The meaning of laparoscopic procedure against inguinal hernia

Background Laparoscopic approach, especially laparoscopic percutaneous extraperitoneal closure (LPEC) for inguinal hernia (IH) is widely spread but few studies have compared its invasiveness with that of conventional approach (POTTS). This study compared the role and invasiveness of LPEC with POTTS at our institute.


Conclusion
LPEC can be performed to avoid contralateral recurrences; surgical time is reduced for patients aged < 1 year. However, the reduced invasiveness of LPEC compared to that of POTTS did not minimize postoperative symptoms or complications.

Background
Herniorrhaphy is one of the most conventional surgical procedures against inguinal hernia (IH) for pediatric surgeons [1]. Traditionally, open surgery has been performed for IH; however, laparoscopy is currently being explored [2] as a treatment option [2][3][4][5]. Laparoscopic percutaneous extraperitoneal closure (LPEC) was rst reported in 1995, and has gained popularity as being the standard treatment procedure for IH [6][7][8][9]. Its bene ts are: 1) con rming the contralateral patent processus vaginalis (CPPV), indicating contralateral side recurrence in the future, and 2) the cosmetic result of the process. LPEC has the disadvantage of a higher recurrence rate than in the open method [10]; however, it has great bene ts and, therefore, it is widely used.
Minimally invasive surgery (MIS) describes either a small incision or an approach not involving cutting tendons or splitting muscles. The bene ts include reduced pain, rapid resumption of routine activities, and lesser tissue damage compared to traditional surgeries [11]. In pediatric surgery, LPEC is included under MIS. Comparative studies have been performed between LPEC and conventional open surgery [7][8][9]; however, few papers have been analyzed with respect to the invasiveness of the procedure. For the evaluation of the invasiveness, various factors have been investigated, such as operation and anesthesia times, and postoperative pain. This study aims to compare the role and invasiveness of LPEC with conventional open surgery for pediatric IH.

Study design
This multi-center study included a retrospective review of 940 patients who underwent IH repair between January 2014 to December 2019 from two independent hospitals (Showa University Koto Toyosu Hospital Children's Medical Centre, Showa University Northern Yokohama Hospital Children's Medical Centre). The Potts (POTTS) method was employed for open surgery, and LPEC was adapted to laparoscopy. In both centers, the techniques of POTTS and LPEC against IH, were presented to patients with respect to their pros and cons, who determined the method of operation. Medical records were reviewed with respect to age, sex, operative method and time, average period of the oral intake, and pre and postoperative symptoms, diagnosis and complications.
The post-operative symptoms indicating the invasiveness of the operation and anesthesia were classi ed as "fever up" (over 38 degrees Celsius), "pain" (needing additional painkiller administration), and "vomiting" (post-surgery). All patients who underwent operation against IH were indirectly diagnosed.
Criteria for enrollment included indirect IH and associated hydrocele. Patients who underwent other procedures, like umbilicoplasty or orchidopexy, simultaneously as herniorrhaphy, were excluded. Patients were permitted oral intake at least 3 hours after operation; this was adjusted according to the condition by the nursing stuff. Patients were followed up in the outpatient clinic at 1 week and 1 month postoperatively, to assess the prevailing conditions and wound healing.

Statistical analysis and ethics
The distribution of continuous data was evaluated using the student's t-test, and categorical variables with the Chi-square test. A p-value less than 0.05 was considered statistically signi cant.
There are no con icts of interest to declare. This study protocol was approved by the Ethical Committee at Showa University. The procedures used in this study adhere to the tenets of the Declaration of Helsinki.

Surgical procedures
General anesthesia All operative procedures were performed under general anesthesia with an intra-tracheal intubation.
During the operation, 4-6 µg/kg of Fentanyl was administrated intravenously. For the POTTS group, local anesthesia comprising of 1.5-2 mg/kg of Ropivacaine was applied by the surgeon. For LPEC, Rectus Sheath Block was preoperatively applied using 1.5-2 mg/kg of Ropivacaine.

POTTS procedure
Open method for IH was performed as described by Potts et al; this is high ligation and removal of hernia sac. A skin incision was made on the lower abdominal wall, measuring approximately 1.5 cm. The external oblique aponeurosis was incised, as the ber direction and muscle layer were split. The hernial sac was identi ed and divided from the testicular vessels and spermatic cord in males. High ligation was performed by the double trans xation of absorbable suture materials of size 3-0. The uterine cord was ligated together in females. The hernial sac on the distal side was explored and opened. The closure of the fascia and skin was carried out, and the incision was covered by tape and glue.

LPEC procedure
Laparoscopic method for IH was performed, as described by Takehara et al [6]. The 3-mm trocar was inserted through the umbilicus for laparoscopy; a 2-mm trocar was inserted on the right side of the abdomen for the active port using grasping forceps. Pneumoperitoneum was maintained at a pressure of 8 mmHg, with a CO 2 ow rate of 1-3 L/min. Plying a unique needle (19G LAPAHER CLOSURE ® , Hakko Medical Co., Nagano, Japan), the internal inguinal ring was secured by a 2-0 non-absorbable suture, avoiding any peritoneal gap and injury of the testicular vessels and spermatic cord in males. In case the CPPV had been marked, closure should have been done at the same time. Closure of the peritoneum and fascia was performed for the umbilicus wound. Skin incision was covered by glue. In patients with hydrocele, the puncture procedure was added to the scrotum.
The operation time comparison for each age group is shown in Table 2. The mean operation time for patients aged <1 year was 42.7 minutes in the POTTS group, and 33.4 minutes in the LPEC group (p<0.05). Other age groups showed no signi cant difference of operation time between POTTS and LPEC.
The anesthesia time comparison in each age group is shown in Table 2. The mean anesthesia time for patients aged 1-5 years and 6-10 years were 75.6 min and 69.8 min in the POTTS group, against 83.5 min and 76.9 min in the LPEC group, respectively (p<0.05). In addition, the mean anesthesia time was 74.6 min in the POTTS group, and 81.8 in the LPEC group (p<0.05).
The postoperative invasiveness is indicated in Table 2. There was no signi cant difference of the postoperative time with respect to the oral intake in total, and in each age group between POTTS and LPEC. In the <1 year group, 21% and 10% of patients suffered fever up in the POTTS and LPEC groups, respectively (p<0.05). In the patients aged 1-5-years, 11% suffered from fever up in the POTTS group, and 18% did in the LPEC group, respectively (p<0.05). There was no signi cant difference of fever up patients in other age groups between POTTS and LPEC. In the patients aged 6-10-years, 16% suffered pain in the POTTS group, and 25% did in the LPEC group, respectively (p<0.05).
In total, 6.6% suffered pain in the POTTS group, and 18% did in the LPEC group, respectively (p<0.05). There was no signi cant difference in patients suffering vomiting in various age groups between the POTTS and LPEC groups.
The postoperative complications are shown in Table 3. Wound infections were observed in 0% patients in the POTTS group, and in 1.2% in the LPEC group (p<0.05). The recurrence rate was 0.8% in the POTTS group, and 1.8% in the LPEC group (p<0.05). Hematoma in wound, scrotum swelling, and cryptorchidism were dominantly observed in the POTTS group.

Discussion
The principle of surgical treatment for pediatric IH remains high ligation of the hernia sac at the internal inguinal ring. Open herniorrhaphy is considered the gold standard and the most performed surgical procedure in pediatric IH. Several laparoscopic IH repairs have been reported over the last decade. The advantages include a clear operative eld, prophylactic surgery of the contralateral side, and the prevention of injuries for vessels and the spermatic cord [12,13]. Comparing the methods between open and laparoscopic surgery, Alzahem reported meta-analysis in 2011 using 10 comparative studies [14].
Laparoscopic techniques were associated with a trend towards a higher recurrence rate, variable operative time for repairs, and a reduction in metachronous hernia development [14]. LPEC was reported in 1995, and has gained popularity as the standard procedure for IH [6]. Operative times were found to be shorter in LPEC [7,8]. Modi ed LPEC displayed a longer operative time than the open method, but no statistically signi cant difference was found in the recurrence rate [9]. We classi ed our data as per the age group; infant (< 0 year), toddler (1 to 5 years old), school child (6 to 10 years old), and adolescents (> 11 years old); operative easiness, tissue weakness, and expression of invasiveness affect the results in each group. No signi cant difference was reported in the operative time of the one-year-old group, but infants displayed a shorter operative time with LPEC than with POTTS. In infants, during POTTS procedure, the adipose tissue interferes with the distinct operative eld; the peritoneal hernia sac is so weak and thin that the dissection from the testicular vessels and spermatic cord require concentration rather than age. On the other hand, LPEC shows an identical operative eld and management independently of age. In the present study, the anesthesia time was signi cantly longer in the toddler and school child groups. Pneumoperitoneum at LPEC pressure of 8-10 mmHg requires deep sedation rather than POTTS; this prompts lengthier postoperative recovery.
Another bene t of the laparoscopic method is con rming CPPV [8,9]. There is a 5-20% chance of developing a contralateral hernia in pediatric patients [2]. Data suggest that the incidence of the contralateral metachronous inguinal hernia (CMIH) was signi cantly higher in the POTTS group than in the LPEC group. The propriety of this bene t is vague as CPPV is not always predictive of symptomatic CMIH. Studies reveal the risk of developing symptomatic IH with asymptomatic patent processus vaginalis [15,16]. Accordingly, laparoscopic operation develops symptomatic inguinal hernia, at the rate of 10.5-13%. These rates are relatively low; however, further studies in elderly individuals diagnosed with indirect hernia with CPPV in childhood are required.
MIS represents a term that describes either a small incision or an approach not involving cutting tendons or splitting muscles. Some centers employing laparoscopic method for IH believe this procedure is less painful, resulting in earlier recovery and improved appearance [17]. Many studies have been carried out comparing conventional open surgery and LPEC; however, few papers have compared for circumstantial invasiveness [14]. We measured the invasiveness of operation and general anesthesia by (1) mean hours to rst oral intake, (2) fever up, (3) pain, and (4) vomiting. In our results, no signi cant difference was observed in the mean hours to the rst oral intake and vomiting after operation. This means the recovery from general anesthesia is equal in both groups. In fever up, the longer operation time in infants should cause a signi cantly vaster effect of fever up in the POTTS group. LPEC had signi cant defects on fever up in the toddler group and pain in the school age group. The age group itself affected the mental characteristics of the patient; greater post-operative invasiveness is observed in patients with LPEC. As this evaluation of invasiveness is indirect and not quantitative, a more direct and quanti ed method should be utilized further, such as visual analogue scale.
Comparing the postoperative complications in our data, wound infection, especially in the umbilicus port site, was appealing in patients with LPEC. Miyake et al indicated the umbilicus lesion in LPEC contains much greater bacterium than the inguinal skin wound in patients with POTTS [9]. Hematoma, scrotum swelling, and cryptorchidism are dominant in the POTTS group. These are reasonable because LPEC never touches the scrotum; the peritoneum from testis vessels and spermatic cord are separated su ciently. Taylor et al describes the risk factors of recurrence in pediatric IH with a nationally representative cohort study. The incidence rate was the highest among children who underwent initial primary repair at the age of < 1 year [18]. Comparing the recurrence of IH between open and laparoscopic surgery, many papers indicate a higher recurrence rate for laparoscopy [13,19,20]. However, Parelkar et al indicated technical modi cations that they were capable of reducing the recurrence rate from 2.9-0% HS contributed to study concept and design, analysis and interpretation of the data, and was a major contributor in writing the manuscript. JY, AS, TN, and YW contributed to data analysis and interpretation. All authors read and approved the nal manuscript.