A lancet is a double-edged cutting tool that is also known as a scalpel. It is commonly used as a surgical instrument and dissection tool because of its extremely fine and sharp cutting surface. Students may use lancets for the dissection of small animals, such as frogs, fetal pigs, and cats, during the study of biology. Another type of lancet is used in the practice of arts and crafts, and is called a hobby knife. Of note is the fact that only a double-edged scalpel or hobby knife is referred to as a lancet.
Medical knives like lancets are generally made from 440C stainless steel, although they can be made from other materials. For example, stainless steel instruments cannot be used in conjunction with a magnetic resonance imaging (MRI) machine because the magnets would attract the steel. Other materials used for lancets include diamond, titanium, obsidian, and ceramic. Obsidian is a volcanic rock and bladed instruments made from obsidian are significantly sharper than those made from steel. In modern medicine, a laser scalpel is sometimes used in place of a lancet.
Scalpels and lancets were used as early as ancient Egypt and ancient Rome. While the ancient Egyptians used bladed instruments with sharpened obsidian to make incisions for the embalming of the deceased, ancient Romans used them as surgical instruments. The scalpels used in medicine by the ancient Romans were made from bronze, steel, or both.
Reusable lancets are sterilized in between uses when used as a medical device; disposable lancets may be used once and then discarded. Alternatively, disposable lancets may have a reusable handle with a replaceable blade. A blood lancet is a small bladed instrument often used by diabetics to draw blood for glucose testing. Although it is different from a scalpel, a blood lancet is frequently referred to simply as a lancet. Blood lancets are generally used only once before being discarded.
Safety is always a concern when dealing with medical knives. Although modern times have seen an increase in the manufacture of safety lancets, studies have shown that there is actually an increased incidence of injury associated with them compared to traditional scalpels. As with any type of sharp implement, using them safely is the responsibility of the user. The same is true with hobby knives since their blades are extremely sharp — just like those of medical knives. Disposable lancets typically should be discarded in a plastic container specifically made for that purpose to prevent injury and contamination.