A 3 mm Port Reduces Postoperative Pain After Laparoscopic Colon Cancer Surgery: A Case-control Matched Study.

Between September 2020 and July 2021, patients who underwent laparoscopic anterior resection (AR) or right hemicolectomy (RHC) at Seoul National University Hospital, Seoul, Republic of Korea, were eligible for this study. We used 3 mm trocars and instruments from January 2021 according to the surgeon’s preference. AR was a procedure defined as transecting the rectum above the peritoneal reflection for sigmoid colon or rectosigmoid colon cancer. Patients without colon cancer or who underwent combined resections of other organs (liver, gallbladder, stomach, etc), and those with conversion to open surgery were excluded. Finally, a total of 207 patients were included and their clinicopathologic data were retrospectively reviewed (Fig. 1 ). CONSORT diagram. We used four 5 mm trocars [right upper quadrant (RUQ), right lower quadrant (RLQ), left upper quadrant (LUQ), and left lower quadrant (LLQ) of abdomen], one 12 mm trocar (subumbilicus) in conventional laparoscopic RHC, three 5 mm diameter trocars (RUQ, LUQ, and LLQ of abdomen), and two 12 mm diameter trocars (RLQ, subumbilicus) in conventional laparoscopic AR. The umbilical port site is extended for colon extraction and/or extracorporeal anastomosis. In the 3 mm trocar group, three 5 mm trocars for RHC (RUQ, RLQ, and LLQ of abdomen) and three 5 mm trocars for AR (RUQ, LUQ, and LLQ of abdomen) were replaced with 3 mm trocars (E.Z TROCAR, Win International Co., Ltd.) (Figs. 2 and 3 . The 3 mm trocar has a smaller diameter than the maximal diameter of the grasper head. We used 2 locking grasper for the assistant, and Maryland grasper for the operator’s left hand. The instruments must be assembled intracorporeally after being introduced through 5 mm or 12 mm trocars. The assembly method is as follows: (1) after insertion of the camera port, the operator inserts the 5 mm or 12 mm trocar as the operator’s working port, and then inserts the 3 mm trocar with awl. (2) The guiding rod is inserted through a 3 mm trocar and the distal tip is pushed into the 5 mm or 12 mm trocar. (3) The proximal end of the shaft, which is combined with the jaw, is introduced through the 5 mm or 12 mm trocar and assembled with the guiding rod within the cannular of the trocar. (4) The guiding rod is retracted through the 3 mm trocar and when the combined proximal end of the shaft comes out, the guiding rod is disassembled, and the handpiece is assembled with the proximal end of the shaft. (5) At the end of the surgery, the 3 mm instruments must be disassembled. To ensure no injury to the organs, disassembling and retrieving of the instruments were done under direct vision through an umbilical mini-laparotomy wound. A suture was not needed for the 3 mm port wound; only a small bandage was used. The placement of port sites for the 3 mm trocar group. Port site incisions of laparoscopic right hemicolectomy in 3 mm trocar group. Port site incisions of laparoscopic anterior resection in 3 mm trocar group. Patient-controlled anesthesia (PCA) consisting of fentanyl was used in all patients who underwent laparoscopic colectomy. In PCA, a computerized pump called the patient-controlled analgesia pump, which contains a syringe of pain medication (fentanyl 2000 mcg/100 mL (age >80 y old, 1000 mcg/100 mL) is connected directly to a patient’s intravenous (IV) line. Patients were educated to control the pain by pressing the button on the PCA when the numeric pain rating scale [numeric rating scale (NRS)] was 3 or higher. If the pain was not effectively controlled with PCA, the patients usually requested additional analgesics. A total of 5 analgesics were used (ketorolac tromethamine, tramadol, fentanyl, nalbuphine hydrochloride, and acetaminophen) through IV injection in addition to PCA. Information on the type, amount, and time of all analgesics used was collected. Baseline characteristics and clinicopathological variables were retrospectively retrieved from the electronic medical record system. The data on patients’ characteristics included sex, age, body mass index, comorbidity, American Society of Anesthesiologists classification, previous abdominal operative history, surgery type, and postoperative tumor stage (eighth edition of AJCC). To evaluate postoperative pain, we collected the NRS immediately postoperatively and at 24, 48, and 72 hours after surgery. 13 The use of additional analgesics was analyzed, including the frequency, type, and amount of IV analgesics used immediately after surgery to discharge. Time to first flatus, postoperative hospital length of stay, operative time, intraoperative blood loss, intraoperative transfusion, number of harvested lymph nodes, postoperative complications, and Clavien-Dindo grade were considered as postoperative outcomes. This study was conducted in accordance with the Declaration of Helsinki and was approved by the Seoul National University Hospital Institutional Review Board (IRB No 2106-076-1226) on June 30, 2021. The informed consent was not required because the present study was a retrospectively observational study. Statistical analysis was performed by the Statistical Package for the Social Sciences software (version 25.0 for Windows; SPSS Inc.). Data distribution was evaluated with the Kolmogorov-Smirnov test. The between-group differences of categorical variables were assessed using the χ 2 test or Fisher exact test. The continuous variables that follow the normal distribution were presented as mean ± SD and analyzed through 2 independent sample t test methods. Those with a non-normal distribution were presented as median (range) and analyzed using the Mann-Whitney U test. All tests were 2-sided, and P <0.05 was set as indicative of statistical significance. The logistic regression analysis was performed to determine whether the type of trocar was an independent factor for the use of IV analgesics in addition to PCA. Case-control matched analysis was used to reduce the bias according to the type of surgery using MedCalc Software Ltd.

A total of 158 patients were classified in the 5 mm trocar group, whereas 49 patients were in the 3 mm trocar group. The patient baseline characteristics before and after case-control matching are described in Table 1 . There were no significant differences in sex, age, body mass index, comorbidity, American Society of Anesthesiologists classification, previous abdominal operative history, surgery type, and tumor stage between the 5 mm and 3 mm groups. Because there was a difference in the proportion of the types of surgery between the two groups, the two groups were matched by the type of surgery using case-control matching. After matching, the proportions of the type of surgery in each group were equal (AR: 71.4% vs RHC: 28.6%). There were no significant differences in other variables. Baseline Characteristics AR indicates anterior resection; ASA, American Society of Anesthesiologists; BMI, body mass index; CVA, cerebrovascular accident; DM, diabetes mellitus; HTN, hypertension; RHC, right hemicolectomy. Before matching, the NRS at 48-hour postoperatively in the 3 mm group was significantly lower than in the 5 mm group (3.29 ± 1.01 vs 3.61 ± 0.89, P = 0.049), and the proportion of patients using additional IV analgesics was less in the 3 mm group (22.4% vs 44.9%, P = 0.007). The length of postoperative hospital stays (4.98 ± 0.69 vs 5.67 ± 1.61 d, P < 0.001) was shorter. Blood loss [40 (0 to 50) vs 100 (50 to 150) mL, P < 0.001)] and the number of harvested lymph nodes (24.77 ± 11.75 vs 21.41±12.25, P = 0.085) were also less in the 3 mm group (Table 2 ). After case-control matching, the NRS in the immediate postoperative period (5.24 ± 1.63 vs 6.02 ± 1.48, P = 0.015) and at 24-hour postoperatively (3.65 ± 1.18 vs 4.15 ± 1.19, P = 0.043), and the proportion of patients using additional IV analgesics (22.4% vs 46.9%, P = 0.019) were significantly lower in the 3 mm group than in the 5 mm group. The length of postoperative hospital stay (4.98 ± 0.69 vs 5.67 ± 1.69 d, P = 0.010), intraoperative blood loss [40 (0 to 50) vs 100 (50 to 145) mL, P < 0.001] were also significantly lower in the 3 mm group than in the 5 mm group after matching. There were no significant differences in the number of harvested lymph nodes (22.71 ± 9.95 vs 21.41 ± 12.25, P = 0.568) after matching. Postoperative Outcomes in the Total and Case-control Matched Cohort IQR indicates interquartile range; IV, intravenous; NRS, indicates numeral rating scale; POD, postoperative day. In the multivariable analysis for the use of additional IV analgesics, the type of trocar significantly impacted the proportion of patients using additional IV analgesics (3 mm trocar, odds ratio: 0.330; 95% CI: 0.153-0.712; P = 0.005, Table 3 ). The only other variable that affected the additional IV analgesic use was female sex (odds ratio: 2.453; 95% CI: 1.322-4.549; P = 0.004). Logistic Regression Analysis for the Use of Additional IV Analgesics AR indicates anterior resection; BMI, body mass index; IV, intravenous; OR, odds ratio; RHC, right hemicolectomy. In the present study, we excluded the patients who underwent conversion to open surgery. Because we assumed that the long length of the open wound scar could affect the use of additional analgesics and NRS. A total of 3 patients in the 5 mm group underwent conversion to open surgery, and none of the patients in the 3 mm group underwent conversion to open surgery. Two of the patients had comorbidity of liver cirrhosis and there were difficulties in controlling the bleeding. The other patient who had severe adhesion of previous operation history converted to open surgery.

The use of the 3 mm trocars in laparoscopic colon cancer surgery can effectively reduce postoperative pain, analgesic use, and length of stay while maintaining perioperative safety.

This study demonstrated that using 3 mm trocars in laparoscopic colon surgery reduced the use of additional analgesics and postoperative NRS; therefore, these results suggest the use of 3 mm trocars reduces postoperative pain. The length of hospital stay and blood loss were also found to be less in the 3 mm trocar group. In the logistic regression analysis, the use of 3 mm trocars in laparoscopic colon surgery was an independent factor for the proportion of patients using fewer additional analgesics. We used case-control matched analysis to reduce bias according to the type of surgery, whether RHC or AR. After matching, the use of additional analgesics and NRS were still lower in the 3 mm trocar group. The number of harvested lymph nodes was not significantly different between the two groups after matching. Laparoscopic surgery using a 3 mm trocar is also known as needlescopic surgery or mini-laparoscopic surgery. In the late 1990s, a trocar <3 mm in size was introduced for the first time. In 1999, Ngoi et al 14 reported 36 cases of needlescopic cholecystectomy. In 2001, Cheah et al 15 performed a randomized controlled trial including 75 patients (needlescopic vs laparoscopic cholecystectomy) and demonstrated that patients in the needlescopic group had less pain (mean visual analog score: 2.2 vs 3.6; P < 0.003) and smaller scars (median length: 17.0 vs 25.0 mm; P < 0.001). In addition, patients in the needlescopic group tended to require fewer intramuscular pethidine injections ( P = 0.05). To date, several studies on needlescopic cholecystectomy and gynecologic surgery have been reported 16 – 19 ; however, regarding colorectal surgery, only 2 studies have been reported, which merely describe surgical techniques. 20 , 21 Currently, to the best of our knowledge, there have been no studies that have evaluated the efficacy and safety of 3 mm trocar use in colorectal cancer surgery. In the present study, we assumed that the length of the umbilical mini-laparotomy wound was relatively constant between the two groups because that was determined by the patient’s character not affected by trocar type. A 5 mm trocar was replaced with a 3 mm trocar. The difference in diameter was only 2 mm; however, this was enough to reduce the pain perceived by the patients in terms of NRS and additional analgesic use. Even though the difference in diameter was not large, the resultant skin hole size difference was larger. The reduced pain can be attributable to the fact that when introducing a 3 mm trocar, we just pricked the skin using a #11 blade scalpel, whereas, for a 5 mm trocar, we incised the skin using a #15 blade scalpel. Our results were consistent with the study by Nomura et al, 17 in which rescue analgesic requirement was significantly less in mini laparoscopy surgery for patients with endometriosis, and the results of the randomized controlled trial by Cheah et al, 15 in which the intramuscular pethidine requirement was significantly less in needlescopic laparoscopic cholecystectomy. In 2010, Blinman 22 reported that the risk of morbidity of linear operative scar including pain, dehiscence, hernia, infection, and cosmetic result depends on the total closing tension normal to the long axis of the incision. The total closing tension for a linear incision of a given length is proportional to the square of the length. According to Blinman, assuming that the lengths of the remaining incisions, including LUQ of RHC, RLQ of AR, and mini-laparotomy, are standardized, replacing three 3 mm trocars with 5 mm trocars can result in a tension savings of ~36% in the present study. Before case-control matching, the number of harvested lymph nodes was smaller in the 3 mm trocar group than in the 5 mm trocar group (21.41 ± 12.25 vs 24.77 ± 11.75, P = 0.085), even though the difference was not statistically significant. We considered that the number of harvested lymph nodes would be affected by the type of surgery (higher number in RHC than in AR). In the present study, the mean number of harvested lymph nodes in laparoscopic RHC was higher than that of AR (29.1 ± 13.4 vs 20.6 ± 9.5; P < 0.001). To accommodate this bias, we performed a case-control match analysis for the type of surgery; after matching, the difference in the number of harvested lymph nodes between the two groups was further reduced. As a result, we demonstrated the surgical safety of 3 mm trocars and instruments in colon cancer surgery because there were no significant differences in terms of operative time and number of harvested lymph nodes, and the results were even more favorable in terms of less intraoperative bleeding. Unlike previous studies, we determined the primary outcome as the proportion of patients requiring additional IV analgesics instead of the NRS score. Because we used PCA in all patients who underwent colorectal cancer surgery in our center, we presumed that if pain was effectively controlled, the NRS would be consistent. In the present study, the number of patients who used opioids as additional analgesics was 34 (21.5%) in the 5 mm group and 6 (12.2%) in the 3 mm group, and that of nonopioids was 37 (23.4%) in the 5 mm trocar group and 5 (10.2%) in the 3 mm trocar group ( P = 0.018). The proportion of patients who used additional opioid analgesics was significantly lower in the 3 mm trocar group, as well as that of patients using all types of additional analgesics. It is well established that the postoperative use of opioids is related to postoperative nausea and vomiting (PONV) and postoperative ileus. 23 – 26 As we confirmed that the use of a 3 mm trocar reduced the need for additional analgesics, surgery using a 3 mm trocar could reduce the side effects caused by opioids. During the transition from open surgery to laparoscopic surgery, the demand for smaller incisions and reducing the port number has increased, and many surgeons have made an effort to confirm the safety of single incision or reduced port laparoscopic surgery. 27 However, SILS demands physical and mental distress from surgeons because of the limited motion of the instruments due to internal and external conflicting movements of the instruments. Using 3 mm trocars, more ergonomic surgery can be possible without compromising the benefits of minimal incision surgeries, such as single incision surgery. In this pilot study, we confirmed that the use of the 3 mm trocar was effective in terms of reducing pain and length of hospital stay, and was safe in the aspect of operative time, blood loss, harvested lymph nodes, and postoperative complications. In the logistic regression analysis, the female sex was an independent factor regarding the proportion of patients using additional IV analgesics, as well as the type of trocar. Both before and after matching, the proportion of females in the 3 mm trocar group was high, which might have influenced the results. We performed subgroup analysis according to sex. The number of male patients and female patients were 122 and 85, respectively. We calculated the sample size using Gpower, with a 0.3 correlation coefficient and a 2-sided alpha level of 0.05. To achieve the power of 80%, a total of 84 patients were required. 28 , 29 We found no significant difference in the proportion of patients using additional IV analgesics between the 3 mm and 5 mm trocar groups in males (22.6% vs 33.0%, P = 0.367). However, there was a significant difference in the proportion of patients using additional IV analgesics between the two trocar groups in females (22.2% vs 61.2%, P = 0.004). There have been reports that females show a higher pain score after surgery compared with males; 30 , 31 our study was in concordance with those. In the subgroup analysis, there was no significant difference according to the type of trocar in men; however, there was a difference numerically, which was probably because the number of patients in the 3 mm group was small. In our study, there were differences in the proportion of patients using additional analgesics and NRS according to the type of trocar, and the differences were more pronounced in females, which was consistent with previous reports. This study has some limitations. First, this is a retrospective study from a single center. Second, the total number of patients in the 3 mm trocar group was small; future studies should involve more cases of mini-laparoscopic surgery. Third, because the present study was analyzed retrospectively, we could not measure the size of the mini-laparoscopic umbilical incision. Fourth, we could not measure the actual amounts of opioid analgesics administered through PCA, and the types of additional analgesics were not consistent (Supplement Table, Supplemental Digital Content 1, http://links.lww.com/SLE/A406 ). In addition, we did not confirm the impact of 3 mm trocar use on PONV, which is the side effect of opioid analgesics. Fourth, we could not measure the cosmetic effect the of 3 mm trocar. In a future prospective study, by collecting the amount of PCA used, the PONV, and controlling the type of additional analgesics, we could clearly confirm that the 3 mm trocar can reduce postoperative pain and the side effects of opioids. In addition, by measuring the patient and observer scar assessment scale score, we can confirm the cosmetic effect of the 3 mm trocar.