Stapler size independently predicts postoperative complications following stapled ileocolic anastomosis: A retrospective cohort study

Staplers used in ileocolic anastomosis construction differ in length and height. We assessed the impact of stapler type in creating ileocolic anastomoses on postoperative outcomes.


INTRODUC TI ON
Several variations of ileocolic anastomosis after right colectomy have been described.One of these variations includes either stapled or handsewn ileocolic anastomosis.A Cochrane meta-analysis [1] of randomized controlled trials demonstrated a lower risk of anastomotic leak with the stapled anastomosis than with the handsewn anastomosis for patients with cancer but this result was not reproduced in benign indications.Furthermore, the time needed to perform the stapled anastomosis is reported to be shorter than that of the handsewn anastomosis [1,2].
There is a variety of staplers that can be used for the construction of stapled ileocolic anastomosis that differ in length and height.

Study design and setting
This study was a retrospective cohort analysis of an Institutional Review Board-approved (FLA 21-071) database of a tertiary referral centre in Florida, USA.All patients who underwent a laparoscopic right colectomy for colonic adenocarcinoma between January 2011 and August 2021 were included.This study followed the 1975 Helsinki Guidelines and their later amendments and was reported in line with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines [12].

Study population
Adult patients of either sex who underwent a laparoscopic right colectomy for colon cancer were included.Patients who underwent a laparoscopic right colectomy for benign disease (inflammatory bowel disease, trauma, benign polyps or diverticular disease) were excluded.Furthermore, patients operated on using an open approach, laparoscopic cases converted to open and patients presenting with metastatic cancer were excluded from the study to minimize confounding factors that may increase postoperative morbidity.This study was approved by our institution's Institutional Review Board.

Data collected
A retrospective medical record review was conducted by two independent authors (Z.G. and R.G.) and a database of patients who underwent laparoscopic right colectomy for primary colon cancer was established.Data collected included patient demographics and preoperative and operative data.

Study outcomes and definitions
The primary outcome was early (30-day) postoperative surgical complications and their predictors.Complications were defined as "any deviation from the normal postoperative course" [13].Postoperative 30-day mortality, operating time and hospital stay were secondary outcomes.
Linear cutting stapler: Available in varying lengths (60 mm, 75 mm, 80 mm, 100 mm) and varying stapler height.The applicable stapler for ileocolic anastomosis is either the blue cartridge (3.8 mm staple height) or the green cartridge (4.8 mm staple height).
Postoperative complications: All postoperative surgical complications occurring within the first 30 days after surgery.

Technique of ileocolic anastomosis
Six senior board-certified colorectal surgeons with adequate experience performed all procedures.Ileocolic anastomosis was extracorporeally performed, using a stapled antiperistaltic technique.The length and height of linear cutting stapler used for creating the anastomosis as well as the instrument used for apical enterotomy closure (linear stapler or linear cutting stapler) and the use and type of any reinforcing sutures were at the discretion of the attending surgeons.

Statistical analysis
Statistical analyses were performed using EZR® (version 1.55) and R software (version 4.1.2)[14].Continuous data were expressed as

What does this paper add to the literature?
Our study concluded that independent predictors of complications after laparoscopic right colectomy were older age, extended colectomy and emergency surgery, whilst use of a 100 mm stapler was an independent protective factor against postoperative complications.mean and standard deviation when normally distributed or otherwise as the median and range.The Student t test or Mann-Whitney U test was used to analyse continuous variables.Categorical data were expressed in the form of absolute numbers and percentages and were analysed using the Fisher exact test or chi-squared test.
To determine the predictors of complications after right colectomy, a univariate analysis was performed using complications as the dependent variable and all possible patient and technical factors as independent variables.Significant factors with P value <0.1 in the univariate analysis were then selected to enter a multivariate binary logistic regression analysis.The area under the curve of the model used was calculated to verify the discriminatory ability of the model.P values less than 0.05 were considered significant.1, while the techniques utilized and compared are depicted in Figure 1.

Technical detail of the ileocolonic anastomosis
The median operating time was 150 (range 41-360) min.All anastomoses were extracorporeally performed in an antiperistaltic fashion.
A 75 mm stapler was used in 49 (18.2%),80 mm in 97 (35.9%) and 100 mm in 124 (45.9%) patients.A linear cutting stapler with a 3.8 mm staple height (blue cartridge) was used in 175 (64.5%) patients and a 4.8-mm staple height (green cartridge) in 18 (7%).In the remaining 77 patients (28.5%), this information was not available from the medical record.The height of the staples used for performing the anastomosis was not significantly associated with postoperative complications (Table 2).

Apical enterotomy
The apical enterotomy was closed with a linear stapler in 54.8% (n = 148) of patients and linear cutting stapler in 45.2% (n = 122).
There was no significant difference in overall complications between the linear stapler and linear cutting stapler groups (29.7% vs. 27.6%,P = 0.38).Overall, reinforcement and/or imbrication sutures were placed on the apical enterotomy closure in 71 patients.The complication rate was similar between the sutured (30%) and the non-sutured groups (29%) (P = 1).The stapler length used for closing the apical enterotomy did not impact postoperative morbidity (Table 2).(Continues)

Factors associated with individual complications
analysed using univariate analysis.The stapled height of the linear cutting stapler (colour of the cartridge) for the anastomosis was not included in the analysis as 28.5% of the records did not capture this detail.Ileus, anastomotic leak and wound infection were not associated with any specific linear cutting stapler (Table 3).
All haemorrhages were reported in patients where closure of the apical enterotomy was performed with a linear stapler (P = 0.07), although the results did not reach statistical significance.The size of the linear cutting stapler for the anastomosis and suture reinforcement of the apical enterotomy did not significantly impact haemorrhage (Table 3).All haemorrhages were treated conservatively without the need for endoscopic or surgical intervention.

Clavien−Dindo classification [10] of complications
A total of 78 complications were reported, the majority of which were classified as Clavien−Dindo 1 or 2, while seven patients required reintervention (one under topical anaesthesia classified as 3a and six under general anaesthesia classified as 3b).Two mortalities were reported.In the univariate analysis, none of the techniques was associated with any grade of complication (Table 4).

Independent predictors of complications after laparoscopic right colectomy
The independent predictors of complications after laparoscopic right colectomy were older age (OR 1.03, 95%CI 1-1.06,P = 0.01), extended colectomy (OR 2.76, 95%CI 1.07-7.08,P = 0.035) and emergency surgery (OR 4.5, 95%CI 1.3-14.9,P = 0.014).Conversely, the use of a 100 mm linear cutting stapler was an independent protective factor against postoperative complications (OR 0.3, 95%CI 0.18-0.85,P = 0.019) (Table 5).The remaining technical variations including type and method of vascular division, height and type of the anastomosis, apical enterotomy closure and the use of indocyanine green for perfusion assessment were not significantly associated with postoperative complications (Table 2).The area under the curve of the model used was 0.688 (95%CI 0.617-0.76),indicating an acceptable discriminatory power of the model (Figure 2).

DISCUSS ION
Laparoscopic right hemicolectomy is one of the most performed colorectal procedures.A cross-sectional study led by the European Society of Coloproctology (ESCP) in 2015 reported a concerning high rate of anastomotic leak rate after right colectomy of 8.5% [3].
The study could not reach any definitive conclusions on the risk factors of leak since there were several technical variations in the ileocolic anastomoses.The question of which technique of ileocolic anastomosis is better and why remains unanswered.
Our study included only stapled antiperistaltic anastomoses.
Despite this technical homogeneity, other variations need to be considered such as the length and height of the stapler used along with the tool used for closing the common enterotomy, and whether reinforcing sutures should be used.
According to the results of our study, 100 mm linear cutting staplers were predictive of reduced postoperative complications by 30% compared to smaller staplers.These findings are consistent with the results of a previous retrospective cohort analysis from our department that showed earlier resolution of ileus and shorter duration of hospital stay with the use of 100 mm linear cutting staplers in comparison to 55 and 75 mm staplers [15].This is particularly interesting given the fact that commonly used endoscopic linear staplers are 60 mm in length.Our study included only patients with extracorporeal anastomosis, therefore we could not make any conclusions on the use of one or two loads for performing intracorporeal anastomosis, which may have a different impact on the complication rate.
Closure of the apical enterotomy with a linear cutting stapler was associated with similar postoperative morbidity to a linear stapler. of age on postoperative morbidity after right colectomy are quite contradictory.Although there are studies confirming our findings regarding morbidity associated with age and emergency surgery [16][17][18], there are also some observational studies that failed to find any association between age and postoperative complications [16,19].
Predictably, increasing the extent of resection and performing surgery in an emergency setting were predictive of higher rates of complications.Patients who undergo an emergency right colectomy for colon cancer usually present with bowel obstruction that warrants urgent intervention without prior patient optimization.Thus, elderly and vulnerable patients may be at increased risk of postoperative morbidity.
The main limitations of our study include being a retrospective single-centre, non-randomized study and during a period in which there were other intervening factors such as the use of three rows of staples and intelligent sealing.Almost all anastomoses were extracorporeal, which did not allow for further analysis of predictors of complications based on the type and method of anastomosis as intracorporeal anastomosis was found to be associated with lower rates of complications [20][21][22].The numbers included are relatively small yet were sufficient to obtain significant results in the multivariate analysis.We attempted to reduce heterogeneity in the surgical technique by including patients operated in one centre by the same surgeons using standardized methods, techniques and equipment throughout the study period.Such standardization would have been difficult if multiple centres were included since the nuances of the surgical technique may vary among different centres.Nonetheless, a larger multicentre study would be needed to confirm the preliminary findings of our single-centre study.

1 .
Baseline parameters: sex, age, body mass index, American Society of Anesthesiologists classification, comorbidities and tumour location.2. Technical details: surgical urgency, extent of colectomy, technical variations in the anastomosis (isoperistaltic vs. antiperistaltic, hand-sewn vs. stapled, size and colour of linear cutting stapler used, apical enterotomy closure), intra-operative complications and blood loss.

A
total of 270 patients (136 (50.3%) males) with non-metastatic colon cancer were included in the study.The median patient age was 70.2 (range 30-94) years and the median body mass index was 27 (range 17-50) kg/m 2 .Adenocarcinoma location was in the ascending colon in 34% of patients, caecum in 32.2%, hepatic flexure in 14.5%, transverse colon in 11.1%, appendix in 5% and ileocaecal valve in 3.2%.Twenty-three patients underwent extended right colectomy while 247 underwent standard right colectomy.A summary of all baseline characteristics of the study population is shown in Table Factors associated with complications directly related to the anastomotic technique such as ileus, haemorrhage, anastomotic leak (defined as clinical or radiological) and wound infection were TA B L E 1 Study population demographics.
Univariate analysis of factors associated with complications in ileocolic anastomosis.
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index.F I G U R E 1 Technical variations in performing stapled antiperistaltic ileocolic anastomosis.TA B L E 2 All complications according to the Clavien−Dindo classification.
TA B L E 3 Factors associated with anastomosis-related complications: N (%).