A simple bedside technique – gently probing the loosely closed surgical incision to clean it – dramatically reduced infections of contaminated abdominal surgical wounds without increasing pain, according to a report in the April issue of Archives of Surgery.

Use of this wound-probing technique for surgical incisions "will reduce surgical site infection and decrease hospital stay, both of which may result in improved rates of long-term outcomes such as fascial dehiscence and incisional hernias, reduced labor for wound care by nursing staff and physicians, improved cosmetic outcome with primary closure, and possibly reduced overall cost," said Dr. Shirin Towfigh of Cedars-Sinai Medical Center, Los Angeles, and her associates.

"We recommend that wound probing be practiced in the first-line management of incisions after open surgery, such as bowel resection, in the face of contamination," they noted.

Until now, no local wound therapy – including topical antibiotics, subcutaneous drain placement, or delayed primary closure – has been proved to decrease surgical site infection in a rigorous clinical trial. "There is no standard wound management for contaminated wounds, [and] the topic has not been aggressively pursued for decades," the investigators said.

According to surveillance of nosocomial infections in the United States, the infection rate for contaminated surgical wounds is 7% overall, and can rise as high as 50% in certain subgroups of patients.

Some surgeons, including Dr. Towfigh, routinely use this probing technique and report good results anecdotally. In what they described as the first prospective clinical trial of the technique, Dr. Towfigh and her colleagues assessed surgical site infections in 76 adults who underwent appendectomy for perforated appendicitis at a single academic medical center over a 3-year period.

Half of the patients were randomly assigned to have standard primary skin closure with staples (control group), and the other half had loose primary skin closure with staples placed at 2-cm intervals. Postoperatively, the control group had daily swabbing of their closed incision with povidone iodine.

The intervention group had this standard postoperative care followed by wound probing in which dry, sterile, cotton-tip applicators were used to penetrate the skin and soft tissue between the staples, reaching down to the external oblique fascia. Any fluid that was extruded was blotted dry, and the wound was covered with a dry dressing. This process was repeated once daily until the wound was dry and no longer penetrable in this fashion, which usually took 3 days.

The two study groups were similar in terms of demographic characteristics as well as comorbidities that might affect wound healing, such as the presence of diabetes, larger abdominal girth, and higher body mass index. Both groups had similar incisional lengths (approximately 8 cm).

Study subjects were assessed throughout hospitalization, as well as at 2 weeks and 3 months following hospital discharge; 64% of subjects completed the 3-month follow-up. The primary outcome measure was the rate of surgical site infections, defined by both subjective daily evaluation by a surgical team blinded to treatment assignment and objective scores on the ASEPSIS (Additional Treatment, Presence of Serous Discharge, Erythema, Purulent Exudate, and Separation of the Deep Tissues, Isolation of Bacteria, and Duration of Inpatient Stay) instrument.

Only one patient (3%) in the intervention group developed surgical site infection, compared with seven patients (19%) in the control group (P = .03). Moreover, patients in the intervention group did not report greater pain than did those in the control group, either immediately after surgery or at follow-up, Dr. Towfigh and her associates said (Arch. Surg. 2011;146:448-52).

By reducing surgical site infections, the intervention also significantly decreased length of stay, compared with the control group (5 days vs. 7 days, respectively; P = .049), as well as the amount of time that caregivers spent on wound care.

"When primary closure fails or is deemed inappropriate, the wound is opened and allowed to close by secondary intention [that is, packing an open wound multiple times a day]. Closure by secondary intention can be painful to the patient, can be labor intensive, and has a poor cosmetic outcome. Nevertheless it is the most widely used closure technique in adults with contaminated wounds," the researchers said.

"We recommend that wound probing be practiced for contaminated wounds due to open appendectomy for perforated appendicitis. We believe that our results can also be extrapolated to other contaminated abdominal wounds regardless of their incisional length," they added.

The exact mechanism by which this technique prevents surgical site infection is not yet clear, but the investigators surmised that it "allows for drainage of contaminated fluid within the soft tissue, thus reducing the bacterial count while maintaining a moist wound for improved healing.

"We are currently analyzing the bacteriology data gathered from this study to gain insight into the process," Dr. Towfigh and her associates added.

This study was supported in part by a James H. Zumberge Faculty Research and Innovation grant from the University of Southern California, Los Angeles. No financial conflicts of interest were reported.

Postop Probe Technique Cuts Abdominal Surgical Site Infections