In recent years, there has been a growing body of researches dedicated to ERCP in pediatric pancreatic-biliary diseases such as pancreaticobiliary maljunction (PBM) [7, 8], pancreas trauma [9], and pancreatitis [10]. Nevertheless, pediatric ERCP remains a challenge for endoscopists due to issues related to success rates, post-operative complications, and the required medical expertise [11]. Performing therapeutic ERCP in children, particularly newborns and infants, is consistently challenging due to limitations associated with their weight and available medical devices [12]. In this study, we successfully performed a therapeutic ERCP using the JF-260V duodenoscope on an infant weighing only 5.9 kg.

Several differences exist between pediatric and adult ERCP, including variations in indications, anesthesia methods, instrumentation, and procedural techniques. Pediatric patients undergoing ERCP invariably require general anesthesia due to their limited tolerance [12]. Centers conducting pediatric ERCP procedures must possess extensive expertise in pediatric anesthesia and perioperative management. Endoscopes with a larger outer diameter may compress the trachea and have an impact on the respiratory system under general anesthesia. Therefore, monitoring and adjusting respiratory parameters during anesthesia become critically important. Additionally, the digestive tract in children is both smaller and more vulnerable. This can potentially elevate the risk of tissue edema, bleeding, and perforation.

In the majority of ERCP centers, these procedures are carried out by gastroenterologists who primarily treat adult patients. While the procedure for pediatric ERCP closely resembles that of adult ERCP, the choice of equipment and therapeutic success rates can vary across different reports [13–17]. Variations in success and therapeutic rates may depend on the proficiency of centers in managing pediatric digestive diseases and their level of perioperative care. In our center, we have conducted nearly 500 pediatric ERCP procedures with a success rate exceeding 90%. Over 80% of the pediatric ERCPs performed at our center are therapeutic. Radan Keil and colleagues reported the largest cohort, comprising 856 ERCPs conducted on 626 pediatric patients, achieving a remarkable 96% technical success rate. Within this report, 59% of the ERCPs were therapeutic [18]. ERCP procedures in patients less than 1 year of age are primarily diagnostic, aimed at excluding biliary atresia [19]. In these cases, a PJF-160 duodenoscope is consistently selected for the ERCP procedure. Sanada et al. used a PJF-160 duodenoscope and special instruments to perform therapeutic ERCP on an infant weighing 5.8kg, achieving excellent results [20]. The PJF-160 duodenoscope is currently discontinued. Therefore, performing therapeutic ERCP on infants with low weight requires the use of adult duodenoscopes, undoubtedly increasing the procedural complexity (the comparison of parameters between PJF-160 and JF-260V is shown in Table 1). To our knowledge, this infant in this case represents one of the lightest patients to undergo successful therapeutic ERCPs using adult duodenoscope in published research. In multiple reports, conventional duodenoscopes were not recommended for patients under 1 year old or weighing less than 10 kg [16, 21]. In a previous study conducted by our team, we reported a series of ERCP procedures on 15 patients under 1 year of age using the JF-260V duodenoscope, with a therapeutic rate of 88.2%. The complication rate was 11.8% (two out of 17 procedures) [22]. All complications were successfully managed with conservative treatment. Therefore, therapeutic ERCP using a conventional duodenoscope can be safely conducted under stringent and well-defined indications. ID, Inner diameter; OD, Outer Diameter

Pediatric ERCP presents unique technical challenges. Owing to differences in the structure of the upper gastrointestinal tract between children and adults, advancing the duodenoscope during the ERCP procedure can be challenging. Particularly when the duodenoscope's body reaches the duodenum through the pylorus, the confined, narrow space poses challenges for rotating the distal end of the duodenoscope forward. Simultaneously, due to the shorter duodenum in children, the papilla is often not centrally positioned in the endoscopist's preferred field of view, frequently appearing in the upper part of the field. Furthermore, the curvature of the duodenoscope's distal end within the intestinal cavity is quite limited due to the constrained space, rendering it nearly parallel to the common bile duct (CBD). This configuration also presents challenges during cannulation and other procedures. Given the significant disparity in the disease profile between children and adults undergoing ERCP for diagnosis and treatment, pediatric patients frequently present with conditions such as PBM or congenital pancreatic duct malformations. The deep cannulation technique commonly employed in adult ERCP should not always be the primary choice for selective cannulation in pediatric patients, particularly those with PBM. Cannulation should be guided by contrast medium to prevent repeated entry into the pancreatic duct, thereby minimizing the risk of excessive damage to the delicate papilla in pediatric patients.

Based on the available literature, the incidence of complications following ERCP in children can vary between 6% and 10%, depending on the experiences of different medical centers [17]. A meta-analysis of complications following ERCP in children yielded an average complication rate of 6% [23], a figure comparable to the complication rate observed in adult ERCP procedures. Pancreatitis stands out as one of the most frequent postoperative complications [23]. Currently, the risk factors for postoperative complications following ERCP in children remain incompletely understood [24, 25]. Factors such as the experience of endoscopists, patient weight, age, choice of anesthesia method, and repeated entries into the pancreatic duct may represent potential risk factors for postoperative complications.

In this case, since the child exhibits signs of impending complete biliary obstruction, relieving the obstruction is the priority. ERCP serves both diagnostic and therapeutic purposes and is relatively minimally invasive, making it the preferred diagnostic and therapeutic approach for such patients. Besides alleviating obstruction, ERCP can also exclude surgical issues such as PBM and biliary atresia. However, considering that ERCP still has a certain false-negative rate in congenital pancreaticobiliary malformations and is more challenging in infants and young children, we may still opt for minimally invasive or open surgery when necessary. Additionally, while performing surgery, we can conduct bile duct exploration and relieve obstruction, as well as perform liver biopsy, to diagnose certain bile stasis-related diseases pathologically.

The diagnosis and treatment of this case also have certain limitations. We did not conduct the most comprehensive examinations to determine the definite causes of the patient's bile duct stones and possible hemolytic anemia. In the patient's future follow-ups, we will closely monitor the symptoms and signs and provide necessary further examinations.

In conclusion, therapeutic ERCP in pediatric patients has proven to be both safe and effective. As experience and techniques continue to evolve, it is feasible to consider implementing therapeutic ERCP procedures in low-weight infants using conventional duodenoscope. Furthermore, additional multi-center prospective studies are imperative to establish a consensus regarding the indications and standardized operating procedures for ERCP in children, particularly in the case of infant ERCP.