Sutures are the stitches doctors, and especially surgeons, use to hold skin, organs, blood vessels and all other tissues of the human body together, after they have been severed in minor or major surgery.
Sutures are designed to help the healing of the body by closely opposing the two sides of a wound to minimize scar formation or to prevent leaking blood, like in vessels. They have to comply with several requirements to be effective. They must be strong (so they do not break), non-toxic and (to avoid adverse reactions in the body), and flexible (so they can be tied and knotted easily). In addition, they must lack the so called "wick effect", which means that sutures must not allow fluids to penetrate the body through them from outside, what could easily cause infections.
Absorbable sutures were originally made of the intestines of sheep, the so called catgut. The manufacturing process was similar to that of natural musical strings for violins and guitars, and also of natural strings for tennis raquets. Today, natural absorbable sutures are made primarily of bovine intestine. However, the major part of the absorbable sutures used are now made of synthetic fibers, like polyglycolic acid.
Non-absorbable sutures are made of materials which are not metabolized by the body, and are used therefore either on skin wound closure, where the sutures can be removed after a few weeks, or in some inner tissues in which absorbable sutures are not adequate. This is the case, for example, in the heart and in blood vessels, whose rhythmic movement requires a suture which stays longer than three weeks, to give the wound enough time to close. Other organs, like the bladder, contain fluids which make absorbable sutures disappear in only a few days, too early for the wound to heal. Inflammation caused by the foreign proten in absorbable sutures can amplify scarring, so if removable sutures are less antigenic it would represent a way to reduce scarring.
There are several materials used for non-absorbables sutures. The most common is a natural fiber, the silk, which undergoes a special manufacturing process to make it adequate for its use in surgery. Other absorbable sutures are made of artificial fibers, like polyester or nylon. Finally, there are also metal wires used in orthopedic surgery because of their strength and in some other tissues because of the metal's outstanding tolerance by the body.
