The impact of laparoscopic versus open inguinal hernia repair for inguinal hernia treatment: A retrospective cohort study

Abstract Objectives Although laparoscopic inguinal hernia repair (LIHR) has been widely accepted for treating inguinal hernia, the procedure remains very technical and challenging. The present study aimed to assess the effect of LIHR in relation to operation time, intraoperative hemorrhage and postoperative hospitalization. Methods A total of 503 patients with inguinal hernia admitted at the Wuxi Rehabilitation Hospital between June 2019 and July 2021 were included in this retrospective cohort study. Binary logistic and linear regressions were used for categorical and continuous outcomes, respectively. The learning curve was drawn by cumulative sum analysis. Results Multivariate logistic regression analysis identified LIHR as an independent factor associated with prolonging operation time (odd ratio [OR] = 1.750, 95% confidence interval [CI]: 1.215−2.520, p = 0.003) and decreasing intraoperative hemorrhage levels (OR = 0.079, 95 CI: 0.044−0.142, p < 0.001). Multivariate linear regression identified LIHR (Coefficient = −0.702, 95% CI: [−1.050] to [−0.354], p < 0.001) as an independent factor for shortening postoperative hospitalization time. After learning curve, LIHR (OR = 1.409, 95% CI: 0.948 to 2.094, p = 0.090) no longer resulted as a risk factor prolonging operation time. Conclusions LIHR is an important independent predictive factor for decreasing intraoperative hemorrhage levels and shortening postoperative hospitalization time. Additionally, LIHR does not prolong operation time after the learning curve.

alcohol and hernias. 2 It has been reported that the frequency of inguinal hernia repair increases with age, that is, 0.25%−4.2% in 18−80 yearolds. 3 According to the anatomical relationship of the Hessel Bach triangle, an inguinal hernia can be divided into the direct inguinal hernia, indirect inguinal hernia and femoral hernia, where approximately 96% are inguinal hernias, 20% of them are bilateral. 4 Inguinal hernias are more common in men, while femoral hernias are more common in women. 5 People with inguinal hernias may report a bulge or mass in the groin that becomes bigger over time. Stretching or tearing of the hernia defect site or surrounding tissue may cause pain or fainting; yet, approximately 1/3 of patients tend to be asymptomatic. 6 Importantly, acute severe abdominal pain suggests that the hernia may be incarcerated, requiring urgent surgical treatment. 3 Generally, once an inguinal hernia is formed, surgery is the most effective treatment. Inguinal hernia repair, including minimally invasive surgery and traditional open surgery, is the most common procedure. Although laparoscopic inguinal hernia repair (LIHR) has been accepted worldwide for the treatment of inguinal hernia, there is still some controversy between LIHR and open inguinal hernia repair (OIHR). 7,8 Furthermore, the promotion of LIHR technology is based on surgeons overcoming the learning curve, otherwise patients may encounter increased cost, longer operating time, higher recurrence, and complication rates. 9,10 Since the early 1990s, when LIHR was first reported, 11 the LIHR has become a routine procedure due to the rapid development of minimally invasive surgical technology and the increasing precision of surgical instruments and equipment. At present, an increasing number of surgeons advocate LIHR as an alternative to OIHR, although the previous alternative to OIHR was the open anterior approach, which was extensively used worldwide for the repair of the majority of hernias. 12 For a long time, recurrence has been considered an important outcome measure of the quality of inguinal hernia repair. Recurrence rates after OIHR were reported to be as high as 6.3% versus 6.5% after LIHR. 13 However, it was also reported that LIHR has advantages compared to OIHR approach in view of postoperative pain, time needed to return to work, and chronic inguinal pain. 14 Even so, its potential has not been fully used for the benefit of the patients. Although unilateral inguinal hernias may be controversial, the benefit of LIHR over open repair is well-established in patients with bilateral or recurrent inguinal hernias, and current guidelines recommend minimally invasive surgical repair for such cases. 15 Furthermore, the use of LIHR is not agerestricted, so elderly patients can also benefit from this approach, as previously reported. 16

| Surgical technique
All surgeries were completed by the same surgical team. Surgical procedures for LIHR and OIHR were performed as previously published. [18][19][20] In this study, LIHR was performed as transabdominal preperitoneal procedure (TAPP), whilst OIHR was performed as Lichtenstein techniques.

| Data collection
Data collection and follow-up were carried out for both LIHR and OIHR groups. Following data were included: age, medical history, hernia sac diameter, gender (M/F), type of hernia (Indirect/direct hernia), operation time, intraoperative hemorrhage, and postoperative hospitalization.

| Characteristics of the patients
A total of 578 patients with primary unilateral inguinal hernias diagnosed as inguinal hernia at Wuxi Rehabilitation Hospital were initially identified. Among 578 patients, 5 were excluded due to anesthesia intolerance, and 62 were excluded due to recurrent hernia combined with second surgery treatment. A total of 220 patients were treated with LIHR; 8 were excluded because they converted from LIHR to OIHR. Finally, 503 patients, 212 treated with LIHR and 291 treated with OIHR, were included in this study ( Figure 1). Significant differences were observed in age, medical history, Type of hernia (Indirect or direct hernia) and ASA Grade (I/II/III) (all p < 0.01, Table 1) between OIHR and LIHR groups, while there were no differences in gender and hernia sac diameter (all p > 0.05, Table 1).

| Potential effect factors associated with operative time
As shown in Table 1

| Potential factors influenced operative time and intraoperative hemorrhage levels after the learning curve
It is well known that the proficiency of operation has an impact on operative time and intraoperative hemorrhage levels. 21 Hence, CUSUM analysis was performed to plot learning curve for LIHR.
As shown in Figure 2, during the 54th case, the trend of CUSUM Since the first LIHR, 11 this approach has been associated with various advantages such as less trauma, reduced postoperative pain and wound infection, as well as less time needed to return to work, etc. Patients with inguinal hernia could benefit from LIHR, considering it is the minimally invasive surgery for treating inguinal hernia. 22 Herein, we assessed the advantages and disadvantages between LIHR and OIHR. Compared with LIHR, OIHR had a shorter operation time. Statistical analysis suggested that LIHR was an independent factor for prolonged operation time in the treatment of inguinal hernia (Table 2), which was consistent with a previous study. 16  shown that the LIHR technique requires a certain learning curve for the surgeon, and patients also need to undergo general anesthesia. 25 When surgeons overcome their learning curve (previously reported range from 50 to 250 cases, 26 which was in line with our study of 54 cases, Figure 2), the potential advantages of LIHR, such as faster recovery, reduced pain and recurrence rates, and similar will be more effective. 9 Even though there was no recurrence of hernias at our medical center between June 2019 and July 2021, the same surgical group completed all of the operations. Numerous studies have shown that LIHR was similar to OIHR in terms of recurrence rates 27 ; however, longterm follow-up data are still needed. Previously, LIHR of primary inguinal hernias in women was associated with lower reoperation rates and less recurrence of femoral hernias than the OIHR approach. 13 It has also been reported that untreated lipoma is the main cause of recurrence after laparoscopic repair, so any lipoma in the inguinal region must be clearly dissected during the LIHR. 28 Several technical factors, such as mesh size, improper fixation, and missed hernias, are generally considered the main causes of recurrent hernias in OIHR and LIHR. 12 In addition, insufficient medial/lateral fixation of the mesh, and omission of lipomas and hernias through mesh slits are also factors for hernia recurrence. Likewise, insufficient separation and overlap of myopectineal orifice, mesh folding, and hematoma-induced dislocations have also been suggested as factors affecting hernia recurrence. 29 Therefore, the LIHR approach should be implemented by experienced surgeons. 12 To carry out the correct procedure of LIHR, the surgeons must understand the anatomical structure of the Myopectineal Orifice, 12

| Study limitations
The present study has some limitations, like a comparison of the treatment of unilateral inguinal hernias. In addition, more feedback from patients undergoing this procedure is needed. Also, this was a retrospective study, so large data samples and prospective studies may better characterize the association between hernia sac diameter, medical history, surgical method, operation time, intraoperative hemorrhage and length of stay. Moreover, long-term follow-up was not performed. Furthermore, patients were mainly from nearby of Wuxi City, Eastern China, and there was a lack of multi-center and/or regional comparative analysis.

DATA AVAILABILITY STATEMENT
The datasets used and/or analyzed during the current study are available from the corresponding author (Chaobo Chen) upon reasonable request.
For any queries, kindly contact bobo19820106@gmail.com.

ETHICS STATEMENT
This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of the Wuxi Rehabilitation Hospital (No. wxkf20220618).
The need for individual consent was waived by the committee.

TRANSPARENCY STATEMENT
The lead author Chaobo Chen affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.