Advantages of ligating the rectum with gauze pad band in laparoscopic anterior resection of rectal cancer: a propensity score matched analysis

Every rectal adenocarcinoma patient undergoing LAR for middle and low rectal cancer with TNM stage I, II, III between January 2018 and December 2020 was included in this study. We excluded patients with a history of preoperative abdominal surgery or who underwent emergency surgery. Patients with urinary or sexual dysfunction preoperative and those without colonoscopy and pathology reports were not included. Patients with distant metastases were excluded by Chest CT scan, abdominal CT scan and CT or MRI before surgery. Patients who had complete response after neoadjuvant chemoradiotherapy suffered a “watch and wait” nonoperative management approach and were excluded from the study. Finally, 76 patients using GPB and 157 patients using traditional method were selected in our study. All patients selected in this study signed informed consents. Baseline demographic, intraoperative, postoperative, pathological data were collected and postoperative complications were graded with respect to the Clavien-Dindo classification system [13].

According to ESMO guideline, the tumors were classified as low (≤ 5 cm), middle (> 5 cm, ≤ 10 cm) and high (> 10 cm, ≤ 15 cm) [14]. The distance between the tumor lower edge and the anal margin was measured by colonoscopy and digital rectal examination. We performed tumor staging and classification by preoperative colonoscopy, pelvic MRIs, and pathological results according to the 7th edition of AJCC guideline [15].

PSM was performed for the aim of minimizing selection bias caused by retrospective analysis [16]. Bivariate logistic regression was used to calculate the propensity scores for each patient based on the covariates of tumor location, height of the tumor and neoadjuvant chemoradiation. PSM was obtained at a 1:2 ratio between two groups. Ultimately, 63 patients who underwent LAR with GPB and 126 patients who underwent LAR with traditional instruments were enrolled and analyzed after being matched.

The GPB (Henan Piaoan Group Co., Ltd., China) used in the procedure is a tape over the medical gauze pad with a length of 33.0 cm and a width of 1.1 cm (Fig. 1), which is cut off at the attached point of gauze pad.

All surgeons who participated in the study were experts who had performed LAR for > 5 years. Four certified surgeons with over 50 LAR cases performed the operations in traditional instruments. The operations in GPB group were all performed by the same surgeon (X.L.), who had performed over 200 cases of LAR with GPB. The assistants were all qualified physicians who have participated resident training and have more than 50 cases of LAR experience, meeting the Bege’s [17] requirement of 50 procedures in the learning curve for laparoscopic rectal cancer. The assistants’ experience was classified according to the number of years after resident training (> 5 years after resident training or ≤ 5 years after resident training).

The operation was undertaken according to the guideline of TME [3]. When the operator mobilized the rectum and dissected it until weldeyer's fascia level, a GPB was placed into the abdominal cavity via a 12 mm trocar in the right lower quadrant and encircled the rectal canal at least 3 cm at the upper side of the tumor to ligate the rectal canal and the mesentery with only one knot (Fig. 2a, b). Assistant surgeon used instrument to grasp the knotted point and pull the rectum to provide adequate exposure when perform mesorectal dissection. The GPB will be pulled to the left, right and front side (Fig. 2c–f), exposing the corresponding surgical fields. For lower rectal cancer in the deep pelvis, the thread junction can be loosened, moved down to the appropriate site and then knotted to maintain the enough tension.

A linear stapler (Endo GIA™ Ultra Universal stapler 60 mm or 45 mm, Covidien, USA) was positioned in the abdominal cavity for rectal transection. Using the traditional instrument to ligate the rectum, mark the transection line at the right edge of the rectal wall with a clip (Fig. 3a, b). Then use the GPB for pulling the rectum to the left side so that the fork of the linear stapler was placed at a vertical angel to complete rectal transection (Fig. 3c). The difference in the total length of cartridges with GPB and traditional instrument was showed in Fig. 3d. By pulling the rectum, the bowel was fully contacted with the stapler and the rectum could be transected with a cartridge (Fig. 4a, b). For male pelvis and obese patients, a second cartridge may be needed, but an approximate vertical angel could be achieved by pulling the rectum with GPB (Fig. 4c). Finally, the GPB was removed along with the surgical specimen from a small incision. During the operation, be careful not to tie the tumor, which may damage the integrity of the tumor and cause tumor metastasis. Traditional group used traditional instruments to clamp the rectum for surgical field exposure.

The volume of blood loss was measured by negative pressure suction device and the sterile gauze pieces (Henan Piaoan Group Co., Ltd., China).

Three physicians in our pathology department are involved in the processing of gastrointestinal surgical pathology specimens. All pathology specimens in this study were judged by two gastrointestinal pathologists according to uniform criteria, and surgeons were generally not involved in. When fewer than 12 postoperative lymph nodes (LNs) were collected in the rectal specimens, a surgeon and pathologist worked together to find the LNs.

The completeness of TME was accessed by distal resection margin, circumstance resection margin, the number of harvested LNs and positive LNs, and the integrity of mesorectum. According to Nagtegaals’ [18] research, the quality of the mesorectum was categorized in three grades: complete, nearly complete and incomplete.

The primary endpoints included the assessment of the operative findings (operative time (OP), blood loss, number of cartridges used), complication rates 30 days after surgery. The secondary endpoints were the pathology reports, including the positive rate of circumferential and distal resection margin, R0 resection rate, number of harvest LNs and positive LNs, the integrity of mesorectum and the TNM stage.

The data were analyzed by using the χ2 test for comparisons of categorical parameters. The continuous parameters were compared using Student’s t test or the Mann–Whitney U test. A p value < 0.05 was defined as statistically significant. The analysis was performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA).

Table 1 shows the baseline characteristics of the two groups after PSM. Each group consisted of 63 and 126 patients, and the two groups were well matched with no significant differences.

The intraoperative characteristics demonstrated in Table 2 indicated a lower median OP (203 min vs. 233 min, p < 0.001) and intraoperative bleeding (48 ml vs. 67 ml, p < 0.001) in the GPB group. The GPB group had a higher rate of rectum transection with one cartridge (36/63 vs. 51/126, p = 0.030), especially for male (23/37 vs. 29/79, p = 0.010), low rectal cancer (19/43 vs. 20/82, p = 0.023), high BMI (14/21 vs. 19/48, p = 0.038) and tumor > 5 cm (8/9 vs. 9/23, p = 0.032). The 30-day postoperative complications were similar between the two groups (11/63 vs. 23/126, p = 0.893).

Table 3 describes pathological outcomes after surgery. The GPB group had a longer distal resection margin (DRM) than traditional group (2.74 ± 0.76 cm vs. 2.16 + 0.68 cm, p < 0.001). This difference is mainly for low rectal cancer (1.78 ± 0.67 cm vs. 1.23 ± 0.59 cm, p < 0.001). For middle rectal cancer, the DRM was not statistically different (3.03 ± 0.83 cm vs. 2.97 ± 0.77, p = 0.641). The GPB group had a shorter length of cartridges (6.88 ± 1.27 cm vs. 7.28 ± 1.25, p = 0.040). Statistically, the GPB group had more harvested LNs (19 vs. 17, p < 0.001) and positive LNs (1 vs. 0, p = 0.046), had a great number of cases with completeness TME (61/63 vs. 109/126, p = 0.022) than traditional group.

Most studies have shown that extended OP is related to increased risks of surgical site infections (SSI) [19] and AL [20]. Increased intraoperative bleeding has been reported to be associated with increased postoperative complications [21]. In the present study, less OP (203 min vs. 233 min, p < 0.001) and less intraoperative bleeding (48 ml vs. 67 ml, p < 0.001) were found in the GPB group, which similar to the results of Akiyo Matsumoto [10] and Sang Woo Lim [12]. The limitations of performing surgery in a narrow pelvis made it more difficult to provide adequate exposure and maintain proper tension [6]. The GPB provided sufficient tension to pull the rectum, which expose the surgical field in the deep pelvis. This allowed us to mobilize the rectum along the holy plane and avoid intraoperative damage to blood vessels, nerves and organs, which leads to shorter OP and lower blood loss [22]. In our study, the blood loss in GPB group was lesser than NGPB group, it is only few milliliters of blood, although having statistical significance, the effect on postoperative complications was not significant. Less blood loss could decrease the influence on surgical field, allowing for a clearly anatomical level, avoiding damage to the pelvic nerves and helping to reduce OP. Postoperative complication is one of the core indicators to assess postoperative recovery. The complication rate between the two group were similar (11/63 vs. 23/126, p = 0.893), consistent with the previous findings [10, 12], which demonstrated the use of GPB is safe and feasible. Previous studies have reported that OP is associated with SSI [19]. In this study, despite the shorter OP in the GPB group, there was no reduction in the incidence of SSI (4/63 vs. 6/126, p = 0.909). First, all patients in this study underwent LAR which had a reduced incidence of SSI compared to open abdominal surgery [23]. Second, we made only a small incision in the abdomen and used an incision protector for specimen removal to achieve a lower incidence of SSI [24].

Long-term survival outcomes after rectal cancer surgery can be affected by AL [25]. Numerous studies have proposed occurrence of AL is associated with increased use of cartridges during surgery [25‐27]. With this technique, we made fewer cartridges (1 (1,2) vs. 2 (1,2), p = 0.031) and increased the percentage of single cartridge transection (36/63 vs. 51/126, p = 0.030) in GPB group, the results were similar to Wang [11]. A narrow pelvis may led to an inevitable oblique transection with the linear stapler, thus increased the number of cartridges used and total length transected [28]. Repeated stapling at the same closed end [29] may cause tissue ischemia locally and lead to AL [30]. In the present study, we used GPB pulling the rectum to the cranial side to overcome the restriction of the rigid instrument in the narrow pelvis, keep the linear stapler be perpendicular to the major axis of rectal canal, shorten the total length of cartridges (6.88 ± 1.27 cm vs. 7.28 ± 1.25, p = 0.040) and reduce the number of cartridges used.

The AL is related with poor oncologic prognosis [31, 32]. Increased use of cartridges was a risk factor for AL [25‐27, 29, 33]. The number of cartridges reduced, but the incidence of AL (2/63 vs. 4/126, p = 1.000) seemed not decrease in GPB group. Firstly, all patients underwent LAR in this study, the incidence of AL has decreased compared to open surgery [34, 35]. Secondly, the occurrence of AL was also influenced by non-technical factors such as gender, ASA score, preoperative (chemo)radiation therapy, intraoperative complications, precompression before stapler firings, blood supply [30, 36, 37]. A review of the 2 cases with AL in GPB group revealed that 2 patients were both male and 1 had received prolonged chemotherapy therapy preoperatively, which probably increased the incidence of AL. Thirdly, protective ileostomy can reduce the symptoms of AL [38], the protective ileostomy number of patients with a protective ileostomy was higher in both groups, which may hiding the occurrence of postoperative AL. Fourthly, only the patients with AL grade B and C were counted, which may be one of the reasons for the no statistical difference [39]. Additional researches are needed to confirm that GPB could reduce the incidence of AL.

The 9th edition of the JCCRC [40] stated that if tumor is located above or below the perirectal reflection, DRM needs to be at least 3 cm or 2 cm from the tumor lower edge. LAR seemed difficult to obtain adequate DRM, especially for male narrow pelvis and high BMI [6, 41, 42]. Nowadays, relevant studies have now confirmed that DRM of more than 1 cm should be a safe distance [43, 44]. In this study, the mean length of DRM was longer in GPB group (2.74 ± 0.76 cm vs. 2.16 + 0.68 cm, p < 0.001), especially for low rectal cancer (1.78 ± 0.67 cm vs. 1.23 ± 0.59 cm, p < 0.001). It seems similar to the findings of Wang et al. [11] and Akiyo Matsumoto et al. [45]. Sang Woo Lim et al. [12] have reported that DRM did not become longer, but they have discussed that adequate dissection could bring a safe DRM by pulling the rectum. The difficulties to expose the surgical field and get standardized distal margin due to the narrow pelvic space, low tumor position and tissue edema [6], with particularly reference to low-lying rectal cancer or after neoadjuvant therapy. By using a GPB to encircle the proximal rectal canal, the rectum could be pulled from the deep pelvic cavity for fully exposure of surgical field, further dissect the distal rectum and get adequate length of distal margin.

Rectal cancer surgery based on TME principles reduced local recurrence rate and improved 5-year survival rate [2]. Depending on the classification described by Nagtegaal, the integrity of TME can be categorized into complete, nearly complete, and incomplete [18]. In this study, we included the complete and nearly complete of mesentery as standard specimens. 61 (96.8%) specimens have met the standard in the GPB group while 109 (86.5%) specimens in the traditional group have done (p = 0.022). Surgical field exposure in the deep pelvis and the use of rigid instruments increased the difficulty of anatomy [6, 46] and decreased the quality of TME completion [47]. In this study, we minimized the restriction of the narrow pelvic structures by using GPB to encircle the rectal canal and pull the rectum to the cranial side. Unlike rigid instruments, GPB could pull the rectum into every direction in order to expose the tissue around the rectum and avoid damage the integrity of the rectal mesentery. Inadequate elevation of the rectum confused us when dissected the mesentery posteriorly. By stretching the rectum to the ventral side, the laparoscopic can further move to the deep pelvis, helping to identify the anatomical level more clearly and improving the integrity of the rectal mesentery.

The number of detected LNs guarantees the accuracy of postoperative pathological staging [48]. Our study found that the GPB group dissected more harvested LNs (19 vs. 17, p < 0.001) and positive LNs (1 vs. 0, p = 0.046). Previous studies have pointed out [49, 50] the length of resected rectal canal was associated with the number of LNs obtained. We have found that the length of DRM increased in the GPB group, we could remove a sufficient length of rectal canal to ensure completely resection of the LNs.

This study has several limitations. First, this was a single retrospective study, which may have influenced the results, although PSM was used to reduce selection bias. Second, patients in the traditional group were operated by four certified and experienced surgeons, but surgical procedures may have differed depending on surgeon preference, technique, and surgical experience. Further prospective and randomized clinical trials are needed in the future to overcome the limitations of retrospective design and selection bias.