Most wound infections are superficial
Approximately 75% of all wound infections involve the skin and subcutaneous tissue layers. Superficial infection is more likely to occur when there is an undrained hematoma, excessively tight sutures, tissue trauma, or a retained foreign material. Edema, erythema, and pain and tenderness may be more pronounced than with cellulitis. A low-grade fever may be present, and incisional discharge typically occurs.
Drainage is the cornerstone of management and requires the removal of staples or sutures from the area. Local exploration is mandatory, and fascial integrity must be confirmed. If a pocket of pus is found, open the wound liberally to determine the extent of the pocket and permit as much evacuation as possible. Wound culture is optional. Institute local wound care and consider adjuvant antibiotics in selected cases.
Ensure fascial integrity
Any infection that arises immediately adjacent to the fascia may have an intra-abdominal component, although that is unlikely. Extensive exploration is warranted to assess fascial integrity.
If intra-abdominal infection is suspected, order appropriate imaging.
Patients who have deep infection usually exhibit frank, purulent discharge; fever; and severe pain. Marked separation of wound edges is often present as well, as is an elevated white blood cell count.
As with superficial infection, the key to therapy is liberal exploration, drainage of the abscess cavity, and mechanical wound debridement. Irrigate the wound copiously using a dilute mixture of saline and hydrogen peroxide to remove any remaining debris. Avoid povidone-iodine solution because it inhibits normal tissue granulation.
The wound may be left open to heal by secondary intention, or it may be closed secondarily after 3 to 6 days, provided there is no evidence of infection and a healthy granulating bed is present.
Consider adjuvant antibiotics, especially when the patient is immunocompromised.
If the wound has pronounced edema and unusual discoloration, consider a serious infection such as necrotizing fasciitis.
Wound dehiscence raises risk of evisceration
Dehiscence of the abdominal incision occurs when the various layers separate. Dehiscence may be extrafascial (superficial disruption of the skin and subcutaneous tissue only) or may involve all layers, including peritoneum (complete fascial dehiscence or burst abdomen).
When bowel or omentum extrudes, the term evisceration is appropriate.
In several reviews of the literature, the incidence of dehiscence ranged from 0.4% in earlier studies to 1% to 3% in later reviews.9-12 Despite advances in preoperative and postoperative care, suture materials, surgical technique, and antibiotics, fascial dehiscence remains a serious problem in abdominal surgery.
What causes wound disruption?
To a great extent, abdominal wound breakdown is a function of surgical technique and method of closure. Although the conventional wisdom is that dehiscence occurs less frequently with a transverse incision than with a vertical one, this assumption is being challenged. A small study by Hendrix and associates found no differences in the rate of dehiscence by type of incision.13 That finding suggests that the incidence of dehiscence is inversely related to the strength of closure.
Selection of the appropriate suture material also is important. In addition, use of electrocautery in the “cutting current” mode when the abdomen is opened causes less tissue injury than “coagulation current.” The latter has a greater thermal effect, thereby weakening the fascial layer.
Patient characteristics that influence wound integrity include comorbidities such as diabetes and malignancy, recent corticosteroid administration, and malnutrition.
Although infection may accompany superficial wound separation, its role in complete dehiscence is unclear.
Conditions that cause abdominal distention, such as severe coughing, vomiting, ileus, and ascites, may contribute to dehiscence, particularly when the closure method is less than satisfactory.
Some authors have found a greater incidence of wound disruption when multiple risk factors are present. In patients who had eight or more risk factors, wound disruption was universal.11,12
Management entails debridement, irrigation, and closure
When extrafascial dehiscence occurs, mechanical debridement and irrigation are usually the only measures necessary before deciding how to close the wound—even if infection is present. Remove all foreign material and excise any devitalized tissue.
As for the method of closure, the choice is usually between secondary closure and leaving the wound open to heal by secondary intention. An alternative to the latter is wound closure after several days, once a healthy granulating bed develops.
Dodson and colleagues described a technique of superficial wound closure that can be performed at the bedside using local anesthesia, with little discomfort to the patient.14 Wound separation caused by a small hematoma or sterile seroma especially lends itself to this type of immediate closure.