Purpose
Pediatric surgical activity is an important factor for a hospital manager when considering to hire a new pediatric surgeon. The purpose of this study was to investigate the activity of pediatric surgeons by comparing the number of surgeries and local population trends over the history of the institution, and to predict the potential demand for pediatric surgeons in the future.
Method
The annual number of surgeries performed at the Department of Pediatric Surgery of Ajou University Medical Center from May 1994 to December 2018 was investigated. In addition, the total and pediatric populations and demographic trends in Suwon and Gyeonggi-do and nationwide trends were examined, and the change in the number of surgeries performed annually was compared with the total and pediatric populations. Predictive model of future population in the region was created with logarithmic regression.
Results
The average annual number of operations was 539, and neonatal surgeries consisted 6% of all surgeries. The proportion of children in the total population in Gyeonggi-do decreased from 30% (1995) to 17% (2018) and from 31% (1995) to 17% (2018) in Suwon. In 2018, Suwon's population increased by 454,556 compared to that in 1995, but the decrease in the children's population seems to reflect the decrease in the national total fertility rate over the past 25 years. The predictive model suggested an aggravation in the decrease of pediatric population in the region in the next 20 years, predicting a 41.86% decrease in Gyeonggi-do and a 55.15% decrease in Suwon compared to 2020.
Conclusion
According to the results, the number of cases of pediatric surgery has grown relatively, considering the decrease in the pediatric population which may aggravate in the future. These data may be used as indirect evidences for organizations to determine whether to hire new pediatric surgeons.

Purpose
Late presenting congenital diaphragmatic hernia (CDH) in children has various clinical manifestations and serious pitfalls in diagnosis, which make differentiation very difficult. Thus, we intended to identify the clinical manifestations and to build the proper strategy of diagnostic imaging for late presenting CDH on the base of our institutional experience.
Methods
We performed a retrospective review of medical records for 6 patients who received the operation for late presenting CDH from December 2003 to March 2018 in our hospital.
Results
The range of age was 55 days to 13 years and the ratio of sex (male:female) was 2:1. The most common symptom was vomiting, followed by abdominal pain, chest discomfort, dyspnea, and cyanosis. As an initial diagnostic imaging study, chest X-ray was performed in all patients, of whom one patient checked it after the insertion of a gavage tube. As a secondary additional imaging study, chest computed tomography (CT) was performed in 4 patients, abdominal ultrasonography was performed in 2 patients, and chest magnetic resonance imaging, abdominopelvic CT, renal scan were each carried out for 1 patient.
Conclusion
If late presenting CDH is suspected in initial chest X-ray of patient who has gastrointestinal or respiratory symptoms, chest X-ray after insertion of a nasogastric tube or additional imaging study such as chest CT should be checked.

Purpose
Pyloric muscle thickness (PMT) equal to or greater than 4 mm and canal length equal to or greater than 15 mm are used to be widely accepted for diagnosis of idiopathic hypertrophic pyloric stenosis (IHPS). However, up to 25% of IHPS patients show ultrasonic parameters discordant to current diagnostic criteria. The authors tried to look if previously suggested criteria could be applied to the IHPS patients of a single center and find new concepts by analyzing the ultrasonic parameters and patient characteristics.
Method
Medical records and ultrasonography (US) of 131 IHPS patients who received pyloromyotomy from 1994 to 2016 were reviewed. All presented with characteristic clinical symptoms. The patients were divided into 2 groups according to their eligibility for current criteria used in the authors' institution, as discordance group (n=32) and concordance group (n=99). Baseline characteristics were reviewed, and ultrasonic parameters were measured, and then the volume of pylorus was estimated by calculation using the measured parameters.
Results
The proportion of neonates was greater and the mean postconceptional age was younger in Discordance group than that of Concordance group at the time of US examination. Average weight at the time of US were lighter in discordance group than those of concordance group, as well. Also, mean pyloric volume (PV) and proportion of PMT/pyloric diameter were lesser in discordance group (1.72±0.49 mL vs. 2.98±0.87 mL and 31.87%±3.24% vs. 35.06%±3.61%, p<0.001), while mean luminal volume was similar in both groups. Postconceptional age and being neonate were significant variables for PV after multivariate linear regression (R ² =0.390).
Conclusion
The calculated PV of IHPS patients was strongly related to their postconceptional age, and it suggested that the diagnostic criteria may differ according to the patients' sizes and the time of their diagnoses. Future diagnostic criteria for IHPS should be applicable even with the dynamic nature of the patients.

In patients with Langerhans cell histiocytosis (LCH), it is possible for other malignancies to develop. In the majority of cases, these are lymphomas and leukemia; however, in some cases solid tumors such as lung carcinomas may exist concurrently or can develop after chemotherapy. We want to introduce a rare solid tumor that can be found during LCH treatment. A 4-year old boy who was treated for 15 months with chemotherapy for LCH. The mass was noted on a follow-up abdominal ultrasonography. He underwent an abdominal mass excision and it was confirmed as a ganglioneuroblastoma. Coexistence of malignant neoplasms with LCH is currently being studied but is not yet well understood. In this case report, ganglioneuroblastoma appeared after chemotherapy for LCH. Whether this solid tumor developed as a result of chemotherapy or was formed due to the inflammatory response of LCH is still controversial.

Sigmoid volvulus (SV) occurs due to the twist of a dilated sigmoid colon on its mesenteric axis, which can compromise the blood supply to the colon, leading to necrosis or perforation of the sigmoid colon. Potentially life threatening, SV is common in the elderly and rare in youth. We present the case of a 16-year-old boy who had experienced 3 episodes of SV over the course of a year and was successfully treated with laparoscopic-assisted sigmoid colectomy. SV should be considered when a young patient has a history of recurrent abdominal pain, constipation, and abdominal distension.

Among the 5 different Todani subtypes of choledochal cyst, type II choledochal cyst is known to be the rarest. A 13-month-old female who had underlying congenital portal vein stenosis and portal hypertension presented sudden hematemesis and abnormality in liver function test. Upon evaluation with a liver ultrasonography, a 1.7 cm-sized cystic lesion near the common bile duct and duodenum was incidentally discovered, and further imaging with magnetic resonance cholangiopancreatography, upper gastrointestinal series, computed tomography, and percutaneous transhepatic cholangiography revealed type II choledochal cyst. The patient underwent choledochal cyst excision with Roux-en-Y hepaticojejunostomy and had no acute postoperative complications.