Best used for more accurate cuts with smaller blades (e.g. #15) and the #7 handle. The scalpel is held with the tips of the first and second fingers and the tip of the thumb with the handle resting on the fleshy base of the index finger and thumb. Care should be taken not to allow the handle to rest too far along the index finger as this promotes an unstable grip and cramped fingers.
Graphic design and arts and crafts blades
Graphical and model-making scalpels tend to have round handles, with textured grips (either knurled metal or soft plastic). The blade is usually flat and straight, allowing it to be run easily against a straightedge to produce straight cuts.
There are many kinds of graphic arts blades; the most common around the graphic design studio is the #11 blade which is very similar to a #11 surgical blade (q.v.). Other blade shapes are used for wood carving, cutting leather and heavy fabric, etc.