Perioperative infections occurring in surgery are referred to as surgical site infections (SSIs) by the U.S. Centers for Disease Control and Prevention (CDC); this term is also used in Japan.¹ Additionally, the CDC developed a method to determine the risk index for preoperatively predicting the incidence of SSIs through risk factor scoring. In 1999, guidelines for preventing SSIs were published.² In Japan, various SSI prevention measures and an SSI surveillance procedure have also been introduced by referring to these examples. The Japanese Nosocomial Infection Surveillance (JNIS) system (renamed Japanese Healthcare Associated Infections Surveillance [JHAIS] in February 2008), similar to the National Nosocomial Infection Surveillance (NNIS) system, was launched, and surgical operations were included in 2002.

According to the NNIS system report, SSIs rank third among nosocomial infections.^3,4 In terms of nosocomial infections in surgical patients, SSIs were ranked the highest at 38%, of which wound infections accounted for two-thirds, and organ and body cavity infections accounted for one-third.⁵ Thanks to various SSI prevention measures in recent years, the incidence of wound infections has tended to decrease, but an incidence of approximately 10% has still been reported to date.⁶⁻¹¹ Generally, the occurrence of SSI results in longer hospital stays and increased hospitalization costs.^12,13 Smith et al reported that a wound infection would mean an additional medical cost at home, even if the patient is not staying in the hospital.¹⁴ Therefore, additional measures are important to prevent SSIs.

In the present study, in addition to the general wound infection countermeasures, we performed a subcutaneous scrubbing procedure with gauze during abdominal closure in colorectal cancer surgery to examine whether this additional step could change the incidence of wound infections.

Materials and Methods

Of the 290 colorectal cancer patients who underwent elective surgery for intestinal resection (≥D3 lymph node dissection) from 2002 to 2012 in our department, 74 were assigned to Group A (operations performed from 2002 to 2003); 76 were assigned to Group B (operations performed from 2007 to 2008); and 139 were assigned to Group C (operations performed from 2009 to 2012) to examine the incidence of SSIs. The NNIS diagnostic criteria were used to define wound infections.¹⁵ In our department, measures for wound infections in colorectal cancer surgery have been implemented stepwise since 2004. By 2007, the procedure had been documented and standardized; therefore, investigation was started. The wound infection rate was reduced in 2007 and 2008, whereas the scrubbing method with gauze was introduced in 2009 to further reduce the infection rate.

We examined patients who underwent laparoscopic surgery, including patients with T3 or lower lesion depths, N1 or lower lymph node metastasis grades and no distant metastases, and those who underwent open surgery.

Prevention of surgical site infection

In Group A, hair was shaved at the incision site on the day prior to surgery. During the colorectal cancer surgery, after intra-abdominal manipulation for removing the intestine, the abdominal cavity was cleansed with a 3000-mL saline solution, and the fascia was closed for abdominal closure. In Group B, the incision site was treated with a hair removal cream on the day prior to surgery. Until 2006, surgery was initiated early in the morning; therefore, hair removal was performed during the previous night. However, since 2007, only the clipper procedure has been used immediately before surgery, according to necessity. During surgery, the wound edge was covered with a drape (3M Steri-Drape Wound Edge Protector 1075, Lexington, MA, USA). Then, at the time of wound closure after primary lesion resection, gloves were changed, surgical tools were replaced with new tools (no change in staff), and the abdominal cavity was cleansed with a 3000-mL saline solution. After the fascia was closed, the subcutaneous site was washed with a 300-mL high-pressure saline solution, and the skin was closed to finish the surgery. In Group C, in addition to the procedures employed in Group B, gauze was used for subcutaneous scrubbing during the high-pressure washing. For the high-pressure washing process, an 18-gauge needle was attached to a 50-mL injection syringe into which the saline solution was drawn, and then ejected in 1 stroke by plunger pressure and sprayed over the wound site for washing (Fig. 1).

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Since 2002, preoperative measures included smoking cessation, nutritional state improvement, and in diabetic patients, reductions in hemoglobin A1c (HbA1c) concentration to 7% or lower. For the intraoperative procedure, the body temperature was maintained at approximately 36.5°C during surgery.

Results

Table 1 shows the breakdown of the cases in Groups A, B, and C. No significant differences were observed in gender, age, American Society of Anesthesiologists (ASA) score, primary site, stage, concurrent disease, bleeding amount, or surgery duration. In Group A, wound infections were found in 17 of the 74 (23%) patients. In Group B, wound infections were found in 11 of the 76 (14.5%) patients, all of whom received wound infection countermeasures; the incidence of infections in Group B was significantly lower than infection incidence in Group A. In Group C, which contained patients who received an additional infection countermeasure, wound infections were found in 4 of the 139 (2.9%) patients, representing a significant reduction from the levels noted in Group A and B (Fig. 2).

Table 1 Patient characteristics

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An additional investigation by year showed no major differences in the frequency of occurrence of wound infections in different years in Group A, but the rate in colon cancer patients was 16% in 2007, 11.5% in 2008, 3.4% in 2009, 2.8% in 2010, 2.8% in 2011, and 2.6% in 2012 in Group B, with the frequency of occurrence of wound infection declining in recent years (Fig. 3).

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Discussion

According to the findings of SSI surveillance procedures in the United States and Japan, SSIs were frequently observed in gastrointestinal surgery cases, especially in colorectal cancer surgery patients.⁴ Even with SSI prevention measures in place, wound infections are known to occur in about 10% of patients.⁶⁻¹¹ Generally, wound infections can increase hospital stay duration/costs and delay social rehabilitation; therefore, it is important to implement SSI-prevention measures. When an intestinal resection is conducted, the bacteria may fall from the resected intestine, and this may be related to wound infections. The number of bacteria in the large intestine is reported to be several thousand times that of the upper digestive tract and is considered to be a major factor for contamination of the surgical site and occurrence of an SSI. The following are possible SSI prevention measures: (1) Devise preparatory procedures to minimize contamination during surgery; (2) Prevent contamination of the surgical site during the operation; and (3) Prevent SSIs from happening even in the existence of a slight contamination by increasing the patient's resistance to infections and by eliminating contamination.⁴

Before 2003, the SSI prevention measures in Japan and in our department were just mechanical colonic irrigation and heeding precautions to minimize contamination of the surgical site during an operation; very few institutions had adopted concrete measures. In our department, the rate of wound infection used to be quite high. Since 2004, measures for wound infections in colorectal cancer surgery have been implemented stepwise. By 2007, the procedure had been documented and standardized; therefore, investigation was started. We cover the wound edge with a drape; then, when closing the abdominal wall, the gloves were changed; the surgical tools were replaced with new ones; and high-pressure washing was conducted with a 300-mL saline solution. Thus, the incidence of wound infection could be significantly reduced in our department, reaching about 10%, which was nearly equivalent to the average level given in reports. In the present study, we aimed to further reduce the incidence of wound infection. Speculating that a reduction in the number of bacteria at the wound site would be effective, we scrubbed the subcutaneous region with gauze during the high-pressure washing before closing the wound, as an additional procedure. The idea of scrubbing with gauze was inspired by the effectiveness of brush scrubbing for contaminated injuries.¹⁶ The outcome was a reduction in the incidence of wound infection, as expected. We considered that the decrease in the bacteria under the skin possibly brought about the good result. In recent years, laparoscopy has been conducted for a better cosmetic outcome, and the incidence of wound infection from a laparoscopy has been reported to be about 6%, which was lower than that of an open abdominal surgery.⁸⁻¹⁰ If a wound infection occurs in a laparoscopy, the cosmetic aspect will be compromised; therefore, a wound infection should be avoided. After adopting this method, the incidence of wound infection has been reduced to 2% in our department. According to the results of the present study, subcutaneous scrubbing with gauze at the time of high-pressure washing before wound closure was found to be effective, in addition to the general SSI prevention measures. This very simple procedure was considered useful for SSI prevention.