Abdominal wall considerations in re-operative surgery

Fry DE.

Publication Details

In this discussion, reoperative surgery of the abdomen will refer to re-entry of the abdominal cavity prior to completion of the wound healing process from a prior abdominal procedure. Reoperation in this situation usually requires access to the abdominal cavity through the acute or subacute surgical wounds from the prior procedure. Repeated operation through this incompletely or minimally healed wound portends major complications in the abdominal wall (1).

Definitions, pathogenesis, and epidemiology

Abdominal reoperation is necessary in 10–15% of patients who have had an initial abdominal procedure for trauma or for acute bacterial peritonitis. Reoperation is necessary because of intraabdominal bleeding, leaking intestinal suture lines, necrosis of bowel, or abdominal abscess. Reoperation in these circumstances is emergent, hemodynamic circumstances in the patient may be unstable, bacterial contamination is usually extreme, and inflammed and swollen intraabdominal contents may lead to increased tension on the fascial closure of the reoperated wound. Complications at the abdominal wall surgical site may include wound infection, necrotizing fasciitis, dehiscence, and/or evisceration. These complications are associated with each other, and complex patients may meet the criteria for all of them.

Wound infection is the discharge of pus from a primarily closed wound, or evidence of soft tissue necrosis or cellulitis about a wound that remains open for delayed or secondary closure.

Necrotizing fasciitis occurs when the rectus or lateral abdominal wall investing fascia becomes necrotic and undergoes dissolution from invasive infection arising from the surgical wound of the abdominal wall. Fascial necrosis may be associated with ischemia secondary to closure under extreme tension. In complex circumstances, ischemia and necrosis may precede infection, but commonly ischemia and invasive infection are synergistic partners. Fascial dissolution may occur focally or may extend to the full extent of the surgical incision. Necrosis of fascia is accompanied by varying degrees of overlying skin and subcutaneous tissue necrosis, or underlying muscle necrosis.

Dehiscence is the separation of the fascial closure of the reoperated abdominal wound with the exposure of intraabdominal contents to the external environment. Dehiscence is secondary to technical failure of sutures, shear forces from tension, or fascial necrosis from infection and/or ischemia (2).

Evisceration is the uncontrolled exteriorization of intraabdominal contents through the dehisced surgical wound outside of the abdominal cavity. Evisceration may occur from omentum but is of greatest concern when bowel protrudes through the separated fascia. Dehiscence with or without evisceration poses the potential risk of mechanical injury or desiccation of the intestinal wall which may lead to perforation or fistulization of the bowel.

Diagnosis

The diagnosis of wound infection is made from the identification of pus which is discharged from the closed wound. Classic signs of inflammation(e.g. Induration, erythema) suggest infection. Fever in the multiply operated patient is a non-specific finding of little value in the diagnosis. In the open wound, advancing cellulitis and progressive wound necrosis of the soft tissue margins confirm the diagnosis. Cultures are useful from the wound in the multiply-operated patient and will reflect the source of contamination responsible for the infection. Open surgical wounds that are culture-positive or have superficial exudate but are without either necrosis or cellulitis should not be considered infected.

Necrotizing fasciitis is a clinical diagnosis from the identification of necrotic and suppuration of the wound fascia. The infection will be noted to invade laterally from the midline wound. Necrotic fat is commonly present from the subcutaneous space but skin or muscle may show minimal changes. Cultures are of value for the selection of antibiotics. Late necrotizing infection from multiply-operated open wounds may reflect resistant nosocomial pathogens from the intensive care unit environment, and require cultures.

The diagnosis of dehiscence/evisceration is purely a clinical observation. Fascial separation is usually heralded by discharge of serous, bloody, or suppurative fluid from a closed wound. Opening the wound confirms the fascial separation. Fascial separation in the already open wound is readily seen.

Prevention

Prevention of wound infection requires standard principles of infection control in the reoperated patient. Sterile technique and conscientious efforts to avoid wound contamination is essential. Perioperative systemic antibiotics may reduce wound infection rates in the wounds that are closed primarily. Topical antibiotics and antiseptics are not of proven value and may interfere with wound healing or cause tissue injury. In grossly contaminated wounds, leaving the skin/subcutaneous tissue open is advisable. Systemic antibiotics do not reduce wound infection rates in wound that are managed by open methods. Necrotizing fasciitis is purportedly less frequent when contaminated wounds are left open.

Prevention of dehiscence/evisceration entails avoidance of infection, technical errors in closure, minimization of tension on the wound closure, and avoidance of wound ischemia. Little objective evidence supports reduced dehiscence rates from one type of suture over another (3). Monofilament, large caliber, non-absorbable sutures have appeal. Interrupted versus running techniques have comparable dehiscence rates. Retention sutures reduce evisceration risks but not the frequency of dehiscence.

Edematous, distended intestine in the multiply-operated abdomen results in the tense fascial closure which has a high-rate of dehiscence. Severe edema and distention may preclude fascial closure even after attempts at intestinal decompression. Alternative strategies avoid dehiscence, damage to the fascial edges, bowel injury from evisceration, and abdominal compartment syndrome (4) (table I). When an abdominal wall stoma is required, an important strategy is to place it remote from the reoperative open wound if possible to avoid secondary contamination.

Table I. Options for management when the fascia cannot or should not be closed in reoperated patients.

Table I

Options for management when the fascia cannot or should not be closed in reoperated patients.

Management of abdominal wound complications

Management of wound infection from the closed abdominal wound is removal of skin sutures/staples, opening and drainage of pus, and mechanical debridement of fibrin. Systemic antibiotics are not necessary unless necrotic soft tissue or a perimeter of cellulitis is present. The open wound is managed with moist gauze dressings without topical antiseptics nor antibiotics. Secondary intention is required. Invasive infection in open wounds requires debridement of necrosis and systemic antibiotics. Gram stain of exudate may guide antibiotic choice. Debridement may be required daily.

In necrotizing fasciitis, the dead tissues need to be debrided until only viable, bleeding tissue remains. Antibiotic choices are in table II. Localized debridement may spare elements of muscle or posterior fascia. Small areas of debridement may create fascial defects. If no bowel is exposed, these small defects may be subsequently managed by secondary intention or small split thickness skin grafts.

Table II. Antibiotic choices with necrotizing infection of the abdominal wall.

Table II

Antibiotic choices with necrotizing infection of the abdominal wall.

Dehiscence requires consideration for exposed or protruding bowel. Dehiscence with omentum exposed but without evisceration is managed with local care, subsequent skin grafting, and hernia repair as necessary. With evisceration, then a mesh reconstruction is entertained. Mesh is not used when intestinal suture lines are present to avoid fistulization (5) (method 2 in table I). Mesh is then placed 10–14 days later after suture line healing. Either absorbable or permanent mesh is used. Absorbable mesh is less abrasive to the intestine but results in ventral hernia (6). Polypropylene mesh is preferred for permanent results. After granulation of the mesh, then bipedicle flaps are used for closure. Skin grafting on permanent mesh results in buckling of mesh, erosion of skin grafts and delayed fistula from wound contraction. In patients with repeated planned reoperations (eg. Pancreatic abscess) non-absorbable mesh is placed initially and then divided in the midline. Reoperation can proceed through the divided mesh without repeated suturing of fascia. After each procedure, the mesh is sutured back together. The staged abdominal repair(STAR) represents this type of procedure where zippers, velcro, or slide fasteners (Ethizip®) may be used (7).

References

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