Indigo Carmine Dye–Assisted Lymphatic-Sparing Microsurgical Subinguinal Varicocelectomy Among Children and Adolescents

The purpose of this study is to clarify the safety and efficacy of indigo carmine dye–assisted lymphatic-sparing microsurgical subinguinal varicocelectomy for children and adolescents in our institution. Medical records of boys aged ≤ 15 years who underwent varicocelectomy between November 2008 and December 2019 at our institution were retrospectively reviewed. Microsurgical subinguinal varicocelectomy was performed using indigo carmine injection under the tunica vaginalis to preserve lymphatics. A total of 29 patients underwent varicocelectomy, among whom six underwent retroperitoneal high ligation (modified Palomo technique), nine underwent laparoscopic varicocelectomy, and 14 underwent microsurgical subinguinal varicocelectomy. The median operative time for retroperitoneal high ligation, laparoscopic varicocelectomy, and microsurgical subinguinal varicocelectomy was 71 (IQR: 59–82.5) min, 131 (95–151) min, and 125.5 (112–134.25) min, respectively. Among the patients who underwent laparoscopic varicocelectomy, one and two experienced hydrocele and varicocele recurrence as postoperative complications, respectively. None of the patients who underwent microsurgical subinguinal varicocelectomy developed hydrocele and varicocele recurrence during 15.5-month median follow-up period (IQR: 11.25–25.75 month). Indigo carmine dye–assisted lymphatic-sparing microsurgical subinguinal varicocelectomy can be a safe and efficient treatment modality among children and adolescents.


Introduction
Varicocele is defined as the excessive dilatation of the pampiniform venous plexus of the spermatic cord [1]. Studies have reported that the prevalence of varicoceles among adolescents is 35% for all grades and 15-25.8% for grades II and III [2]. Although no controversy exists regarding the therapeutic indications against painful varicoceles, debates on the surgical indications for varicoceles among children and adolescents have continued due to concerns regarding future fertility preservation and testicular asymmetry. Paternity and fertility outcomes have remained unclear following varicocelectomy for adolescent varicoceles [3]. Although patients would indeed benefit from early treatment, no tool has been available for determining those who would benefit from repair during adolescence.
Several surgical techniques for varicocele repair are available, including open inguinal (Ivanissevich technique) or retroperitoneal high ligation (original and modified Palomo technique), laparoscopic varicocelectomy, microsurgical subinguinal or inguinal varicocelectomy, and radiologic techniques, such as sclerotherapy and embolization [4]. However, microsurgical subinguinal varicocelectomy (MSV) has not been widely performed for children and adolescent patients, because no gold standard method for varicocelectomy among children has been established [5]. Possible reasons may include the lack of familiarity with surgical microscopy and expectations of greater procedural difficulty during surgery among pediatric patients due to the complex entanglement of the smaller vasculature [5]. On the other hand, MSV has become the gold standard treatment for male patients suffering from infertility due to varicoceles.
Postoperative hydrocele has been a potential problem among children and adolescents who undergo varicocelectomy, with incidence rates ranging between 0 and 32% [6]. Hydrocele following varicocelectomy occurs due to disruptions in lymphatic outflow from the tunica vaginalis upon vessel ligation. To prevent hydrocele formation, dye-assisted lymphatic-sparing varicocelectomies have been performed using various surgical methods (i.e., methylene blue, isosulfan blue, and indigo carmine) [5,7,8]. However, no study has yet been conducted on MSV using indigo carmine among pediatric and adolescent patients.
The aim of this study was to clarify the efficacy and the complications of MSV with indigo carmine for pediatric and adolescent patients with varicoceles and to compare those of laparoscopic varicocelectomy and retroperitoneal high ligation.

Patients
The study was approved by our institution's ethics review board . Medical records of boys aged ≤ 15 years who underwent varicocelectomy between November 2008 and December 2019 at our institution were retrospectively reviewed for age, indications for surgery, varicocele grade, surgical method, anesthesia method, laterality of surgical site, operative time, complications, preservation of the inner spermatic artery and lymphatic vessels in the spermatic cord, varicocele recurrence, length of hospital stay after surgery, pain resolution rate, and median follow-up period. Varicoceles were primarily diagnosed by physical examination with the patient in an erect position. The varicoceles were graded from I to III according to severity [9]. All the findings were confirmed by color Doppler ultrasound. Testicular asymmetry is defined as sonographically derived volume differentials greater than 20% [10].

Surgical Indications and Methods
The indications for varicocelectomy included (i) clinical varicoceles associated with ipsilateral testicular asymmetry; (ii) scrotal pain related to clinical varicoceles; and (iii) parental preference. Generally, the surgical method for varicocelectomy was determined based on the period, i.e., from November 2008 to February 2010, retroperitoneal high ligation was selected; from December 2009 to August 2015, laparoscopic varicocelectomy was selected; and since November 2016, MSV was performed. The period of use of high ligation and laparoscopic varicocelectomy partially overlapped. All surgeries were performed under general anesthesia.
During retroperitoneal high ligation and laparoscopic varicocelectomy, the internal spermatic artery was preserved (modified Palomo technique) similar to that described by Pintus et al. [11]. MSV was performed using a surgical technique similar to that described by Mehta et al. 12]. To spare lymphatics, approximately 2 ml of indigo carmine was injected under the tunica vaginalis after spermatic cord dissection [5]. The indigo carmine that is used is Indigo carmine Daiichi Sankyo (DAIICHI SANKYO COMPANY, LIMITED, Tokyo, Japan). Immediately after injection, the lymphatic vessels were stained blue ( Fig. 1). A surgical microscope (Leica M525 OH4, Leica Microsystems GmbH; Wetzlar, Germany) and Doppler probe (DVM-4500, Hadeco, Inc.; Kanagawa, Japan) were used during spermatic cord dissection to identify and preserve the testicular artery and lymphatics. A total of four surgeons performed MSV.

Statistics
Student's t-test was used for continuous data, and Fisher's exact test was used for categorical data. All statistical analyses were performed using the JMP Pro version 14.0 software (SAS Institute Inc., Cary, NC, USA), with a p-value of 0.05 considered to represent a significant difference.

Results
A total of 29 patients underwent varicocelectomy, among whom six underwent retroperitoneal high ligation, nine underwent laparoscopic varicocelectomy, and 14 underwent MSV. Patients who underwent retroperitoneal high ligation, laparoscopic varicocelectomy, and MSV had a median age of 12 (IQR: 11.25-12.75) years, 11 (IQR: 11-12) years, and 12.5 (IQR: 12-13.75) years, respectively. All varicoceles requiring treatment were located on the left side. Among the included patients, 8, 17, and 2 had grade III, II, and I varicoceles, respectively. Scrotal ultrasonography was used to objectively determine discrepancies in testicular size. Indications for varicocelectomy included (i) clinical varicoceles associated with ipsilateral testicular asymmetry (21 patients); (ii) scrotal pain related to a clinical varicocele (two patients); and (iii) parental preference (six patients). The median operative time for retroperitoneal high ligation, laparoscopic varicocelectomy, and MSV was 71 (IQR: 59-82.5) min, 131 (95-151) min, and 125.5 (112-134.25) min, respectively, with the retroperitoneal high ligation group having a significantly shorter operative time than the MSV group (p < 0.0001). The internal spermatic artery was preserved in 5, 4, and 12 patients who underwent retroperitoneal high ligation, laparoscopic varicocelectomy, and MSV, respectively. Lymphatic sparing was performed in all patients who underwent MSV. Other surgical procedures were performed without the intention to preserve lymphatics. Patients who underwent retroperitoneal high ligation, laparoscopic varicocelectomy, and MSV had a median postoperative follow-up period (IQR) of 11 (7.5-52), 11 (28-36), and 14 (11.25-23.75) months, respectively. All cases whose surgical indication was orchialgia achieved pain abrogation. During the follow-up period, postoperative complications developed in three patients: varicocele recurrence (two patients) and hydrocele (one patient). All postoperative complications occurred in patients who underwent laparoscopic varicocelectomy. None of the patients developed postoperative testicular asymmetry. All patients who underwent retroperitoneal high ligation and laparoscopic varicocelectomy were discharged the day after surgery. Among those who underwent MSV, 12 (85.7%) and 2 (14.3%) were discharged the day after surgery and on the second postoperative day, respectively. Two patients who were discharged on postoperative day 2 had their discharge postponed due to nausea (Table 1).

Discussion
Among the multiple techniques for varicocele treatment among adults and children or adolescents presented in the literature, MSV has been considered the best given its high success rates and low complication rates [6]. Despite being generally performed as a standard treatment for adult male patients with infertility [12,13], MSV as a treatment for pediatric and adolescent varicoceles does not share the same renown. This can be attributed to the unfamiliarity of general and pediatric urologists with surgical microscopes [14], which leads to stagnation in terms of the number of microsurgical operations being performed despite previous studies suggesting the usefulness of MSV for adolescent varicoceles. Many pediatric hospitals are public, and their plastic and neurosurgery departments usually have surgical microscopes. Thus, the pediatric urologist in Japan is well-equipped to perform MSVs, if the operation method is mastered. There is little equipment investment required to begin the surgical procedure. However, surgeons beginning MSV have expressed concerns regarding the microsurgical technique and control of postoperative complications. Accordingly, indigo carmine dye-assisted lymphatic-sparing MSV may help reduce incidences of complications.
Hydrocele development can be a potential complication following varicocelectomy. The low incidence of hydroceles following microsurgical varicocelectomy can be attributed to the preservation of lymphatic vessels. Given that the current study performed retroperitoneal high ligation and laparoscopic varicocelectomy without the intention to preserve the lymphatic vessels, hydrocele had been observed in one patient (11.1%) who underwent laparoscopic varicocelectomy. In a review of previous reports, the incidence of hydrocele after MSV for varicocele has been reported to be 0-0.07% in adult patients [15]- [16] and 2-3% in adolescent patients [17]. Although the rate of hydrocele after MSV has been low, it is necessary to preserve the lymphatic vessels and reduce the incidence of hydrocele even further; prevision studies have suggested the use of dyes, such as isosulfan blue and methylene blue, during MSV [18]. Although prior studies have also reported the use of indigo carmine in laparoscopic varicocelectomy [5], to the best of our knowledge, no previous literature had been available on indigo carmine-assisted lymphatic-sparing MSV. Indigo carmine allows for better visibility and easier identification of lymphatic vessels by inexperienced physicians. Though the lymphatic vessels can be identified without staining during MSV, small lymphatic vessels could potentially be missed. The indigo carmine dye-assisted lymphatic-sparing MSV was useful in preventing hydrocele development to a great extent. Indigo carmine injections under the tunica vaginalis of the testis rapidly stain lymphatic vessels in the spermatic cord and can thus be conveniently performed before external fascia incision. In the present study, lymphatic vessel preservation was achieved in all of MSV cases. During the follow-up period, none of the patients who underwent MSV developed hydroceles. Despite the small number of cases included herein, hydrocele formation had not been observed after surgery; this observation was similar to previous reports on dye-assisted lymphatic-sparing MSV [18]. Compared to previous reports on adult males, the current study had an obviously longer operative time considering the pediatric and adolescent patients who have smaller sized spermatic cord structures. Another reason may be that the surgeries performed herein were guided by a physician unfamiliar with microsurgery. Despite surgeon unfamiliarity with microsurgery, indigo carmine dye-assisted lymphatic-sparing MSV promoted easier lymphatic vessel preservation and allowed surgeons to perform varicocelectomy without fear of complications.
There are some limitations to this study. Firstly, the patient number is small. Second, the study was a retrospective investigation. As such, a high-quality, large-scale prospective study is warranted in the future. Third, we were unable to investigate the incidence of complications in the control group, i.e., the group without indigo carmine. Randomized controlled trial is warranted in the future.
In conclusion, the present study showed that indigo carmine dye-assisted lymphatic-sparing microsurgical subinguinal varicocelectomy is a safe and efficient treatment modality for children and adolescents and the technique is advised especially for beginner surgeons because it is practical and simple. The authors recommend the usage of indigo carmine routinely during microsurgical subinguinal varicocelectomy in all cases.
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