|Year : 2013 | Volume
| Issue : 2 | Page : 92-96
Surgical site infection following colorectal cancer surgery: Observations from Zaria, Northern Nigeria
Yahaya A Ukwenya, Adamu Ahmed
Department of Surgery, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
|Date of Web Publication||13-Dec-2013|
Yahaya A Ukwenya
Department of Surgery, Ahmadu Bello University Teaching Hospital, Zaria
Source of Support: None, Conflict of Interest: None
Background: Management of colorectal cancer (CRC) in Nigeria is associated with such challenges as operating on locally advanced tumors. We performed a prospective observational study to assess the prevalence of surgical site infection (SSI) following CRC resection in a low resource setting.
Materials and Methods: Consecutive patients, who had standard oncologic resection for CRC at Ahmadu Bello University Teaching Hospital, Zaria over a 5-year period from 2008 to 2012, were enrolled into the study. From 2010, patients with locally advanced rectal cancers were given neoadjuvant chemoradiation with concurrent 45 Gy external beam radiation over 5 weeks and fortnightly FOLFOX 4 regimen to downstage tumor followed 6 weeks later by surgery. Surgical resections were performed through open laparotomy. The outcome of interest was the development of SSI within 30 days of surgery. Patient and surgical variables were evaluated for association with SSI.
Results: Of 188 patients seen with CRC, 78 (41.5%) had surgical resection and 75 were analyzed for SSI. The prevalence of SSI was 13.7% following transabdominal colectomy, 50% following abdominoperineal resection and 25.3% following overall CRC resection (P < 0.05). There was no SSI in patients whose local tumors were confined to the bowel wall, but 35.2% of patients with locally advanced tumors had SSI (P <0.05). Treatment with neoadjuvant chemoradiation, sex, body mass index, wound classification, surgical procedure duration, use of diverting stoma and perioperative blood transfusion were the significant variables (P < 0.05) for SSI.
Conclusion: We observed that the prevalence of SSI in our setting is high and is possibly due to the difficulties of surgical resection of tumors most of which were locally advanced at the time of surgery among other factors.
Keywords: Colon cancer, rectal cancer, resection, surgical site infection
|How to cite this article:|
Ukwenya YA, Ahmed A. Surgical site infection following colorectal cancer surgery: Observations from Zaria, Northern Nigeria. Arch Int Surg 2013;3:92-6
|How to cite this URL:|
Ukwenya YA, Ahmed A. Surgical site infection following colorectal cancer surgery: Observations from Zaria, Northern Nigeria. Arch Int Surg [serial online] 2013 [cited 2019 Aug 22];3:92-6. Available from: http://www.archintsurg.org/text.asp?2013/3/2/92/122925
| Introduction|| |
In 1992, the Center for Disease Control and Prevention (CDC)'s National Nosocomial Surveillance System (NNIS) renamed surgical wound infection as SSI and classified it into incisional (superficial and deep) and organ space infection.  The increased cost of care, prolonged hospital stay and mortality associated with surgical site infection (SSI) continues to be a cause for concern for stakeholders. An estimated 3-30% of surgical patients undergoing colorectal resection suffer SSI. , In colorectal cancer (CRC) surgery, the situation is further compounded by the use of neoadjuvant chemoradiation, which impairs perineal wound healing and suppresses immune function. The creation of ostomies and total mesorectal excision, which prolong operating time also increases the risk of wound contamination. 
The epidemiology, clinicopathological features and treatment of CRC in Nigerians and other natives of sub-Saharan Africa have been highlighted by numerous authors especially with reference to comparison with the Caucasians. ,,,,,,,,, More cases are now being reported, though the annual incidence continues to be far lower than the Caucasians. The peak age incidence is 10-20 years lower and there are relatively higher prevalence rates for rectal and right colonic tumors. ,, In general, patients are treated at advance stage of disease due to late presentation and possibly, higher incidence of aggressive mucinous cancers. ,,,, Overall resection rates vary from 24% to 60% ,,, and in particular, high morbidity rates ranging from 40% to 50% have been reported following abdominoperineal resection. , In light of these circumstances, we undertook a study of the prevalence of SSI following CRC surgery based on prospective data collection in an economically low resource setting.
| Materials and Methods|| |
We conducted a prospective, observational study of SSI following CRC resection at the Gastrointestinal Unit of Surgery Department, Ahmadu Bello University Teaching Hospital Zaria, Northern Nigeria from January 2008 to December 2012 with approval from the hospital ethical committee. Patients included in this study had standard oncologic resection for cancers of the colon or rectum. Excluded from analysis for SSI were patients who had palliative surgeries or died within 48 h of standard surgical resection.
Elective patients were assessed in the Gastrointestinal Surgery Clinic. Investigations included colonoscopy and biopsy, barium enema, abdominopelvic ultrasound and computerized tomographic scan. From 2010, we introduced neoadjuvant chemoradiation to improve resectability of locally advanced rectal tumors below peritoneal reflection. The protocol consists of 45 Gy external beam radiation given over 5 weeks concurrent with fortnight cycles of FOLFOX 4 regimen (oxaliplatin 85 mg/m 2 intravenous [IV] day 1, 5-fluorouracil 400 mg/m 2 IV bolus followed by 600 mg/m 2 continuous IV infusion for 22 h on days 1 and 2; and leucovorin 200 mg/m 2 on days 1 and 2 as a 2 h infusion before 5-fluorouracil). Surgery was carried out after 6 weeks. Elective patients had mechanical bowel preparation and antibiotic prophylaxis with 1 g ceftriaxone and 500 mg metronidazole given intravenously an hour before anesthesia and repeated if the surgical procedure lasted up to 4 h. Patients who presented as emergencies were resuscitated and prepared for laparotomy. Surgical resections were performed through open laparotomy by the authors and all anastomosis were executed manually. Patients with middle and lower third rectal cancer were given total mesorectal excision. Post-operatively all wounds were inspected daily by members of the Gastrointestinal Surgery Unit. Diagnosis of incisional SSI was made by direct observation by the surgical team followed by microbial examination of wound swabs. The presence of suspected organ space infection was confirmed with abdominopelvic ultrasound. Surveillance for SSI continued after discharge until the 30 th post-operative day.
The outcome of interest was the prevalence and type of SSI within 30 days of surgery according to CDC's NNIS definitions. , Superficial and deep SSIs were considered together in this study as incisional SSI.
Patient's age in years was evaluated as a continuous variable. Other patient characteristics of interest included sex, body mass index (BMI), presentation either as elective or emergency, the presence of comorbidity, whether or not patient received neoadjuvant chemoradiation and hospital stay in days. For tumor stage, patients were analyzed categorically according to whether local tumor was still within colorectal wall at the time of diagnosis (TI and TIIA) or had involved contiguous organs or body wall with or without distant spread (IIB, III and IV). All patients who had bowel preparation and controlled surgical procedure were classified as clean contaminated. Patients who had colonic perforation or inadvertent injury to colorectal wall with spillage of contents during dissection were evaluated together as contaminated or infected wounds. For surgical procedures, patients who had right hemicolectomy and extended right hemicolectomy, left hemicolectomy and extended left hemicolectomy were evaluated together respectively. Other surgical characteristics included whether or not patient received perioperative blood transfusion and the use protective stoma for colorectal anastomosis.
Statistical analysis was performed by using SPSS version 17 (SPSS Incorporated Chicago, Illinois). Quantitative variables were analyzed with t-test while categorical variables were evaluated with Pearson's Chi-squared test and Fisher's exact where appropriate. A P < 0.05 was considered to be significant.
| Results|| |
A total of 188 patients with CRC presented to the unit during the period, consisting of 118 (62.8%) with rectal cancer and 70 (37.2%) with colon cancer. Seventy-eight patients (41.5%) had surgical resection, 53 with transabdominal colectomy and 25 who had abdominoperineal resection. The resection rate for colon cancer (75.7%) was much higher than that of rectal cancer (21.2%). Patients who had resection averaged 45.2 years, with a range of 15-82 years. Seventy-five patients (96.2%) had adenocarcinoma. The rest were stromal tumors (2) and non-Hodgkin's lymphoma (1). Five patients (6.4%) died within 30 days of surgery, including three who died within 24 h of surgery and were therefore excluded from analysis for SSI.
Patient and surgical characteristics of the study population relative to SSI are presented on [Table 1] and [Table 2]. Of the 75 patients analyzed, 19 (25.3%) developed SSI. These included 17 cases of incisional SSI, (10 perineal wound, seven abdominal wound) all managed by wound dressing and two cases of organ-space infection (pelvic abscess), one treated successfully by ultrasound-guided percutaneous drainage while the other succumbed to severe antibiotic-associated enterocolitis.
Of the 51 patients who had transabdominal colectomy, 27 had right hemicolectomy and extended right hemicolectomy, 14 had left hemicolectomy and 10 had anterior resection. Abdominoperineal resection was performed on 24 patients (12 males and 12 females). SSI rate was lowest for left hemicolectomy (7.1%) but followed every other case of abdominoperineal resection. The SSI rate for transabdominal colectomy (13.7%) was significantly lower than 50% for abdominal perineal resection (APR) (odds ratio 6.29, P <0.001). Four of the patients who had APR developed perineal wound dehiscence.
In 21 cases (28%), tumor was found on clinical and histopathologic examination to be confined to the bowel wall (Stages I and IIA). None of these patients developed SSI. However, 35% of the patients who had locally advanced disease with or without distant spread had SSI. With respect to wound classification, 3 patients presented with perforation of the colon including one into the abdominal wall who had right hemicolectomy and two with perforation peritonitis, both of whom had anterior resection and diverting ileostomy. Fifteen patients had intraoperative contamination during difficult dissection, 12 with APR and three while performing transabdominal colectomy. Of the six patients who presented with comorbidity, one had acquired immunodeficiency syndrome, four with controlled type 2 diabetes mellitus and one with controlled hypertension.
Sex, BMI and use of neoadjuvant chemoradiotherapy were the patient-dependent variables that produced significant differences in their SSI rates on univariate analysis while age, comorbidity and presentation as elective or emergency were not significant. For surgical variables, wound classification, type of surgical procedure, procedure duration, use of perioperative blood transfusion and protective stoma were all statistically significant. The development of SSI extended hospital stay for our patients by a further 3 weeks on the average (P < 0.05).
| Discussion|| |
Our study has once more highlighted the challenges of managing CRC in this part of the world. Surgical resection was offered to 75.7% of patients with colon and 21.2% with rectal cancers. Sixty-three percent of colon cancers and 91.7% of rectal cancers had local involvement of contiguous structures. This picture is no different from what has been reported from other centers in Nigeria and sub-Saharan Africa. ,,,,,, We have observed in this study that local tumor stage may influence the risk of SSI following CRC surgery as none of the patients with tumors confined to bowel wall developed SSI compared with 35.2% of patients whose tumors had spread to the body wall or contiguous viscera. With local advancement and transgression of surgical planes by tumor, dissection becomes more difficult. This increases bleeding and perioperative blood transfusion requirements, prolongs operating time and predisposes to bowel injury, spillage and wound contamination; variables, which this and other studies have shown to influence the SSI rate in CRC surgery. 
We believe that the introduction of neoadjuvant chemoradiation to improve resectability of locally advanced rectal cancers along with difficult pelvic dissection for locally advanced rectal cancer contributed to the high rate of SSI (50%) following APR. High rate of perineal wound complications up to 60% has been reported following APR after chemoradiotherapy for the rectal cancer , and high morbidity of 40-50% following APR are not unusual in Nigeria. ,
The SSI prevalence rate of 13.7% following transabdominal colectomy and overall prevalence of 25.3% for CRC surgery are consistent with recent reports, which indicate that SSI rates following CRC surgery have been possibly under-reported. ,, In the literature, SSI rates following colorectal surgery vary widely from 3% to 30%, reflecting differences in the patient population, study methodology, definition criteria and mixing results from benign and malignant neoplasms. ,, Obesity has been identified as a risk factor for SSI in studies from economically advanced countries and a substantial population of Americans (32% of male Caucasians and 50% of female African Americans) for example, are obese.  The average patient with CRC in this study presented with BMI less than 18.5 and valuable time was spent preoperatively to improve nutritional status in elective cases.
The high rate of SSI following anterior resection in this study may not be unconnected with frequent use of protective stoma for difficult manual colorectal anastomosis. The use of stoma for colorectal anastomosis has been identified as an independent risk factor for SSI following colorectal surgery. ,, We found a much higher rate of SSI in the females (41.4%) than in the males (15.2%). This may be a reflection of a higher percentage of females who underwent APR (44.4% as against 26%). Another possible explanation may be the young age of our female patients. We found pelvic dissection more difficult in these females in their reproductive age with bulky uterus than their male counterparts.
The risk of SSI was much higher in our patients who presented as emergency but did not reach a significant level, similar to the report by Walz et al.  In the study by Crolla et al. emergency presentation was a significant risk factor for SSI following colorectal surgery.  The risk of SSI following colorectal surgery in the presence of comorbidities such as diabetes mellitus has been clearly documented in the literature. ,,, This risk was not overtly demonstrated in this study possibly due to the quality of perioperative control or the effect of the study sample size.
The detrimental relationship between perioperative allogeneic blood transfusion and SSI following colorectal surgery observed in this study continues to attract attention. Meta-analysis by Hill et al. and other studies have demonstrated clear association between allogeneic blood transfusion and SSI. ,,, Some studies have shown that this relationship exists only when blood is transfused intraoperatively and post-operatively and not preoperatively while newer studies are pointing to marginal or none existent effect when other confounding factors such as difficult dissection and severity of illness are considered during the analysis. ,,
We had a number of limitations in this study. The sample size is very small compared with 2809 patients reported by Tang et al. for colorectal resections  and 611 CRC patients analyzed by Serra-Aracil et al.  Other variables such as intraoperative hypotension and hypothermia and 48 h post-operative hyperglycemia, which are known to influence SSI were not assessed in our study. Furthermore, we depended upon digital rectal examination to decide whether low rectal tumors had invaded pelvic wall or contiguous organs prior to chemoradiotherapy. This may not be very accurate as reported by Rahman and Braimoh. 
| Conclusion|| |
We report high SSI rates following CRC resection. We observed a significant increase in risk of SSI for operations on the rectum, particularly for patients with locally advanced tumors who had neoadjuvant chemoradiation or intraoperative contamination. Other significant factors included prolonged operating time, use of diverting stoma and perioperative allogeneic blood transfusion. We recommend a national multicenter study to verify these factors and apply the knowledge to reducing SSI following CRC surgery in our setting.
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[Table 1], [Table 2]