Internal stitches are placed beneath the skin’s surface to hold layers of tissue together and relieve tension on the external wound closure. Leaving these materials in place is frequently an intentional part of the healing process. Modern surgical practice relies on two distinct types of suture material, each designed with a specific purpose and fate inside the body. Understanding these differences provides clarity about the expected course of recovery.
The Difference Between Absorbable and Non-Absorbable Sutures
Surgical thread is categorized based on whether the body can naturally break it down over time. Absorbable sutures are made from materials like synthetic polymers or from natural sources like purified animal intestines (catgut). The intent behind using these is to provide temporary structural support to the tissue until it has regained sufficient strength on its own.
The breakdown of synthetic absorbable sutures occurs through hydrolysis, a process where water molecules in the tissue slowly attack the polymer chains, dissolving the material. Natural absorbable sutures are broken down by enzymatic degradation, which tends to cause a slightly greater inflammatory response. The material’s tensile strength is lost within weeks, and complete absorption can take anywhere from a few weeks to several months, depending on the specific type and location of the suture.
Non-absorbable sutures are made from durable materials and are designed to remain in the body permanently. Surgeons select this type when long-term tissue approximation or continued tensile strength is necessary, such as in high-stress areas like the fascia (strong connective tissue) or in cardiovascular repairs. Because the body cannot metabolize these materials, they maintain their integrity indefinitely unless they are manually removed.
Standard Fate of Retained Internal Sutures
When internal sutures are left in place, the body typically manages them in one of two predictable, benign ways. For absorbable materials, the expected outcome is complete dissolution. Once the suture’s temporary support role is finished, the material breaks down into simpler compounds that the body eliminates.
For non-absorbable sutures, which are inert, the body initiates a process called encapsulation. This is a normal foreign body response where the immune system forms a thin layer of fibrous scar tissue around the material. The suture is effectively “walled off,” isolating it from the surrounding tissue without causing ongoing inflammation. This encapsulation allows the non-absorbable suture to provide permanent support while remaining an inert presence within the body.
Signs That a Retained Suture Is Causing a Problem
Although most retained sutures are benign, certain complications can arise, signaling a need for medical attention. A common issue is a localized infection, which is indicated by classic signs of inflammation around the surgical site. Symptoms include increasing pain, noticeable swelling, redness (erythema), warmth to the touch, and sometimes a persistent discharge of pus or fluid.
Another complication is suture rejection or extrusion, where the body actively attempts to push the foreign material out through the skin. This can manifest as a small, persistent bump that resembles a pimple or boil, sometimes with the end of the suture material visible or palpable beneath the surface. This is a sign of a strong local foreign body reaction that has moved beyond simple encapsulation.
A suture granuloma is a more significant localized inflammatory mass that forms around the retained suture material. It is a cluster of immune cells, including multinucleated giant cells, that attempt to contain the suture. This mass can present as a firm, tender nodule or lump and may develop months or even years after the initial surgery. If a person notices any new or persistent mass, excessive pain, or drainage at the surgical site, they should seek a medical evaluation promptly.
Medical Diagnosis and Removal Procedures
When a retained suture is suspected of causing problems, a medical professional performs a thorough physical examination and reviews the patient’s surgical history. If the suture is deep or the diagnosis is uncertain, imaging techniques are employed to confirm its presence and nature. High-resolution sonography, or ultrasound, is often the first-line method, as it visualizes the linear suture material and assesses the surrounding soft tissue for fluid collections or granuloma formation.
Once a problematic suture or granuloma is identified, the management strategy focuses on resolution. If symptoms are minor, observation might be sufficient, but symptomatic granulomas or extruding sutures generally require intervention. The definitive treatment for a suture granuloma is surgical excision, which involves removing the inflammatory mass along with the embedded suture material.
In cases where a superficial non-absorbable suture is causing minor irritation or is beginning to extrude, a minor office procedure can be performed under local anesthesia. For a retained anchoring suture, a minimally invasive approach like the retract-and-cut technique may be used. This technique involves gently pulling the suture, cutting it, and allowing it to retract, avoiding a larger incision. Complete removal of the inciting material is important to alleviate symptoms and prevent recurrence.