Purpose
The purpose of the article was to review the thirteen years of experience and evaluate the usefulness of open inguinal hernia repair (OIHR) with transinguinal laparoscopic exploration of contralateral groin (TILE), the prevalence of contralateral patent processus vaginalis (CPPV), and the incidence of metachronous inguinal hernia after negative laparoscopic examination in pediatric patients with unilateral inguinal hernia.
Methods
We analyzed data from children aged 15 years and younger who underwent inguinal hernia repair between 2007 and 2019. We performed an OIHR with TILE to assess the contralateral groin, and TILE was accomplished via ipsilateral hernia sac. We collected the medical records and analyzed demographics, operation-related information, including the prevalence of CPPV and the incidence of metachronous contralateral inguinal hernia (MCIH).
Results
Of the 1,702 patients with unilateral inguinal hernia, 440 patients (25.9%) had CPPV. The risk factors of CPPV were younger age, female, and left inguinal hernia. The operation results of OIHR with TILE, such as postoperative pain, cosmetic results, recurrence rate, and recovery time was similar to other reports, including open and laparoscopic repair, if not better than LIHR. There were no complications associated with transinguinal laparoscopic exploration. Also, 28 patients (2.2%) with obliterated PV still developed an MCIH later.
Conclusion
OIHR with TILE is valuable and safe to detect CPPV in the laparoscopic era. There has been some development (2.2%) of MCIH after negative laparoscopic exploration, which suggested that even though PPV is a significant risk factor for developing a pediatric inguinal hernia, other factors also might be involved in the pathophysiology of pediatric inguinal hernia. OIHR with TILE may be a good surgical option because it compensate for the weakness of OIHR alone and has some advantages of LIHR alone. Two methods can also complement each other and might be tailored to the particular needs of individual patients.

Purpose
Ovarian mucinous cystadenocarcinoma is rare in adolescent population and reports are scarce in Korea. The aim of this study was to identify the clinicopathologic features and prognosis of adolescent ovarian mucinous cystadenocarcinoma.
Methods
Adolescent patients who were diagnosed with ovarian mucinous cystadenocarcinoma between 2001 and 2012 in Seoul National University Children Hospital were included. We retrospectively reviewed medical records of demographics, preoperative evaluation, tumor characteristics, and prognosis of patients.
Results
Among 5 patients, none of them reported family history of cancer or underlying disease relevant to malignancy. The median follow-up period was 13.3 years. The mean age at the time of diagnosis was 15.4 years. The mean size of the tumor was 26 cm. Only one patient had neoadjuvant chemotherapy. All patients underwent surgical treatment. One patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy for cytoreductive surgery and 4 patients underwent fertility sparing surgery. Three patients had platinum-based adjuvant chemotherapy. One patient suffered recurrence and eventual death and 4 patients are in disease free survival status.
Conclusion
Although ovarian mucinous cystadenocarcinoma in adolescent is rare, we should suspect the presence of it in case of adolescent intraabdominal large mass. As adolescent patients undergo fertility preserving surgery, serial and careful follow-up is necessary.

Purpose
The aim of our study was to provide informative data for surgically treated preterm infants with incarcerated inguinal hernia (IH) in the neonatal intensive care unit (NICU).
Methods
Medical records of 9 preterm infants in NICU who underwent IH repair before NICU discharge between January 2011 and June 2020 were reviewed. The definition of incarcerated IH used was irreducible IH even by pediatric surgeon regardless of the use of sedation. The incarceration rate was calculated and informative data for incarcerated IH patients were collected.
Results
Of 237 IH patients, 9 were diagnosed with an incarcerated IH and underwent emergency repair. At diagnosis of IH, the median age, the median postmenstrual age, and the median body weight were 22 days, 29.7 weeks, and 1,090 g, respectively. The diagnosis interval from IH to incarceration was ranged from 6 to 51 days, and none of them died of surgical procedure-related complications. Strangulation occurred in 4 patients and was treated with small bowel resection and enterostomy.
Conclusion
This study provided informative data for incarcerated IH in preterm infants successfully treated surgically. Close observation is more necessary because the incarceration rate during observation of preterm infants with IH in the NICU is as high as 3.8%.

Purpose
Thoracoscopic repair of congenital diaphragmatic hernia (CDH) is technically challenging and requires various surgical strategies. However, studies investigating the learning curve of thoracoscopic repair of CDH are rare. The
objective
of this study was to determine whether there is a learning curve of thoracoscopic repair of CDH and analyze its pattern by cumulative sum (CUSUM) analysis.
Methods
From 2008, when the first case was performed, to 2020, children diagnosed with Bochdalek-type CDH who underwent thoracoscopic repair were included. Learning curves of 2 operators were analyzed individually using the CUSUM method which is the running total of differences between operation time of each case and the mean operation time. We divided the CUSUM curve into three phases based on its slope and performed interphase analysis of patients’ baseline characteristics and surgical outcomes.
Results
A total of 111 children (operator A, n=88; operator B, n=23) underwent thoracoscopic repair of CDH during the study period. CUSUM curve of operator A showed an ascending curve from the first case to the 33rd case, then a plateau between the 34th case and the 55th case, and a descending form from the 56th case. In interphase comparisons of surgical outcome of operator A, recurrence rate and rate of complication did not show statistically significant differences. The learning curve of operator B showed a flat overall appearance and plateaued after the 14th case.
Conclusion
Surgical experience based on 33 cases was needed to reach the learning curve to perform thoracoscopic repair of CDH. For a new surgeon experienced with assisting a skilled operator, a relatively high proficiency was obtained from the start with a shorter learning curve. Interphase analysis of surgical outcome suggests that thoracoscopic repair of CDH can be performed without compromising patients’ safety even before reaching the learning curve.

Purpose
Kidney transplantation (KT) in small children is known to be associated with increased risk of surgical complications that may potentially lead to graft loss. KT in children weighing 15 kg or less are considered to be most technically challenging. We present our transplant center's experience with KT in this cohort of children.
Methods
We retrospectively reviewed our transplant center's KT database from January 1994 to July 2019. Recipients’ and donors' data were collected for analysis.
Results
From January 1995 to July 2019, 69 cases of KT were performed in recipients ≤18 years. We identified 9 children (11.8%) who weighed ≤15 kg at the time of KT. There were 4 boys and 5 girls. Median age of recipients was 4.0 years (range 16 months–7 years). Median weight at KT was 14.0 kg (range, 11–15 kg). 3 cases were living-donor KT and 6 cases were deceased-donor KT. Median weight of the kidney allograft was 106 g (range, 65–235 g). The allograft was implanted intraperitoneally in 6 cases and extraperitoneally in 3 cases. Postoperative vascular complication occurred in 1 patient (arterial anastomosis stenosis). Graft loss occurred in 2 patients, due to renal artery stenosis and chronic allograft nephropathy. Graft survival was 88.9% and 88.9% at 1 and 5 years, respectively. Mean followup was 91.6 months. Graft survival of children who weighed ≤15 kg at the time of KT was not different compared to children who weighed more than 15 kg.
Conclusion
KT in small children weighing ≤15 kg is technically challenging. However, with comprehensive care by a pediatric transplant specialist, these challenges may be overcome and lead to good transplant outcomes.

Intussusception recurs in 10% to 20% of childhood intussusception after successful nonoperative reduction. Multiple recurrences of intussusception are associated with the presence of a pathologic lead point. We describe a case of a 9-month-old boy with 4 times recurrent intussusception after nonoperative reduction caused by diffuse large B cell lymphoma lesion of the ileum. Clinical suspicion and surgical approach is needed to find rare cause of recurrent intussusception.