The prevalence of cholelithiasis necessitating cholecystectomy in children is on the rise. However, the perioperative evaluation for CBD stones in pediatric patients undergoing cholecystectomy relies primarily on guidelines developed for adults. Previous studies have highlighted that the sensitivity of these adult guidelines is relatively low when applied to the pediatric population, emphasizing the need for pediatric-specific guidelines [10]. Although several scoring systems have been proposed to predict CBD stones in children [8, 18], there are currently no structured guidelines specifically tailored for risk stratification and management of pediatric patients undergoing cholecystectomy for cholelithiasis.

Our results show that common bile duct stones complicate cholelithiasis in 20% of pediatric patients, presenting as gallstone pancreatitis, cholangitis, or choledocholithiasis. This prevalence aligns with previous findings reported in the literature [23]. However, the rate of true CBD stones mandating CBD clearance is probably closer to 10%. As in previous studies involving both children and adults, elevated bilirubin, filling defects, and dilated CBD observed on ultrasound were highly associated with CBD stones. However, it is challenging to determine which risk factors can independently predict CBD stones and which are clinically significant only when accompanied by other factors, as all these indicators are highly interrelated and represent the same pathophysiological condition. Regarding filling defects on US, it is widely agreed that these defects mandate, in adults and in children, a perioperative attempt at CBD clearance. Our findings also support this approach. However, although filling defects carry a high positive predictive value, they are described as particularly insensitive and thus serve as a poor screening tool [18]. In this cohort, out of 16 children who were eventually diagnosed with CBD stones, less than half presented with a filling defect on primary imaging (7 children, 44%). Regarding CBD dilation, although it is highly associated with the presence of CBD stones, some previous literature casts doubt on its value as a solitary predictor when liver function tests (LFTs) and bilirubin are normal [21]. While for adults the CBD cutoff is more unequivocal, applying these adult cutoffs to children results in less than 50% detection of CBD stones. In children, there is variability in CBD diameter, and the true cutoff for pathologic CBD is not well established and likely varies with age [24]. Moreover, while adults presenting with solitary CBD dilatation typically require further assessment, ampullary tumors are extremely rare in children, and so these patients might not need any further evaluation when CBD stones are excluded [25].

In this study, we addressed elevated bilirubin levels, defined as total bilirubin > 4 mg/dL and direct bilirubin > 20%, among both hemolytic and non-hemolytic patients. While other studies have excluded hemolytic patients due to variations in liver function tests and bilirubin levels, we thought it important to maintain a structured approach that is also applicable to children with hemolytic disorders. Thus, we incorporated the standard cutoff for conjugated bilirubin into the ASGE criteria, ensuring that only children with true conjugated hyperbilirubinemia were classified as high risk. Notably, none of the children with asymptomatic hemolysis-related cholelithiasis met the defined bilirubin cutoff. This finding supports our conclusion, as it suggests that this cutoff effectively distinguishes between bilirubin elevation caused by hemolysis and bilirubin elevation resulting from complicated cholelithiasis. It is important to note that we did not examine any bilirubin cutoffs other than those specified in the ASGE guidelines. However, we believe that a larger cohort may be necessary to establish precise bilirubin cutoffs for children, which might require adjustment based on age or body measurements.

As no single reliable predictor for CBD stones exists, any protocol for biliary tree clearance should aim to balance sensitivity and specificity to minimize the risks of false-positive and false-negative cases. Overestimating the risk for CBD stones may lead to unnecessary preoperative ERCP, exposing patients to potential complications such as pancreatitis, bleeding, and anesthesia-related adverse events. Conversely, underestimating the risk may delay necessary intervention for CBD stones, potentially resulting in postoperative cholangitis, pancreatitis, or the need for urgent ERCP.

According to this cohort, the sensitivity, specificity, PPV, and NPV of the ASGE guidelines were recorded at 56.2, 91.9, 40.9 and 95.5%, respectively. Several validation studies demonstrated a similar sensitivity of 37–68% and a specificity of 52–80% for the presence of CBD stones in ASGE high-risk adults [26–29]. A study applying ASGE criteria to children undergoing ERCP demonstrated a relatively low sensitivity of 20% with a specificity of 91% for high-risk criteria. [10]. However, it is difficult to generalize these results to all children with cholelithiasis, as those who underwent ERCP represent a selected subgroup likely already having a high prevalence of high-risk predictors. When adding elevated bilirubin as a solitary predictor in our cohort, the sensitivity rose to 68.8%, with specificity of 87.6%. Based on this finding, we think it is reasonable to perform upfront preoperative ERCP for children with a consistent bilirubin elevation of > 4 mg/dl with > 20% conjugated without a confirmed CBD dilatation. Given that cutoffs for CBD diameter in children are less established than in adults, we believe it is unwise to mandate invasive evaluation of the biliary tree in CBD dilatation. Regarding children with hemolytic disorders, the ASGE guidelines demonstrated very good predictive value for this patient group. Notably, modifying the guidelines to include solitary bilirubin elevation as a high-risk feature reduced specificity without affecting sensitivity; however, both remained relatively high.

In our cohort, only three patients underwent IOC. This was primarily due to the cohort’s relatively older data range starting from 2011 and the higher availability of ERCP services at our institution. Nevertheless, we think it is necessary to address recent publications in pediatric patients suggesting that IOC with a laparoscopic common bile duct exploration (LCBDE) as necessary could replace most preoperative ERCP procedures. This approach has been shown to reduce hospitalization time and time to definitive intervention, while also resulting in fewer procedures [30–32]. It is hard to evaluate post hoc the probability of a successful ‘surgery-first’ approach in this cohort, specifically due to the lack of data regarding the size of stones extracted during ERCP. Nevertheless, based on previous data, we do believe it is reasonable to suggest IOC ± LCBDE for pediatric patients with high-risk features on preoperative evaluation in experienced institutions where this option is highly available.

Based on our findings and previously published data regarding the prevalence and risk factors for CBD stones in pediatric patients, we suggest this algorithm for the perioperative evaluation of CBD stones in pediatric patients prior to cholecystectomy (Fig. 1).

This study’s limitations revolve around its retrospective nature and single-center experience. The decision to continue further evaluation of the biliary tree was based on clinical judgment and resource availability; thus, not all patients underwent the same evaluation. Moreover, quantifying the true rate of CBD stones necessitating bile duct clearance is challenging, as biliary stones are probably a more dynamic condition: some of the stones evacuated during ERCP might prove to be clinically insignificant post-cholecystectomy. Additionally, some postoperative biliary stones might have migrated to the common bile duct during surgery and do not represent true preoperative CBD stones. However, we recognize that a positive preoperative ERCP is considered justified, and that the presence of postoperative evidence of choledocholithiasis may suggest a preoperative retained stone. Nevertheless, while other studies lack follow-up for patients who undergo cholecystectomy without any further workout, we retrospectively screened all files. This allowed us to accurately quantify the true rate of complications due to retained stones in these patients. Further prospective studies with larger cohorts are necessary to properly evaluate the algorithm for pediatric preoperative biliary clearance suggested in this paper.