Defunctioning Stomas Result in Significantly More Short-Term Complications Following Low Anterior Resection for Rectal Cancer

This is a retrospective cohort study of consecutive patients with rectal cancer treated by elective low anterior resection of the rectum at a single hospital trust comprising two hospitals between 1st January 2009 and 31st December 2014. All procedures were performed or directly supervised by colorectal surgeons trained in TME. The procedures adhered to the principles of total mesorectal excision or tumour-specific modified mesorectal excision depending on the level of the tumour. In general, total mesorectal excision is performed for all middle and lower rectal cancers while modified tumour-specific mesorectal excision can be used for upper rectal cancers, with the mesorectum divided no less than 5 cm below the margin of the tumour [14]. Defunctioning stomas were created at the discretion of the operating surgeon. Perioperative management was based on an enhanced recovery after surgery protocol including essential principles as per ERAS society guidelines, including pre-operative counselling and education, medical optimisation, no overnight fasting, pre-operative carbohydrate loading drinks, standard management for premedication, analgesia and post-operative nausea and vomiting, venous thromboembolism prophylaxis, antibiotic prophylaxis, avoidance of nasogastric tubes and abdominal drains, early post-operative diet and early mobilisation [15]. Sample size calculation was performed based on detecting a clinically significant increase in the overall complication rate of 20% from 25 to 45% (RR 1.8) with a power 0.8 and alpha 0.05, assuming that 65% of patients would have a defunctioning stoma created at anterior resection. An increase in the complication rate of 20% was chosen as an increase in a magnitude significant enough to influence a surgeon’s decision regarding whether to routinely form a defunctioning stoma. The calculation yielded a necessary sample size of 197 patients (128 with a defunctioning stoma and 69 without).

The primary outcome was the overall post-operative complication rate within 90 days of surgery. Secondary outcomes included length of hospital stay, readmission, reoperation, multiple complications, mortality and stoma-related complications.

The Tripartite Consensus Conference on Definitions for Anorectal Physiology and Rectal Cancer definition of low anterior resection was used, which is a colorectal resection with anastomosis of the colon to extraperitoneal rectum (anastomosis below the peritoneal reflection) [16]. Although it is difficult to assign an exact level for the anterior peritoneal reflection in each individual, studies in living subjects place it at approximately 9 cm [17].

Patients with tumours 12 cm or less from the anal verge were included as these patients are consistently likely to have a distal resection margin below the peritoneal reflection, which is consistent with the tumour height used in other studies of low anterior resection [18‐20]. The tumour level was determined by the pre-operative MRI scan as MRI provides an objective, accurate and reproducible means of assessing rectal tumours [21] and documentation of the level of the tumour from the anal verge is now internationally accepted as a reporting standard for pre-operative MRI [22, 23]. If the tumour level was not documented pre-operatively then patients were included if histopathological analysis of the resection specimen clearly showed a distal resection margin below the anterior peritoneal reflection.

Data were collected by exhaustive review of patients’ clinical notes, operative record, post-operative follow-up visits and reports of radiological and histopathological findings. Data collected included patient demographics, comorbidities, ASA score, body mass index (BMI), pre-operative radiological staging, neoadjuvant therapy, surgical technique, date of stoma reversal, length of hospital stay, outcomes within 90 days of surgery including post-operative complications, mortality and reoperation, and histopathological staging and findings.

Short-term post-operative complications were defined as complications within 90 days of the primary operation and stratified according to the Clavien–Dindo classification [24]. Multiple complications were defined as ≥2 complications of any Clavien–Dindo grade experienced by the same patient. Ileus was defined as non-mechanical bowel obstruction requiring the passage of a nasogastric tube associated with high volume aspirates and bowel obstruction as radiological evidence of bowel obstruction with a transition point. High-output stoma was defined as production of ≥2000 ml of effluent per day.

Comparisons were made between patients who received an initial defunctioning stoma at anterior resection and patients who did not receive a defunctioning stoma. Categorical data were analysed using the Χ² test. Means of continuous data were analysed using the t test. Multiple logistic regression analysis was used to determine significant differences in characteristics between patients managed with and without a defunctioning stoma.

This study was approved by the National Research Ethics Service (REC reference 15/LO/1630). The study was registered with Research Registry (www.​researchregistry​.​com).

Patient characteristics are shown in Table 1. The mean age of patients was 66.9 years, 65% were male, 55.7% had laparoscopic anterior resection and 44.8% had received neoadjuvant radiotherapy. 69% of patients received an initial defunctioning stoma.

Table 2 shows the characteristics of patients with a defunctioning stoma compared to those without. On univariate analysis, there were significant differences between patients who had received neoadjuvant radiotherapy, patients who underwent open surgery, tumour level and the operating surgeon. There were otherwise no significant differences for all other characteristics.

Significant differences identified on univariate analysis were further subjected to multiple logistic regression analysis (Table 3). Only the operating surgeon was independently associated with whether a stoma was formed with one surgeon significantly less likely to use a defunctioning stoma. Surgical technique (open surgery) was not a significant factor.

Table 4 compares patient characteristics according to tumour level. Patients with low rectal tumours were more likely to receive neoadjuvant radiotherapy, in keeping with standard practice in the UK.

The overall 90-day complication rate was 50.2% and 2 (1%) patients died within 90 days of surgery.

Patients who had a defunctioning stoma created had significantly more overall complications than those managed without a stoma (57.1 vs 34.9%, OR 2.48, p = 0.003)(Table 5).

Patients managed with a defunctioning stoma were less likely to require reoperation. There were no significant differences between groups in anastomotic leak rates or abdominal sepsis overall (anastomotic leaks, enterotomy or intraabdominal collection not meeting the definition of anastomotic leak), readmissions or mortality. However, patients who received a primary stoma were significantly more likely to develop post-operative ileus and to experience multiple complications.

Table 6 shows univariate analysis of potential patient and surgical factors associated with post-operative complications, and those with p value <0.2 were subjected to multiple logistic regression to identify independent associations (Table 7). Only the presence of a defunctioning stoma and ASA score ≥3 were independently associated with post-operative complications.

Eleven patients with a defunctioning stoma required a reoperation as a result of complications, which included 7 patients requiring an unplanned abdominal reoperation as follows: 2 patients required an urgent early reversal of stoma, 2 patients required laparotomy and revision of their stoma for ischaemic necrosis, 2 patients required laparotomy for lavage (one for an intraabdominal collection and another for an anastomotic leak) and one required laparotomy and adhesiolysis to relieve small bowel obstruction. The other 4 patients with defunctioning stomas requiring reoperations all received examination under anaesthesia, lavage ± transrectal drainage for anastomotic leak (n = 3) or suspected haemorrhage from the anastomosis (n = 1). By contrast, 11 patients who did not receive an initial defunctioning stoma required an abdominal operation as a result of post-operative complications. Most abdominal operations in this group were to treat intraabdominal sepsis secondary to anastomotic leak, with 9 patients having a stoma formed at reoperation. Only one patient required the anastomosis to be taken down and an end colostomy formed. Five of the other 8 patients who subsequently received a stoma had the reoperation performed laparoscopically without the need to resort to laparotomy.

Seventy-eight patients (55.7%) who initially received a defunctioning stoma still had the stoma 1 year later. There were many and varied reasons for this including anastomotic stricture requiring treatment (n = 11), medically unwell or too frail for further surgery (n = 11), post-operative complications after original surgery (n = 10), local or distant recurrence detected (n = 14), complications with adjuvant chemotherapy delaying stoma closure (n = 3), suspected abnormalities detected on radiological imaging requiring further investigations (n = 4), other miscellaneous (n = 5) and several due to long waiting list times (n = 20). Thirty-six patients (25.7%) remained with a stoma at the time of last follow-up (mean follow-up 34.4 months). Six (9.5%) patients who did not initially receive a defunctioning stoma remained with a stoma at last follow-up.

There are several limitations to the current study. This was not a randomised controlled study and is therefore subject to selection bias. It is likely that many patients with a defunctioning stoma were considered to be at higher risk of anastomotic leak by the operating surgeon and that the results of this study reflect good patient selection by the operating surgeon, particularly by those surgeons who tend to fashion fewer defunctioning stomas.

A higher proportion of patients receiving a defunctioning stoma in this study had been treated with neoadjuvant chemotherapy or radiotherapy but the groups were well matched in all other respects. It is possible that other risk factors which were not recorded in this study influenced the surgeon’s decision to fashion a defunctioning stoma and these may have predisposed patients to developing post-operative complications. However, there were no differences between groups in mean age, sex, smoking status, BMI, T4 tumours, ASA or Charlson comorbidity scores and it is therefore difficult to speculate on what other risk factors for complications may have been present. We also included as homogeneous a patient population as possible by using objective methods in deciding which patients had a low anterior resection and should be included in the study. The definition varies widely among studies on defunctioning stomas and the majority do not specify the method of measurement. We feel that strategies such as assessment on digital rectal examination or colonoscopy are inaccurate in assessing the tumour level, and rigid sigmoidoscopy was not consistently performed on every patient in this study and is usually done with an unprepared rectum in which tumours were sometimes missed, and was therefore neither as widely available nor objectively reproducible as MRI or the histopathological analysis for this study.

A higher proportion of patients who had laparoscopic surgery were managed without a defunctioning stoma compared to those who had open surgery. However, open surgery was eliminated as a significant factor associated with the decision to create a defunctioning stoma on multiple regression analysis. The difference in the proportion of patients who received a defunctioning stoma was more likely driven by the preference for a more selective use of defunctioning stomas by one of the laparoscopic surgeons compared to those practising mostly open surgery. On multivariate analysis, the operating surgeon, tumour level, length of operation and neoadjuvant radiotherapy were not independently associated with complications. Only the presence of a defunctioning stoma and ASA score ≥3, and not open surgery, were associated with a significantly increased post-operative complication rate, in keeping with evidence that open surgery is not associated with more complications than laparoscopic surgery in rectal resection, with 2 recent well-conducted randomised controlled trials in rectal cancer resection showing complication rates for open and laparoscopic surgery [41, 42].

45% of patients in this study received neoadjuvant radiotherapy, which may be lower than similar cohorts in the USA but is, however, very similar to rates of neoadjuvant radiotherapy to rectal cancer patients in the UK, much of Europe as well as Australia and is therefore representative of other rectal cancer patient cohorts undergoing surgery [1, 41, 43].