Treatment of Postherniorrhaphy Inguinal Abscess by Hydrofiber: A Possible Option of Leaving Mesh In situ?

Hernia surgery is one of the most commonly performed operations in surgical practice. Groin hernia surgery is associated with a number of complications including visceral injury, neuro-vascular injury, seroma formation, anesthetic complications, infection, and those related to prosthesis. With the increasing utilization of prosthesis in hernia surgery a number of complications became evident, and several dismal outcomes occurred as a result of prosthesis misuse. Previously it was believed that the incidence of infection in mesh hernioplasty was more common than conservative surgery.^1,2 However, recent data suggests that acceptable rates of infection (lower than 2%) can be achieved in patients undergoing mesh hernioplasty.^3–5 Although, when infection occurs it should be treated promptly in order to prevent local and systemic measures. The following case examines a postherniorrhaphy inguinal abscess treated with a silver-containing wound care product.

Case Report

A 75-year-old woman was admitted to the authors’ clinic with pain, swelling, and purulent discharge located in the right inguinal region. She had undergone a right inguinal herniorraphy at another clinic 2 weeks prior to presentation. Physical examination discovered the patient was septic with a 38˚C body temperature, 109/min pulse, and 100/60 mmHg blood pressure. The patient’s right groin was swollen, the suture line was hyperemic, and she had muscular tenderness in the same area. Abdominal computerized tomography (CT) performed at another clinic revealed the presence of collection (abscess) located at the right lower quadrant of the abdomen with possible interaction with the peritoneal cavity. Abdominal ultrasound detected approximately 500 cc of subcutaneous pus collection, gallbladder and urinary bladder stones, and grade II hydronephrosis at the right kidney. The patient’s leukocyte count was 11.900/cc; hemoglobin 13.4 g/dL; and platelet count 358,000/cc. The blood glucose level was 82 mg/dL and liver function tests were within normal limits. Blood urea nitrogen (BUN) was 104 mg/dL (N: 7–22), creatinine 9.5 mg/dL (N: 0.3–1.3), and potassium 6.6 mEq/L (N: 3.5–5.5). Other electrolytes were within normal range. The patient was diagnosed with acute renal failure, and was given precedence for immediate hemodialysis before surgery. A double-lumen jugular catheter was applied prior to hemodialysis. After dialysis treatment, her BUN level was 48 mg/dL, creatinine 6.8 mg/dL, and potassium 5.1 mEq/l. The patient underwent surgical drainage and 1 g of cefamezin sodium was administered before surgery for prophylaxis. A 15 cm x 10 cm abscess cavity was found in the inguinal region below the external oblique fascia during the surgical procedure. Samples for culture and antibiogram were taken, the pus was aspirated, all necrotic tissue was excised, and the cavity was washed with 2 L of saline. The prosthesis (polypropylene mesh) was not removed and was left in situ (Figure 1). The entire cavity was filled with (15 cm x 10 cm) of hydrofiber product containing silver (Aquacel Ag Hydrofiber®, ConvaTec, Skillman, NJ) and was left open for secondary healing. The hydrofiber dressing was replaced daily during the first week, and after the first week it was replaced every other day. The patient followed an uncomplicated postoperative course and was discharged 15 days from initial presentation. At the time of discharge, the surface of the mesh was granulated, and there was mild scarring around the wound (Figure 2). Two months later, the wound was almost completely healed without complication (Figure 3).

Discussion

Groin hernia surgery is one of the most commonly performed operations worldwide. With the advent of scientific and medical techniques, surgeons have started to make use of biomaterials to reinforce tissue defects in hernia repair. Historically, first attempts to bridge tissues were performed using homolog or heterolog tissues. Metallic prosthesis and synthetic prosthesis became popular shortly after.^5,6 Today, bioprosthesis is being used in more than 90% of groin hernia operations.⁶ Mesh hernioplasties have opened a new era in hernia surgery but are associated with specific complications. Some of the most debilitating complications of hernia surgery (eg, visceral injury or vascular injury) have been well documented since the antiquity, but surgeons have adopted terms like nerve entrapment, mesh shrinkage, mesh buckling, and eventually, mesh-induced carcinogenesis.⁷ Another important topic in mesh hernioplasty is wound infection, which has been a topic of a number of studies.^8,9 Structural properties of the mesh, such as pore diameter, number of the stitches, filamentous and biological characteristics, play a vital role in determining the risk of developing infections.10 Mesh related infection is particularly more prevalent in meshes with a pore diameter of less than ¹⁰ µm. Conversely, macroporous meshes are associated with increased rates of adhesion and seroma formation.¹¹ Mesh type is also an important factor with regard to postoperative infections, because increased infection rates are observed in multifilamentous polyester meshes in comparison to polytetrafluoroethylene (PTFE), monofilamentous, or waved polypropylene meshes.¹²
It should be emphasized that the surface of the biomaterial serves as a binding site for microorganisms. The adhesion step is an essential part of infection. Bacteria adhere, colonize, and evoke inflammatory cell migration, thus leading to clinical infection. When placed in vivo, prosthetic materials produce a glycoprotein surface that enables bacterial binding. Van der Waals forces counteract hydrophilic and hydrophobic forces and the microorganisms attach to the gylcoproteinous material almost irreversibly. This allows the bacteria to reproduce as the biofilm polysaccharide slime permit diffusion of nutrients yet isolates the bacteria from surrounding inflammatory reaction.⁸ This mechanism is the key to understanding why systemic antibiotics fail to improve the patient’s condition in the presence of prosthesis. Surgeons have focused on attempts to lower the amount of inert material in the wound, and also to prevent bacterial binding. For this purpose, some have irrigated the wound with antibiotic containing solutions, others have tried to improve operative conditions.^5,13 Despite all of the efforts and the advances in medical technology, a small proportion of patients undergoing mesh herniorraphy develop wound infections. Most of these infections are superficial and are treated promptly without surgical intervention.¹³ Rates of deep groin infection after hernia repair vary between 0.003% and 1.4% and generally occur after the second postoperative week. The most commonly isolated microorganism is Staphylococcus aureus, although streptococcus, peptostreptococcus, gram-negatives, and eventually nontuberculosis mycobacterium have also been isolated.^13–16 No microorganisms were isolated in the patient in the present case, thus it should be emphasized that positive bacterial cultures can be obtained in less than 50% of patients with an inguinal abscess who have either underwent conservative surgical techniques or mesh hernioplasty.¹⁶
The question of whether prosthetic hernia surgery should be done under prophylactic antibiotic coverage has been investigated by a number of researchers.¹³ Validity of these studies lacks homogeneity because of the definition of wound infection by researchers, follow-up criteria, and duration of surveillance. The general attitude in surgical practice is toward utilization of prophylactic antibiotics in hernia surgery.^17,18 Some studies indicate that utilization of mesh in groin hernia surgery does not increase the risk of postoperative infection.¹³
Recent evidence suggests removal of mesh in mesh-associated deep infections,^19,20 especially if PTFE meshes have been used.^21–24 The reason for an aggressive approach in PTFE meshes rely on its biological properties. Since PTFE meshes have a pore diameter of less than 10 mm, leukocytes that have a 75 mm diameter cannot pass through these openings. For this reason, infected PTFE meshes should be removed to avoid the risk of hernia recurrence. Silver has long been used in wound medication and burns due to its histocompatibility and antimicrobial activity. At the beginning of the 20th century, silver was especially used to treat burn injuries, but use of concentrations of silver (up to 30%) available at that time led to discoloration and toxication referred to as “argyria.”^25,26 Recently, a wide spectrum of silver preparations, such as solutions, silver salts, and topical silver sulfadiazine are available. Preparations of silver nitrate have also been used, though its usage has been abandoned because of photosensitivity and temporary skin discoloration.²⁶ The antimicrobial activity of silver-containing wound care products is determined by its ionic silver concentration. The silver hydrofiber dressing used in this case study contains 0.11 mg/cm² silver.²⁵ Silver ion has antimicrobicidal activity at concentrations as low as 0.001 to 0.06 ppm (1µg/mL).²⁶ This concentration allows adequate antimicrobial activity in addition to preventing skin discoloration.

Conclusion

It is difficult to distinguish chronic infection or sinus formation in the present case since the period between the operations was rather short. However, the patient in this case had signs of sepsis and presence of abscess that ultimately led to a drainage operation. The utilization of ionic silver containing wound care products allowed the opportunity to cure the patient without removing the mesh. This report should aid in future cases when operating on patients with deep mesh infections.