A suture, commonly known as a stitch, is a medical device used to hold severed or incised body tissues together following an injury or surgery. This thread-like material approximates the wound edges, allowing the body’s natural healing processes to close the gap. The primary function of a suture is to provide temporary support and tensile strength while new tissue regenerates beneath the surface. Skin can grow over stitches; this is a known biological consequence of the healing process. While generally manageable, this overgrowth can complicate the removal of certain types of sutures, making it important to understand the underlying mechanisms and what signs require medical attention.
The Mechanism of Skin Overgrowth
The phenomenon of skin growing over a stitch is a direct result of the body’s highly efficient process of wound closure, known as re-epithelialization. The epidermis, the skin’s outermost layer, is designed to quickly cover any breach in the body’s barrier to prevent infection. When a wound is closed with sutures, epithelial cells (keratinocytes) at the edges activate, flatten, and begin migrating across the open surface. These cells move as a cohesive sheet over the underlying tissue to restore the protective layer.
If a non-absorbable suture is left in place longer than recommended, the rapidly migrating epithelial cells encounter the suture material and continue to grow over it, covering the small exposed loops. This biological drive to close the wound is strong enough that the skin seals itself around the foreign thread, effectively embedding the stitch.
The timing of this migration dictates strict removal schedules. Sutures on the face, where wounds heal quickly, are typically removed in 5 to 7 days to prevent overgrowth and reduce scarring. Areas like the lower extremities or joints, which endure higher tension and heal more slowly, may require sutures to remain in place for 14 to 21 days. Leaving a suture in beyond the optimal time increases the likelihood of overgrowth, which can result in permanent “railroad track” marks on the skin.
Distinguishing Absorbable and Non-Absorbable Stitches
The implication of skin overgrowth depends entirely on the type of material used for the stitch, categorized as either absorbable or non-absorbable. Absorbable sutures are designed to lose their tensile strength and break down within the body over a period of weeks to months. These are often used for internal tissues or for closing the deeper layers of a wound, meaning they never require manual removal.
If the skin grows over an absorbable stitch, it is not a concern because the material will eventually dissolve completely. The body degrades and clears this material, so the embedded thread disappears over time. Occasionally, a small piece of the dissolving suture may push its way out of the skin, which is a common and minor occurrence.
Non-absorbable sutures, made from materials like nylon or polypropylene, must be manually removed once the wound has achieved sufficient strength. If the skin grows over a non-absorbable stitch, the removal process becomes more complicated. A medical provider may need to gently probe or apply light pressure to expose the buried loop before it can be cut and pulled out. This complication is why timely suture removal is emphasized.
Signs of Trapped Stitches and When to Seek Medical Help
When a non-absorbable stitch becomes trapped beneath a new layer of skin, the main concern shifts from removal difficulty to the risk of foreign body reaction or infection. The body views the trapped suture material as an invader, sometimes attempting to push it out or wall it off. This reaction can manifest as a small, firm, pimple-like bump or a localized immune response called a suture granuloma.
A more serious complication is an infection, which requires prompt medical evaluation. Signs of a developing infection include increasing redness around the wound that spreads outward, noticeable pain or tenderness, and a sensation of warmth. The presence of pus or thick, discolored discharge from the wound site is a clear indicator of infection.
Red streaks extending away from the incision line or the development of a fever suggest a spreading infection and necessitate immediate medical attention. If a non-absorbable stitch has been covered by skin, do not attempt to pick at or remove it yourself. Doing so can introduce bacteria, tear the healing wound, or cause the thread to break and remain embedded. A healthcare professional has the sterile tools and expertise to safely retrieve the stitch, ensuring the wound continues to heal properly.