Continuing Education Activity
Hypersensitivity reactions are most commonly encountered in the context of immunology. Suture hypersensitivity refers to the clinical entities resulting from an exaggerated immunologic response triggered by the presence of a suture material, which serves as an external antigen. This activity reviews the evaluation and management of suture hypersensitivity and highlights the role of the interprofessional team in the care of patients with this condition.
- Identify the etiology of suture hypersensitivity.
- Describe the physical examination findings of suture hypersensitivity.
- Review the management options available for suture hypersensitivity.
- Summarize the importance of improving care coordination amongst the interprofessional team to enhance care coordination and improve outcomes for patients affected with suture hypersensitivity.
The concept of hypersensitivity is commonly encountered in the context of immunology, where a disproportionated reaction can occur between the effector mechanisms and the control mechanism of the immune system. This produces an exaggerated and often pathologic response by the immune system to an antigen. This response is often linked to the inheritance of predisposing human leukocyte antigen (HLA) genes.
Suture hypersensitivity refers to several clinical entities resulting from an exaggerated immunologic response triggered by the presence of suture material, which serves as an external antigen. While most commonly thought of as a dermatologic phenomenon, this hypersensitivity can arise in deep tissues as well, and its clinical relevance is concerning for wound healing management. Differentiating postoperative infections from hypersensitivity reactions is essential.
Consultation with allergists and dermatologists may be appropriate for the diagnosis of the nature of the surgical site complication and proper management. Suture hypersensitivity reaction complications can increase hospitalization days and health care costs. The interprofessional team, which includes dermatologists, allergists/immunologists, and enterostomal therapy nurse are necessary for the early recognition, diagnosis, and treatment to decrease such complications. The recommended management of hypersensitivity-type reactions is prompt recognition of physical findings and further patch testing. Avoidance of the offending allergen and a combination of topical steroids are started as soon as possible, to prevent any further complications.
Screening panels for surgery-related allergens have not been well established. Some studies have proposed testing for specific allergens in patients with suspected suture hypersensitivity in an attempt to reveal pertinent allergens and prevent future exposure complications.
Suture material placed in human tissue represents a foreign body, and it will provoke an immunologic response. The tissue response depends on the suture material (absorbable versus non-absorbable, synthetic versus biologic), the type of tissue receiving sutures, and the immune system. Inherent properties of absorption, filament number, size, and tissue reactivity are among the features of suture material implicated in the tissue response. The response may be driven by the innate immune system, the adaptive immune system, or a combination thereof. The most frequently implicated agents are macrophages, which are responsible for the cell-mediated response, commonly referred to as type IV hypersensitivity reaction.
To explain suture hypersensitivity, what constitutes a normal tissue response to the presence of foreign material must be established. Sutures serve as a persistent, or even non-degradable, antigen, which elicits a macrophage-dominant reaction over weeks. Activated macrophages often engage in a morphologic change to epithelium-like cells, referred to as epithelioid cells or histiocytes. Granuloma formation constitutes the aggregation of the epithelioid cells, with surrounding lymphocytes. Such reactions are referred to as granulomatous inflammation, which is related to strong T-cell activation and cytokine production. This reaction can also be elicited by foreign bodies that activate macrophages without an adaptive immune response.
Absorbable sutures depend on the tissue response for their timely dissolution. Suture hypersensitivity is related to the duration of suture absorption, developing such a reaction at the end of the absorption process. The sutures' diameter might be critical in this process.
The tissue response elicited by suture material is a specific case of this generalized form of inflammation. The reaction can be broken down into acute and chronic phases. The acute response of tissues to suture is the same for all sutures during the first five to seven days, at least. A postoperative inflammatory reaction and acute suture hypersensitivity are seen within 48 hours after the operation. For absorbable sutures, observable differences in the tissue reaction arise after the acute phase once the absorption phase begins. Catgut appears characterized by a thin capsule of connective tissue and the presence of a few histiocytes and lymphocytes, characteristic of any monofilament suture. After absorption is complete, the site is marked by a collection of monocytes with characteristic brown, foamy cytoplasm. Catgut suture reaction depends on the period of the suture absorption and is mainly histiocytic in type. Instead, non-absorbable sutures are encapsulated by a rim of connective tissue, with surrounding histiocytes, giant cells, and lymphocytes. This is most commonly encountered with silk and cotton sutures, less often with dacron, and least with nylon and wire.
In contrast, non-absorbable sutures remain in tissues indefinitely and exhibit a different tissue reaction. Buried silk produces an initial prompt tissue reaction consisting of mild edema and a collection of polymorphonuclear leucocytes around the suture. By the third day, a few fibroblasts are seen, and the intensity of leukocyte infiltration starts to decrease. As the process continues, there is a gradual increase in monocytes, giant cells, and round cells and a decrease in polymorphonuclear cells. Fibroblasts penetrate between the silk fibers and eventually form a fibrous capsule around the suture material.
The reactions to silk may be divided into two major types. In the first and most frequent, the suture remains tight and is surrounded by a capsule of fibrous tissue with variable thickness. Also, it is accompanied by a layer of histiocytes from one to three cell layers deep. Giant cells and lymphocytes vary in both occurrence and numbers. In more cellular reactions, capillaries may be prominent. In the second type of response, the capsule is present, but fibroblasts and histiocytes invade the interstices of the suture. In rare instances, the response appears much like granuloma. A foreign body granuloma is a reaction to exogenous or endogenous materials that are too large to be ingested by macrophages. Nylon is the least of all sutures examined for tissue reactions. All specimens contained the monofilament type, and are surrounded by a narrow, compact fibrous tissue zone. Histiocytes adjacent to the suture occur occasionally; giant cells rarely. No fragmentation of the suture is seen.
The extent of the tissue reaction also depends on the tissue receiving the suture material. Bladder lumen exposure with silk and mersilene sutures produced significant tissue reactions and stone formation. In comparison, with monofilament polypropylene sutures, this reaction wasn't present. Plain catgut produced the least tissue reaction. Lower degrees of foreign body reaction, inflammation, and stone formation were encountered when using 4/0 polydioxanone.
The development of a foreign body granuloma may be associated with an immunoreaction of macrophages. A giant cell, an inflammatory reaction to foreign material, is thought to underlie the various clinical manifestations of suture hypersensitivity.
Tissue reactions to the suture material are rarely reported. The immune status of the recipient plays a role in the immunologic response to the suture antigen. However, people with a predisposition to allergies and autoimmune diseases are more likely to develop hypersensitivity reactions. Conversely, immunosuppressed individuals may be less likely to develop hypersensitivity. In one study, suture specimens were obtained from 12 renal transplant patients. All were receiving azathioprine and, most of them, steroids. Catgut, silk, nylon, and dacron were examined. The transplant had been less than 30 days earlier in four patients and ranged from two months to five years in the others. The remarkable finding was the minimal response, either fibroblastic or histiocytic, to the sutures. Actually, in some sections, the stitches appeared to have displaced adjacent healthy tissue without any cellular response.
Chronic irritant dermatitis, allergic contact dermatitis, and contact urticaria are among the responses related to suture reactions. Suture materials related to such responses are silk, catgut, and chromicized catgut. Such reactions are less common in synthetic absorbable sutures such as polyglactin 910 and poliglecaprone 25. In the case of non-absorbable stitches, such as polyamide 6/6 and nylon, both containing the monomer e-caprolactam, the risk of allergic reaction is low. Hypersensitivity reactions have been reported in cases where polypropylene and sterilized sutures with ethylene oxide and triclosan were used. The addition of dye for coloring sutures has also been reported as a cause of hypersensitivity.
Other materials related to hypersensitivity reactions are acrylic resin, cyanoacrylate, and 2-octyl cyanoacrylate. These materials are commonly found on adhesives, plastics, paints, inks, and topical skin adhesives. In the surgical setting, acrylates are found in adhesives and surgical strips for wound closure. Other causes of prior sensitization with acrylates are from sculptured nails, and bone and dental cement. This increases the risk of hypersensitivity reactions. Other allergens commonly found in adhesives besides acrylates are colophony, abitol, abietic acid, benzoyl peroxide, rubber accelerators, and antioxidants. Cases of hypersensitivity reaction while using a hydrocolloid dressing is due to colophonium.
Silk, when compared to catgut, is not only cheaper but is also more easily sterilized. Silk sutures tend to react less with tissues and result in more forcible wound closures. Delayed silk suture allergies are rare. Asthma, interstitial cystitis, and necrotizing granulomas are related to delayed silk allergies. Removing the sutures can eradicate the allergy.
Vicryl sutures are among the preferred sutures of clinicians due to the low antigenicity, and sparse inflammatory infiltrates. Vicryl suture hypersensitivity is very rare. However, cases of suture allergies have been reported as pruritus, edema, pain, and seroma formation. At the moment, no standardized method to test this reaction has been reported. Still, simple placement of a single interrupted suture in the skin can evaluate a suture hypersensitivity.
Cutaneous reactions are related to different types of allergens, such as drug therapy or sutures exposure. These reactions are immune-mediated. They can be divided into two categories: immediate-type reaction and delayed-type reaction. Immunoglobulin E (IgE) or T-cell delayed-type hypersensitivity mediates these reactions. The mechanism of IgE-mediated reactions is well studied and understood. Meanwhile, the process in which delayed-type reactions occur in the skin is less well understood.
Allergic contact dermatitis is the most considered form of delayed-type hypersensitivity reaction, where sensitization to an allergen occurs. This condition is characterized by its acute phase in which erythema, vesiculation, and pruritus occur. The response is elicited by a hapten capable of interacting with cutaneous protein, which can be a chemical such as pharmaceuticals, sutures, and metallic compounds. Haptens are weak allergens requiring sensitization. Studies of the immune system reveal that a complex sequential series of events starts as soon the skin is in contact with the sensitizing agents.
These molecules aren't in direct contact with antigens. Instead, they bind with cellular or extracellular proteins, before the immune molecules are aware. As soon as the hapten is in contact with the skin, they are taken via pinocytosis or endocytosis by the antigen-presenting cells in the skin. These antigen-presenting cells upregulate the expressions of surface molecules and cytokines. The major histocompatibility complex (MHC), and CD80, a costimulatory molecule, are good examples of such surface molecules. In the dermis and epidermis, the primary antigen-presenting cells are the Langerhans cells. These cells are activated and migrate to the lymph nodes, where they continue to carry the hapten and present the antigen-MHC complex to a T-cell.
The activation of a T-cell requires two signals. The first signal is the contact of the peptide/MCH complex expressed on the antigen-presenting cell with their respective T-cell receptor. The second signal comes when the costimulatory molecules on the antigen-presenting cell interact with their respective T-cell receptors. Once the antigen is presented and the T cells activated, a transition from a naive T-cell to a memory T-cell or effector T-cell occurs. The population of T-cells with a skin-homing receptor could be created if the clonal expansion of suture-specific T-cells occurs. The second interaction of the suture with a T-cell receptor will trigger a cascade reaction of cytokine secretion, cytotoxicity, or proliferation in reactive T-cell clones.
Keratinocytes are essential players in the immune responses in the skin, especially in the activation and prolongation of such a response. They can present antigens when inflammatory stimuli are present. Cytokines play an essential role in the cutaneous immune response. They are secreted by the skin cells after being activated by an allergen playing a crucial role in regulating cell killing. Cytokines, in combination with nitric oxide, secreted from keratinocytes and Langerhans cells, after exposure to allergens, have been considered to direct effector cells to the inflammation site. Examples of such effectors cells are T-cells, macrophages, and neutrophils. Once the inflammatory insult occurs, tissue damage is caused. This tissue damage is believed to release pro-oxidants species, and these reactive oxygen species have been demonstrated to cause necrosis at a high level. On the contrary, low levels of reactive oxygen species induce apoptosis.
History and Physical
Patients should be asked whether they have a history of allergies or prior reactions to suture materials. Observe the proximity of the patient's symptoms to previously operated sites. The list of relevant clinical entities includes, but is not limited to, erythema, swelling, nodular mass, extrusion of the suture through an incision, pruritus, edema, pain, and seroma accumulation. Other possible findings are surgical adhesions, wound dehiscence, infection, and intestinal obstruction along the line of suture material and granuloma formation. When a patient is presented with wound infection or leakage, a suture reaction should be kept in mind.
While the diagnosis is clinical, the distinction of suture hypersensitivity from the normal process of wound healing may not be straightforward. However, the clinical relevance of this distinction depends on the severity of the tissue reaction and is warranted in the most severe cases.
Additional testing is usually not required except in a few select cases or scenarios. If confirmation is desired, skin allergen testing is sufficient. The test involves re-exposing the individual to the culprit suture material and observing for a reaction. Placement of a single interrupted suture exposes the content to the dermis, where the stitch is commonly placed, allowing for a response to occur. In cases involving prior oncologic surgery, it may be necessary to perform a biopsy to rule out the recurrence of the malignancy.
Patch testing like the American Contact Dermatitis Society Core allergen series, the North American Contact Dermatitis Group patch test, and the thin-layer, rapid-use (TRUE) test is a vital tool for the recognition of the offending agent. None of the patch series screens for allergy to 2-octyl cyanoacrylate which is found in topical skin adhesives. In cases where such patches are not available, it has been suggested to consider testing with a suture through the skin versus placing the offending agent against the skin. In the case of suspected topical skin adhesives allergies, a stand-alone, cutaneous test is recommended.
For suspected cases involving deeper tissues, sonographic evaluation is useful. Suture granulomas in the abdominal ultrasound manifest as nodular hypoechoic lesions. A pathognomonic sign of this type of granulomas in the sonogram is the presence of a double hyperechoic line. Granulomas with clinical presentation can present with slight peripheral vascularization on ultrasound.
Treatment / Management
The extent of tissue reactivity inherent to a given suture material is essential to consider when selecting sutures. In general, tissue reactivity tends to be lower in non-absorbable sutures, moderate in synthetic absorbable sutures, and highest in sutures from a xenobiotic material source.
Treatment depends on the extent the hypersensitivity reaction complicates the healing process, its secondary complications, and how far from the initial procedure it arises. Successful treatment of chronic inflammation is achieved with surgical removal of the offending allergen. The healthcare team should start treatment with topical corticosteroid creams, oral antihistamines, topical immune response modifiers, and moisturizers. Systemic corticosteroids can be given in some cases.
It is essential to distinguish a hypersensitivity reaction from common coexisting postoperative complications, such as scarring, bleeding, hematoma, infection, abscess, and wound dehiscence. In some cases, they may be secondary complications of a hypersensitivity reaction.
Suture hypersensitivity can mimic primary granulomatous disorders. It is crucial to be able to distinguish between this foreign-body reaction and the recurrence of malignancy or wound infection. Differentiation from a malignant lesion or an infection can be achieved with a wound fine-needle aspiration and wound culture with staining, respectively.
Patient prognosis will depend on the tissue involved and the severity of the suture hypersensitivity complications. In most circumstances, this is a self-limited condition without significant consequences.
The complications of suture hypersensitivity depend on the type of suture material used and the tissue being sutured. In general, the extent of inflammation, congestion, and foreign body reaction may complicate wound healing in any tissue. Amongst the complications are the following: postoperative adhesions, wound dehiscence, infection, and intestinal obstruction along the line of suture material to which the patient had been sensitized during a previous surgery. Suture materials increase the potential of bacterial colonization with low degrees of virulence in sites they occupy and may lead to infections, like Staphylococcus epidermidis infection.
In the urinary system, this reaction may serve as a lithogenic nidus, which may be further complicated by obstruction and infection.
In vascular and gastrointestinal anastomosis, suture hypersensitivity may be the cause of the breakdown of such anastomoses.
Deterrence and Patient Education
The patient should provide their prior allergy history. Once the patient has such reactions, it is important to avoid such allergens to avoid further complications. Also, patients must be aware of the signs and symptoms of surgical suture hypersensitivity, such as erythema, swelling, nodular mass, extrusion of the suture through an incision, pruritus, edema, pain, seroma accumulation, and post-operative adhesions. The patient should be educated to contact the primary care team for proper complication management. Patient compliance with team recommendations for diets, follow-up, and wound care is essential for proper wound healing.
Enhancing Healthcare Team Outcomes
An interprofessional team that provides an integrated approach, and specializes in postoperative care is essential to achieve the best possible outcomes in patients presenting with suture hypersensitivity. It is crucial for healthcare providers to avoid products with potential allergens when treating patients with suspected wound hypersensitivity. The primary clinicians should know the signs and symptoms of suture hypersensitivity. Wound hypersensitivity is suspected if eczematous changes appear around the wound. Once suture hypersensitivity is suspected, removal of the allergen is required to avoid further recommendations.
Early consult with a dermatologist, allergist/immunologist, nutritionist, and enterostomal therapy nurse is recommended for proper diagnosis and management of complications. If the wound opens, anastomotic rupture occurs, or bowel obstruction occurs, the surgical team must be contacted. In case the team is unable to find the allergen, patch testing for potential allergens can be performed after a review of the allergen exposition. In case the health care team is unable to find the potential allergens, skin testing with pieces of the patient's wound care products like bandages, ointments, and dressings could be done. If necessary, these products should be covered and left on the skin for 48 hours, to help identify the potential allergens that do not appear in the standard patch test series. Once the allergen is identified and removed, the team should start the treatment that includes corticosteroid creams, oral antihistamines, topical immune response modifiers, and moisturizers. Systemic corticosteroids could be started in some cases.
If a surgical wound hypersensitivity occurs, the role of the laboratory and diagnostic laboratory cannot be undermined. If malignancy is suspected, fine-needle aspiration is required for a proper diagnosis. If the patient is to be discharged home with local wound care, consultation should be made with a social worker and community nurse who specializes in wound care and can monitor the patient, give proper wound care and make referrals as needed.
Clinicians should be able to recognize the allergens commonly found in wound care products and their potential for sensitization. It is essential that these wound care products have a complete label of potential allergens on medical devices like dressings, ostomy appliances, adhesives, and bandages, for possible allergen screening. Also, these manufacturers should be encouraged to eliminate common allergens from wound care products. Interprofessional team collaboration in decision-making and communication are key elements for a good outcome. Patients with suture hypersensitivity have a better prognosis and outcomes when signs and symptoms are identified early.