Choledochal cyst (CC), also known as congenital biliary dilatation, is a congenital malformation characterized by cystic or spindle-shaped dilatation of the bile ducts. The incidence of CC is significantly higher in Asian children than in Western populations, with an estimated occurrence of approximately 1:100,000–150,000 live births (1–3). Additionally, the condition is more common in females, with a male-to-female ratio of 1:3 to 1:4. More than 60% of cases are diagnosed before the age of 10 years (4). If left untreated, CC can lead to severe complications, including cholangitis, pancreatitis, cystic perforation, and even bile duct cancer (5, 6). Acute cholangitis is a relatively common complication of CC, presenting symptoms such as fever, jaundice, abdominal pain, and a systemic inflammatory response. The symptoms are often mild and can be improved with conservative treatment. However, some children may present with severe symptoms at onset or experience symptoms progression despite conservative management. For these patients, urgent biliary decompression is critical to prevent severe sepsis or bile duct perforation (7–9).

The primary treatment for CC complicated by severe cholangitis involves biliary drainage. Conventional external biliary drainage (CED), which includes T-tube drainage, percutaneous cystocentesis, and cholecystostomy, is commonly used. However, these techniques are associated with significant drawbacks, including incisional pain, scarring, and complication rates of up to 25%, with risks such as incisional infection and intestinal adhesions (7, 10). While radical surgery, including Roux-en-Y hepaticojejunostomy, is the definitive treatment for CC, acute inflammation often necessitates temporary biliary drainage as a transitional measure (11, 12). Cyst excision and biliary reconstruction can be particularly challenging due to the risk of intraoperative bleeding and postoperative complications, including difficulties with infection control and anastomotic failure.

Endoscopic retrograde cholangiopancreatography (ERCP) is widely used as a diagnostic and therapeutic tool for pancreaticobiliary disorders in adults and has also proven effective and safe in pediatric patients (8, 13–17). While endoscopic biliary drainage (EBD) is well-established in adults, its use in pediatrics remains limited due to technical challenges, equipment constraints, and a lack of specialized expertise (17). Moreover, there is no study comparing the efficacy of EBD and CED in the treatment of children with CC complicated by severe cholangitis.

In this study, we used endoscopic nasobiliary drainage or stent placement between the dilated common bile duct and the duodenum to facilitate bile drainage in children with CC complicated by severe cholangitis. The study aimed to systematically compare the clinical efficacy and safety of EBD with CED in treating pediatric CC complicated by severe cholangitis and to provide an evidence-based foundation for optimizing treatment protocols.

Acute biliary tract infection is one of the most common complications of CC. In children with CC and severe biliary infections, external drainage is typically indicated when the condition cannot be controlled with a short period of conservative treatment (7–9, 16, 21, 22). Emergency external biliary drainage is recommended as a Phase I intervention, followed by definitive Phase II surgery. Traditional extracorporeal drainage methods, including open or laparoscopic biliary T-tube drainage, gallbladder drainage, and percutaneous cystocentesis drainage, are commonly used after the acute phase has subsided (9, 21, 22). These techniques usually provide immediate symptomatic relief and help reduce biliary inflammation. However, they have significant drawbacks, including painful incisions and the potential development of infections and adhesions in the surrounding tissues, which can increase the difficulty and risk of subsequent radical surgery (22).

The EBD overcomes many of the disadvantages associated with traditional external drainage. The ERCP with nasobiliary or stent placement drainage has been widely used to manage adult pancreaticobiliary diseases. However, using ERCP in children remains limited, primarily due to the lack of specialized pediatric endoscopist equipment for children and the limited experience of pediatric endoscopists (17). Additional challenges include the relatively low prevalence of conditions requiring ERCP in childhood and the perception that the procedure is technically difficult in children (8). Recently, advancements in pediatric duodenoscopy techniques have led to increased research on using ERCP for choledochal cysts and severe cholangitis in children. Tsuchiya et al. (8, 15) concluded that endoscopic stenting is an effective treatment for children with persistent or worsening symptoms of CC. We have successfully applied ERCP for early-stage choledocholithiasis and chronic pancreatitis in children and are gaining additional experience (23). In this study, we performed ERCP with stenting and nasobiliary drainage in children with severe cholangitis caused by CC, achieving favorable clinical outcomes consistent with Sun et al. findings (16).

In this study, we systematically compared the clinical efficacy and safety of EBD with CED in children with CC complicated by severe cholangitis through a retrospective cohort analysis. The results indicated that EBD outperformed CED regarding surgical efficiency (operative time, intraoperative bleeding), postoperative recovery (length of stay, pain scores), and complication control. These findings confirm the feasibility of using endoscopic techniques in pediatric patients with biliary disorders and provide crucial evidence for optimizing transitional treatment strategies for severe cholangitis in CC.

In this retrospective cohort, the operative time in the EBD group (median 29 min) was significantly shorter compared to the CED group (median 65 min), and intraoperative bleeding was nearly negligible (0 vs. 5 ml), a finding that aligns with recent trends in the development of endoscopic techniques in pediatric patients. Studies in adults have indicated that ERCP-guided biliary drainage avoids open surgery and trauma to the abdominal cavity or bile ducts by utilizing the natural lumen, significantly reducing operative time and minimizing intraoperative bleeding risk (1). However, the application of EBD in pediatric patients has been limited due to difficulties, including smaller anatomical structures, lack of specialized equipment, and insufficient experience (17). This study successfully achieved efficient biliary drainage in children using adult-sized ERCP equipment combined with standardized operating procedures.

The minimally invasive nature of EBD also had a direct impact on the postoperative recovery process. The EBD group exhibited a significantly shorter postoperative hospital stay than the CED group (P < 0.001). Additionally, the FLACC pain score in the EBD group was lower (median 2) compared to the CED group (median 4) at 24 h postoperatively, and the CED group exhibited a longer hospital stay (median 12 days). This difference can be attributed to the invasive nature of CED surgery, whether open or laparoscopic, which causes greater tissue damage and triggers a stronger inflammatory response. In contrast, EBD is performed through the natural lumen of the endoscope, avoiding abdominal wall incisions and intra-abdominal instrumentation. Consequently, it significantly reduces postoperative pain and eliminates the need for incision care. Notably, although the EBD group experienced a faster recovery, there was a non-significant difference in the “time to first meal” between the two groups (P = 0.305), likely because both procedures had minimal impact on gastrointestinal function.

The overall complication rate in the CED group was 25.81%, significantly higher than the 3.57% observed in the EBD group (P = 0.044). Complications in the CED group were primarily due to drain-related issues, including dislodgement (9.68%) and obstruction (3.23%), followed by incision infections (6.45%) and abdominal adhesions (3.23%). These complications are closely associated with the invasive nature of CED surgery, which requires the placement of an external drain (T-tube or catheter) in the gallbladder or cyst. Children with thinner abdominal walls and greater mobility are more susceptible to drain displacement due to positional changes or external pulling (7). Additionally, the abdominal wall incision from open or laparoscopic surgery compromises skin barrier function, while intraoperative electrocoagulation or suture techniques may cause local ischemia and necrosis, creating an environment conducive to bacterial colonization (24). In the CED group, one child developed postoperative intestinal adhesions, and intraoperative findings revealed extensive fibrosis of the hepatic-duodenal ligament, consistent with the “secondary surgery adhesion risk model,” which suggests that more traumatic initial surgeries increase the likelihood of adhesions in subsequent radical procedures (25).

In contrast, EBD offers greater stability by utilizing the endoscopic placement of a nasobiliary tube or stent, eliminating the need for an abdominal wall incision. The drain is secured through the nasal cavity or intestine, reducing the risk of dislodgement or obstruction. In this study, no drain dislodgement or obstruction occurred in the EBD group, and only one case of transient hyperamylasemia was observed, potentially related to the temporary elevation of pancreatic duct pressure during ERCP (26). This finding aligns with the report by Tsuchiya et al., which noted only one case of mild pancreatitis after EBD in 15 children with CC (8), indicating that the safety of ERCP in children can be further improved through technical advancements.

Compared to the CED group, the interval to definitive surgery was shorter in the EBD group (median: 14 days vs. 21 days, P = 0.002), with a lower rate of intermediate conversion to open surgery (3.57% vs. 29.03%, P = 0.024), and lower levels of TB (8.40 vs. 16.20 μmol/L, P = 0.019) and transaminases (ALT: 36 vs. 49 U/L; AST: 37 vs. 49 U/L, P < 0.01). These findings suggest that EBD can enhance preoperative preparation for radical resection and improve the success rate of minimally invasive procedures. The shortened interval reflects the superior efficacy of EBD in relieving cholestasis and systemic inflammation while reducing pericatheteric edema and fibrosis—key factors for the safe resection of cysts. Although CED provides direct bile drainage for immediate symptomatic relief and inflammation control, its invasive nature may exacerbate systemic inflammatory responses and delay hepatic function recovery (27). Similarly, Sun et al. (16) demonstrated that effective biliary decompression through endoscopic stenting can shorten the inflammatory “cooling” period, allowing for earlier definitive intervention. In contrast, Ten Broek et al. noted that the significantly higher conversion rates to open surgery in the CED group may be attributed to CED-induced peritoneal adhesions and fibrosis, which distort hepatobiliary anatomy and complicate subsequent minimally invasive resections. The rapid biochemical improvement with EBD is consistent with Tsuchiya et al. (8), who suggest that accelerated recovery is due to reduced medical trauma and preservation of biliary anatomy. However, technical limitations (mismatched instrumentation for younger patients’ biliary tracts) may temporarily hinder the broader application of EBD (17). Overall, these findings support using EBD as a physiologically favorable transitional strategy to expedite radical surgery, reduce perioperative risks, and improve the success rate of minimally invasive procedures.

The EBD, through internal stents or nasobiliary drainage, not only ensures effective bile drainage but also preserves the continuity of the biliary physiological channels. Additionally, intraoperative cholangiography during EBD provides a clear visualization of the pancreaticobiliary duct and allows for detecting abnormalities in pancreaticobiliary flow (32 cases of PBM were identified in this study). Compared to magnetic resonance cholangiopancreatography, ERCP offers the advantage of identifying abnormalities in small bile ducts and paracolic hepatic ducts, which is crucial for planning subsequent radical surgeries, such as choledochal cyst resection and hepatic duct jejunostomy (13). In this research, the interval between second-stage radical surgeries was significantly shorter in the EBD group than in the CED group, further highlighting the role of EBD in controlling inflammation and optimizing surgical timing.

This study has several limitations: (1) Despite using strict inclusion and exclusion criteria, retrospective studies inherently face challenges in controlling for confounding factors (variations in the surgical team experience and nutritional status of the children). For instance, the EBD group was treated by three surgeons with specialized endoscopic training, whereas the CED group may have had different surgeons, potentially influencing the outcomes. (2) The relatively small sample size of 59 cases and the lack of long-term follow-up data (incidence of cholangiocarcinoma, risk of anastomotic stenosis) limit the ability to assess the long-term impact of EBD. Future prospective multicenter randomized controlled trials with larger sample sizes and extended follow-up are needed to verify the efficacy and safety of EBD. Moreover, this study was conducted in Wuhan Children’s Hospital (a specialized pediatric ERCP center in China), whereas most primary hospitals still rely on CED techniques. Establishing a standardized training system for EBD is, therefore, essential. This study used adult-standard equipment and accessories, highlighting the need to develop finer-diameter biliary stents and pediatric-specific endoscopic tools to accommodate better the unique anatomical characteristics of children's digestive and biliary tracts.

EBD has indicated significant advantages in treating CC complicated by severe cholangitis in children. Its minimally invasive nature, safety, efficiency, and low complication rate make it a highly favorable alternative to traditional external drainage. Moving forward, the standardization and broader adoption of ERCP in pediatric care should be protected through technological advancements and multidisciplinary collaboration to improve clinical outcomes for this condition further.