A suture, commonly known as a stitch, is a specialized medical device used by surgeons and clinicians to hold body tissues together after an injury or a surgical incision. The primary function of this material is to approximate the edges of a wound, providing mechanical support until the body’s own healing processes can permanently fuse the tissue layers. Modern medicine relies on highly engineered materials tailored to specific biological needs and wound types.
The Fundamental Difference: Absorbable versus Non-Absorbable
The most fundamental distinction between different types of suture material is whether the body can naturally break it down over time. This classification separates them into two main categories: absorbable and non-absorbable materials. The choice between these two determines whether the stitches will require a separate procedure for removal or whether they will simply vanish.
Absorbable sutures are designed to lose their tensile strength and eventually disappear completely within the body. This process is achieved through hydrolysis, where water molecules interact with the suture material to break its chemical bonds. Because they provide temporary support, these sutures are used for internal wounds or deep tissue layers, eliminating the need for a second intervention.
Conversely, non-absorbable sutures are made of materials that the body’s enzymes cannot digest or break down. These materials are intended to remain in the tissue permanently or until a clinician physically removes them. They are chosen for areas that require long-term strength or prolonged support, such as in high-tension areas or for the repair of certain cardiovascular structures.
Non-absorbable materials are also the standard for most external skin closures that need to be removed after the initial healing period. The permanent nature of the material ensures the wound edges are held securely until the underlying tissue is strong enough.
Material Composition: Natural and Synthetic Sources
The threads used for stitches are derived from either natural biological sources or complex synthetic polymers. Historically, natural materials were the only option, but synthetic materials now dominate due to their consistency and predictable performance.
One of the oldest natural materials is surgical gut, often called catgut, derived from the purified collagen of sheep or cattle intestines. This absorbable material relies on the body’s enzymatic activity for breakdown, which can lead to a variable absorption rate. Silk is another natural material, non-absorbable and historically prized for its handling, though it is now less common due to higher tissue reactivity compared to synthetics.
Synthetic sutures have become the preferred standard across most surgical disciplines. Absorbable synthetics include Polyglycolic acid (PGA), Polydioxanone (PDO), and Polyglactin 910. These materials offer a controlled absorption profile through hydrolysis, allowing surgeons to select a thread that maintains its strength for a specific duration, such as 10 to 60 days.
Non-absorbable synthetic materials are frequently monofilaments, meaning they are a single strand, and include polypropylene, nylon (polyamide), and polyester. Polypropylene is highly valued for its inertness, meaning it provokes minimal reaction from surrounding tissue, making it a suitable choice for permanent implants or in contaminated wounds. Nylon is a strong, flexible material commonly used for skin closure, where its single-strand structure helps minimize the risk of bacterial adherence.
Selecting the Right Suture for the Wound
A surgeon’s choice of suture material is based on several factors unique to the patient and the wound location. The required tensile strength is a primary consideration; a high-stress area like an abdominal wall closure needs a much stronger thread than a delicate eyelid repair. The tissue’s natural healing rate also dictates selection, as slow-healing tissues require a suture that retains its strength for a longer period.
The location of the wound heavily influences the choice due to cosmetic and functional concerns. For instance, a monofilament nylon or polypropylene might be chosen for the face because its smooth, single strand structure passes through tissue with minimal trauma, promoting a better cosmetic outcome. Conversely, a braided suture, which consists of multiple woven filaments, offers superior knot security and handling, making a braided absorbable material like Polyglactin 910 a good choice for internal layers.
The potential for infection is another factor, as braided materials have a larger surface area where bacteria can harbor. In contaminated wounds or in patients with a high infection risk, a monofilament material is preferred because its smooth surface is less likely to harbor microorganisms. The surgeon must balance the need for strength and secure knotting with minimal tissue reaction and low infection risk.
Managing Stitches: Removal and Care
Once the wound is closed, patient care shifts to managing the stitches until the tissue is sufficiently healed. For external, non-absorbable sutures, removal is a necessary step that typically occurs between 5 and 14 days after placement, with the exact timing depending on the body location. Stitches on the face, which has a good blood supply and heals quickly, are often removed within five to seven days to minimize scarring.
Stitches placed over joints or on the back, which are subjected to higher tension and slower healing, may be left in place for up to 14 days. Basic wound care is paramount during this period, involving keeping the area clean and dry to prevent infection. The patient should follow specific instructions regarding water contact and how to gently clean the site.
If absorbable sutures were used internally or just beneath the skin, the patient may notice a subtle, localized reaction as the material begins to break down. This is the body’s natural response to the absorption process, which should not be confused with an infection unless accompanied by signs like increasing redness or pus.