Chromic sutures are a type of surgical material used to close wounds. They are completely absorbed by the body, meaning the body’s own processes break them down over time, eliminating the need for a separate removal procedure. The unique characteristic of a chromic suture is that its natural material is chemically treated to significantly slow down this degradation process. This treatment provides a balance of temporary wound support and eventual disappearance.
Composition and Origin
The core material of a chromic suture is purified collagen, a natural protein fiber. This collagen is sourced from the serosal layer of beef intestines or the submucosa of sheep intestines, commonly known as “catgut.” After processing the tissue into strands, it is twisted together to form the suture thread. The term “chromic” refers to the treatment process where the suture is exposed to chromium salts, specifically chromic acid.
The chemical treatment modifies the material’s structure by using chromium salts to create cross-links between the collagen molecules. These new bonds make the material more resistant to the body’s natural enzymes, effectively “tanning” the suture. This tanning process increases the suture’s durability and extends the time it retains its strength within the wound.
The Absorption Timeline
The breakdown of a chromic suture involves two distinct phases: tensile strength retention and total mass absorption. Tensile strength is the ability of the suture to hold the wound edges together, which is the immediate priority after surgery. Chromic sutures are designed to maintain functional support for the wound for approximately 10 to 21 days after placement.
The loss of strength and subsequent disappearance of the material occur through enzymatic hydrolysis. This involves the body’s natural enzymes digesting the collagen protein. This enzymatic breakdown is less predictable than the hydrolysis used to absorb synthetic sutures and can be influenced by the surgical site. For instance, areas with high enzyme activity, such as the stomach or vagina, may cause the suture to lose its strength more rapidly.
The second phase, total mass absorption, is the time it takes for the entire suture material to completely disappear from the tissue. This complete absorption of the chromic suture material generally occurs over a much longer period, typically ranging from 90 to 120 days. This four-month window ensures the material is fully cleared from the body once the wound has achieved sufficient inherent strength. Therefore, the strength retention phase is short-term support, while the absorption phase is the long-term clearance of the foreign body.
Common Surgical Applications
A surgeon selects a chromic suture when a wound requires temporary support that is longer than what plain gut can provide, but where long-term support is unnecessary. This absorbable nature is particularly valuable in internal procedures where retrieving a non-absorbable suture would be impractical or impossible. The suture is frequently used for soft tissue approximation in areas that heal relatively quickly.
Specific Uses
Specific utility is found in the gastrointestinal tract, the urinary tract, and in many gynecological procedures. Chromic sutures are also a common choice in oral and dental surgery, where they close the mucosal tissue of the mouth. In these environments, the slightly extended strength retention is beneficial, and the fact that the material will dissolve eliminates the need for a follow-up visit just for suture removal. The balance of moderate strength retention and complete absorption makes it a reliable choice for internal ligation and for closing the deep layers of a surgical incision.