In the present study, we analyzed the impact of the type of circular stapler employed for anastomotic fashioning on surgical outcomes after rectal resection. Specifically, the aim was to compare the two- and three-row circular staplers in terms of AL, AS and AH rates. We demonstrated significant advantages in terms of AL incidence when the Three-CS was employed, while the type of circular stapler did not show any influence on AL severity. Furthermore, the two devices were comparable for AH and AS rate.
These results derive from the recent advances in surgical techniques and from the introduction of novel surgical devices that progressively ameliorated post-operative outcomes after colorectal surgery. In this regard, a significant contribution was firstly given by the widespread of DST [8, 20]. The use of linear stapler for rectal resection and circular stapler introduced transanally for creation of anastomoses has demonstrated to increase sphincter preserving procedures, reducing, at the same time, the incidence rate of anastomotic complications and surgery duration [9–11]. Although several comparative studies are present in the literature on DST vs handsewing anastomosis creation, no report is currently present on the comparison among the different technologies of the circular staplers.
Circular staplers have evolved over time, and the Tri-staple™ technology was introduced in 2018. The main goal was to guarantee more secure anastomoses allowing, at the same time, an adequate perfusion of the anastomotic stumps as compared to the two-row devices. Three-CSs provide three rows of staples that vary in height. The innermost row is composed by the shortest staples, with the aim of providing the greatest occlusion and barrier to AL. The remaining rows (intermediate and the most external ones) are incrementally higher in order to further strengthen the closure, reducing, at the same time, pressure on tissues, leading to a more facilitated blood supply through microvasculature. This balance between occlusion, hemostasis and favorable blood supply should hypothetically reflect on lower incidence of anastomotic complications in comparison to the Two-CSs. According to our results, this is particularly true for AL onset. The incidence of AL after colorectal surgery in previous reports ranges between 1% and 26% according to the definition used and to tumor location [3]. A recent report on the validation of the ISREC AL grading on 746 patients documented an AL incidence rate of 7.5%, which is not dissimilar to the 6.6% reported in our experience [21]. When patients were stratified according to the type of circular stapler employed, the Three-CS demonstrated a significantly lower association with AL onset (3.4%) as compared to the two-row technology (9.6%) (p = 0.01). A more than 6% absolute difference in AL rate inevitably make the choice of stapler crucial for the patient, the operating surgeon and the healthcare. Indeed, other than the relevant long-term consequences due to AL manifestation, namely higher rate of local recurrence, impaired quality of life and related mortality rate up to 6.8% (6,7), AL onset leads to overspending in healthcare estimated at approximately 20.000 dollars per patient [22].
Interestingly, although not statistically different, the use of the Tri-staple™ technology was associated to a more severe grade of AL. Specifically, 4 out of 6 ALs (66.7%) of the Three-CS group were classified as grade C in comparison to 5 out of 19 (26.3%) of the Two-CS cohort. This likely finds a justification into the clinico-demographic characteristics of patients. For instance, all 4 patients of the Three-CS population presented a BMI > 25 kg/m2, and a low rectum adenocarcinoma, both characteristics that made them more prone to develop more severe ALs [23–25].
Furthermore, in order to specifically evaluate the prognostic role of the circular stapler on AL onset, we conducted a multivariate analysis. As expected, BMI > 25 kg/m2 and tumor location in the middle/low rectum were confirmed as independent prognostic factors, in line with the majority of reports present in the literature [23–25]. Of note, the use of the Two-CSs was recognized as an independent negative prognostic feature, with an OR of 2.63 [1.07–6.46] (p = 0.03).
As further analysis, we evaluated the potential influencing role of circular staplers specifically on low rectal resections. Indeed, tumor location deep in the pelvis is widely recognized as a negative prognostic feature for AL development, and, despite the recent technological advances, its incidence rate is still reported up to 36% [26]. According to the current literature, the introduction of circular staplers significantly simplified ultra-low and low anastomoses formation, thus increasing the rate of sphincter-preserving procedures [12]. However, their potential influencing role of AL incidence rate is still matter of debate. Overlooking our data, we documented an AL rate of 8.7% (4 out 46 patients). Interestingly, a tendency towards a higher rate of AL was evidenced in case of Two-CS (3-12.5%) as compared to the Three-CS (1-4.5%). Despite this relevant decrease in case of three row technology employment, the difference was not statistically significant, probably due to the low sample size of patients with low rectal tumors.
AS is recognized as another fearful complication of rectal resections. Although the physiopathology of AS is not yet fully understood, tissue ischemia, AL, inflammation and radiotherapy have been associated to its potential development [27–29]. Similarly, diverting ostomies seem to increase the AS rate, probably due to the lack of dilation by fecal stream [30–32]. Interestingly, the use of stapler suturing has been related to higher risk of AS, currently comprised between 0 and 30%, independently of the size of the circular stapler diameter [33, 34]. It has been hypothesized that the use of staplers may induce an overactive inflammation, leading to the formation of a stricture [35]. Other authors proposed mucosal gaps and necrosis areas of the stapled anastomosis as main causes of an increased risk of anastomotic stenosis due to their healing by secondary intention [33]. Despite these premises, as a whole, we reported AS only in 2 out of 375 patients (0.5%), with similar incidence rates between the Two- and Three-CS cohorts (p = 0.23). This would imply that the type of circular stapler does not play any influencing role on anastomotic stricture formation after rectal resection. However, given the low rate of AS after colorectal surgery, a larger sample size of patients is needed in order to draw solid conclusions.
With regards to AH onset, its incidence rate after rectal resection varies between 2.3% and 6% and constitutes a clinical emergency in approximately 1% of cases [36]. As compared to the hand-sewn technique, the use of staplers has been associated to a 2.7% higher risk of AH [37]. Indeed, a previous report on the preliminary evaluation of safety and feasibility of the circular stapler reported an AH incidence rate of 4.2% [38]. However, both the two- and three-row devices have been conceived to apply a proper compression on tissues in order to appropriately balance adequate perfusion and hemostasis. This brought to a significant drop in AH incidence with the introduction of more recent devices. As compared to these data, we noted a more than 3% reduction of AH rate with the more recent Two- and Three-CSs, hypothetically confirming the advantages of the novel devices as compared to the initial ones. Interestingly, no difference was noted between the two technologies in terms of hemorrhage events (p = 0.73), and, notably, all hemorrhagic episodes were successfully treated endoscopically.
Our study presents some limitations. First, its retrospective design could have led to possible selection biases. Secondly, due to the low incidence of anastomotic complications we encountered, the sample size may be not sufficient to draw definitive conclusions. On the counterpart, we presented, for the first time in the literature, a comparative study on surgical outcomes according to the circular stapler technology employed. Indeed, although in a preliminary setting, the more recent Tri-staple™ technology seems to be associated to a significant lower incidence of AL, potentially leading to significant advantages both in terms of short-term and long-term outcomes. Moreover, the monocentric study design has permitted to rely on standardized procedures, thus limiting the potential biases due to technical inhomogeneity.
In conclusion, our retrospective comparative analysis has shown the positive impact of the Tri-staple™ technology in reducing AL rate after rectal resection even for low rectal tumors, while maintaining similar rates of AS and AH in comparison to Two-CSs. It is implicit, however, the need for multicenter controlled trials to obtain stronger evidences to further confirm the potential positive contribution of the Tri-staple™ technology on clinical outcomes.