Various risk factors associated with SSI have been reported. Fukuda reported that intra-operative blood transfusion, diabetes, and use of steroids were risk factors for SSI following gastrointestinal surgery [21].
Although prophylactic antibiotics were administered up to POD 3 according to the surgeon’s routine use, in the period of the present study, we administered the following treatments according to the common recommendations: OAMBP for elective colorectal surgery [22], a ring drape as a wound protector [3], an absorbable 1 − 0 Coated Vicryl*Plus (Antibacterial)® [23] for interrupted suture of the fascia [24], an absorbable 3 − 0 coated Vicryl for continuous suture of the peritoneum in the subfascial drainage group, an absorbable 3 − 0 coated Vicryl for interrupted suture of subcutaneous fat mass, and an absorbable 4 − 0 Monocryl® for continuous intradermal suture of skin closure [25].
As mentioned before, open laparotomy with gastroenterological surgery is an operation performed with a clean-contaminated wound, resulting in relative high rate (over 10%) of incisional SSI.
In the present study, our hypothesis was that incisional SSI might be prevented by shutout of contaminated fluid raising from the abdominal cavity; however, there has been no report of subfascial closed suction drainage to prevent incisional SSI after open laparotomy. On the other hand, there have been many reports concerning subcutaneous drainage after laparotomy to prevent incisional SSI; however, conclusive results have not been obtained.
In a previous review of subcutaneous drainage, the advantage of closed suction drainage over passive drainage was not shown [15]. Moreover, among studies of subcutaneous closed suction drainage, the results varied [8, 15]. In a review of subcutaneous wound drainage in reducing surgical infection after laparotomy, Manzoor et al. [15] stated that: “There seems to be no benefit in using it in clean and clean contaminated wounds. However, there may be benefit in using drains in patients who are at high risk, including patients who are obese and/or have contaminated wound types.” A recent systematic review and meta-analysis demonstrated that the use of subcutaneous suction drains did not exhibit any significant differences between drained and undrained patients in developing SSI (odds ratio 0.76, 95% CI 0.56–1.02; p = 0.07) [26].
NPWT as a mechanical preventor has been tried, as well as open dirty wound, to reduce incisional SSIs of closed incisions after laparotomy. NPWT has several possible mechanisms, including the prompt removal of exudation to avoid fluid on the inter-stitched face and tissue layers [13]. However, similar to subcutaneous closed suction drainage, conclusive results have not been obtained [14, 16]. Recently, a systematic review and meta-analysis of randomized trials of prophylactic NPWT for closed laparotomy wounds showed that the overall SSI rate in NPWT groups (18.6%, 87/467) was significantly lower than that of standard dressing groups (23.9%, 111/464) (Odds ratio 0.71, 95% CI 0.52–0.99, p = 0.04*) [27].
Subcutaneous suction drainage and NPWT were performed under the hypothesis that the elimination of dead space and fluid collection by active suctioning may prevent wound infection. However, our findings suggest that the beneficial effect of only subcutaneous suctioning remains to be shown.
In the present study, subfascial drainage resulted in no incisional SSIs (0/250) after open laparotomy with gastroenterological surgery. In comparison to the no subfascial drainage group, the subfascial drainage group consisted of more smokers, more previous laparotomies, more emergency operations, worse wound classification, and longer operative time.
Now, we could not understand the preventing mechanism of incisional SSI by the subfascial suction drainage which yielded this striking result. However, the following mechanism might be caused: contaminated fluid from the abdominal cavity sucked below the fascial space; in addition, the exudate under the subcutaneous space sucked through the gap between sutures of the facia.
This retrospective cohort study of incisional SSI has the following limitations. First, this study was performed by one surgeon in one hospital; thus, it was not a randomized trial. Second, the period of study could be divided into early (no subfascial drainage) and late (with the subfascial drainage) periods. Although the same ring drape for wound protection and same absorbable threads for the closure of abdominal wall were used in both periods of this study, some changes of gastrointestinal surgical procedures may have occurred. Third, this study may be the first report of the subcutaneous drainage after laparotomy; thus, randomized controlled trials are necessary to confirm the present findings.