Duodenoscopes and accessories

Duodenoscopes are the standard endoscopes used for pediatric ERCP. In our practice, the “adult” therapeutic duodenoscope can be used in most children above 10 kg in weight, reserving the smaller endoscopes for children under 10 kg or in some cases less than 12–18 months old. This is due more to necessity and lack of availability of size‐ and age‐appropriate duodenoscopes worldwide. A list of commercially available and secondary market endoscopes is given in Table 37.1. Some experts advocate the use of an 11 mm therapeutic duodenoscope in older children. Newer models with slightly larger working channel diameters relative to endoscope size may allow some modfications in these smaller and younger patients.

The smallest duodenoscope has an insertion tube diameter of 7.5 mm, with a 2.0 mm working channel. This endoscope is designed for neonates and infants who weigh less than 10 kg. The major limitation with this endoscope is the relative scarcity of functional tools for the 2 mm channel, triple‐lumen or otherwise, and the devices must be 5 Fr or smaller. Other difficulties with the smaller duodenoscopes include increased resistance when passing devices through the distal portion of the endoscope, inability of the elevator to fully angulate, limiting access to the major papilla, and inadequate suction. Risk of accidental thermal injury and perforation of the duodenal wall limit the utility of therapeutic procedures with electrosurgical devices. However, sphincterotomy with a 5 Fr device has been reported.

Unfortunately, many of the smaller caliber endoscopes have become relics. The market for duodenoscopes worldwide has been impacted by the carbapenem‐resistant Enterobacteriaceae (CRE) infections noted to affect the elevator of most duodenoscopes. For this reason, the market has been affected in two ways: (i) continual efforts to minimize infection during reprocessing with the introduction of new endoscopes, (ii) discontinuation of production and repairs by the primary manufacturer for the older endoscopes. The result has been a challenge for pediatric ERCP in that the smaller duodenoscopes are now difficult to find and repair, with the caveat that there may be risks in reprocessing. Ultimately, endoscope manufacturers will need to create smaller duodenoscopes with appropriate channel sizes to accommodate the needs of the patients without compromising the issues related to reprocessing and cleaning of the elevator.

Similar to the challenges of the endoscope itself are the tools which can be placed through the working channel. With the trend in therapeutic over diagnostic ERCP, catheters, wires, and other devices should be tailored to the case. The choice of a particular accessory is dictated by the indications, for example, choledocholithiasis or stricture management.

Endoscopic retrograde cholangiopancreatography is a combined endoscopic and radiological technique and requires an optimal set‐up of fluoroscopy equipment and the participation of a well‐trained radiologist or radiology technician. A percutaneous transhepatic cholangiography (PTC) to establish bile drainage in case of a failed ERCP can be performed by interventional radiologists. Additionally, a PTC and ERCP rendezvous technique is an effective way to treat patients with biliary obstruction. Different types of contrasts media are available. The contrast can be diluted in saline, most commonly in stone disease.

In the 1970s Kawai pioneered the intraductal endoscope for direct visualization of the biliary and pancreatic tree. The initial intraductal endoscopes required a “mother–daughter” system with two endoscopists. Since that time, single‐operator fiberoptic and digital endoscopes have become available for use in children and adults. This has been reported in children (as young as 18 months old) for diagnostic and therapeutic indications including stone disease, postsurgical complications, and tumor evaluation. Intraductal endoscopes can also be used percutaneously in conjunction with interventional radiology, via percutaneous catheter.

Performing ERCP in children

Endoscopic retrograde cholangiopancreatography is a combined endoscopic and radiologic technique and requires an optimal set‐up of fluoroscopy equipment, endoscopy tower, electrocautery, and other tools. Using a duodenoscope, the procedure is routinely performed with the patient in the prone position, although it can be performed supine. Esophageal intubation with the side‐viewing endoscope is different compared to front‐viewing instruments. Although it is almost a blind intubation maneuver without direct visualization, it should be done to avoid trauma of the cervical esophagus or perforation of the piriform sinus.

The duodenoscope is inserted into the mouth along the middle of the tongue (with the light source and elevator facing the commissure of the right lip). The endoscope is torqued counterclockwise, with gradual deflection of the distal end of the endoscope towards the posterior wall of the pharynx and advancement into the esophagus. A slight increase in pressure is noted along the cricopharyngeus, with decreased resistance at the moment of esophageal intubation, with the appearance of gliding esophageal mucosa with a clear vascular pattern. Attempts to view the esophageal lumen are counterproductive and may lead to mucosal laceration. The endoscope is advanced without resistance until the vascular pattern disappears. It is usually associated with entrance into the stomach and close contact of the lens with gastric mucosa at the level of the upper gastric body.

For proper orientation, the endoscope should be pulled back and rotated counterclockwise with simultaneous deflection of the distal end to the left. Once the panoramic view of the gastric body is established, the duodenoscope is advanced forward and rotated clockwise. Care should be taken to avoid slipping back into the gastric body. During the transition between the gastric body and the antrum, the lumen of the stomach may disappear. Appearance of the sliding gastric mucosa is reassuring unless significant resistance occurs. The view of the gastric lumen is reestablished by elevating the tip of the duodenoscope and/or pulling the endoscope back gently. In patients with a J‐shaped stomach or if there is difficulty in identifying the antrum, the right shoulder of the patient can be rotated towards the midline. Longitudinal prepyloric folds are a good orientation to follow. Transition through the pylorus is accomplished by significant reduction of resistance and changes of mucosal pattern from smooth to the velvety appearance of the villi.

The second portion of the duodenum is reached by upward deflection of the distal tip, clockwise rotation and advancement of the scope. The is the “long” position with the majority of the shaft forming a loop along the gastric wall. To convert it to the “short” position, which is more desirable for cannulation of the major ampulla, the tip of the endoscope should be rotated clockwise and pulled back simultaneously. In infants, it can be difficult to navigate the instrument into the “short” position, often due to the relatively shallow distance from the second portion of the duodenum back to the pylorus. This occasionally leaves no alternative but the “long” position despite the limitations: excessive stretching of the stomach and duodenum, masking of the common bile duct by overlapping duodenoscope (obscuring the image), difficulties with control of the distal tip of the scope, and positioning of the cannula or therapeutic accessories.

As ERCP requires fluoroscopic guidance, it is important to remember that children are at increased risk for exposure to ionizing radiation. We recommend formal or informal fluoroscopy training, as well as additional attempts to limit radiation exposure using pulse fluoroscopy. The ESGE/ESPGHAN also recommends the protection of radiosensitive organs with adjustment of collimation to the smaller size of children. Documentation of fluoroscopic dosage and exposure times should be performed as a quality indicator.

Endoscopic retrograde cholangiopancreatography in children should be performed by an experienced endoscopist in a high‐volume center with pediatric involvement. The ASGE suggests a minimum of 200 diagnostic and therapeutic ERCPs prior to assessing competence and NASPGHAN recommends the same number of ERCPs in pediatrics. Data in adults suggest increased adverse events in those performing fewer than 50 endoscopic sphincterotomies per year, highlighting the importance of ongoing assessment. ERCP typically requires general anesthesia (GA), and ESGE/ESPGHAN recommends GA for teenagers, although deep sedation can be considered in older children.

Adverse events in pediatric ERCP

The overall rate of adverse events associated with pediatric ERCP is around 5–8%, compared to the 1–13% reported in adults. Beyond standard endoscopy, each of the technical components during ERCP can be related to an adverse event.

The most commonly reported adverse event is pancreatitis. Based on both adult and pediatric literature, post‐ERCP pancreatitis (PEP) is more likely to occur with repeated attempts at wire cannulation, pancreatic sphincterotomy, opacification of secondary and tertiary branches (parenchimography), and acute pancreatitis. Rates of PEP as low as 2.5% have been reported, but typically rates of ~10% are not uncommon and are similar when performed by an adult or pediatric ERCPist. PEP can be mitigated by precise and selective cannulation of the major papilla, and limited injections of the pancreatic duct. NSAIDs (rectal indomethacin) and pancreatic stenting have been shown to decrease rates of PEP in adults. The ESGE/ESPHGAN strongly recommend NSAID prophylaxis in pediatric ERCP >14 years of age. However, there is no consensus regarding these modalities in pediatric ERCP, although they are commonly used. Of note, there is a report in which PEP rates were increased after pancreatic stenting in children. Additionally, the role of octreotide (Sandostatin®) or serine protease inhibitors is unclear. Finally, there is a movement toward increased hydration protocols both before and after ERCP which may be important.

Several adverse events are specifically related to endoscopic biliary or pancreatic sphincterotomy (ES). Bleeding after ES is uncommon and typically can be controlled with injection or spray of 1:10 000 epinephrine. A needle that can be manipulated by the duodenoscope elevator is necessary. Balloon tamponade with an extraction balloon for 3–5 minutes can be used. Additional tools include hemostatic clips and stents (plastic and fully covered expandable metal), although angiography and surgical therapies could be used if endoscopic treatment was not successful or with persistent or more rapid bleeding.

Also related to sphincterotomy is the risk of retroperitoneal perforation of the duodenum which has been described in children.

Finally, infection, including cholangitis, is a well‐known risk of ERCP. The highest risk for infection is in patients with biliary obstruction from tumor, sclerosing cholangitis and liver transplant‐related stricture. Prophylactic antibiotics are recommended in these cases as well as patients with biliary obstruction unlikely to be resolved with adequate drainage. Systemic infections have been linked to CRE related to endoscope reprocessing and issues with the duodenoscope elevator. The US Centers for Disease Control and Prevention reported concerns to the FDA in 2013. Although CRE infections have been reported in pediatric patients, to date there have not been any reported cases in children linked to ERCP.

Biliary indications for diagnostic and therapeutic ERCP

Technical success (>90%) for ERCP in children is high. Results and complication rates (2.3–9.7%) of ERCP in children are similar to those in adults, with no procedure‐related mortality.

Biliary indications for diagnostic and therapeutic ERCP are listed in Table 37.2.

Choledochal cysts

Choledochal cysts (CC) are anomalies of bile ducts frequently associated with anomalous pancreaticobiliary union (ABPU); the so‐called “long common channel” is defined as a confluence of the common bile and pancreatic ducts external to the ampulla and duodenal wall (Figures 37.1 and 37.2). The association is reported in more than 80% of cases. CC are usually identified in infancy or childhood, although cases of delayed diagnosis in older children and adults have been reported. The Todani classification is the standard nomenclature for CC (Table 37.4). The common presentation includes abdominal pain, jaundice, and acute recurrent pancreatitis. Associated complications include intraductal stones, cholelithiasis, intrahepatic abscess, and biliary neoplasia.

The two most common surgical therapies for CC are complete cyst excision with either hepaticojejunostomy with a Roux‐en‐Y or duodenoduodenostomy. The diagnostic role of ERCP is to define the anatomy of the pancreaticobiliary junction. This information helps the surgeon estimate the distal level of the CC resection, avoiding complications due to preservation of a long remnant of a choledochal cyst.

In many children with CC complicated by intraductal lithiasis (biliary and/or pancreatic), ERCP with sphincterotomy serves as a bridge before definitive surgical therapy and decompression of the hepatobiliary system. Biliary stents are commonly used, however in ABPU can potentially obstruct the pancreatic duct depending on the angle of the junction.

In cases of small intramural choledochocele, an endoscopic unroofing of the cyst has been described, but there are no reports regarding the long‐term outcomes of children managed by this method. On rare occasions, biliary rhabdomyosarcoma can mimic clinical and radiographic findings of CC. ERCP with intraductal endoscopy has also been used for diagnostic purposes and directed biopsies. Endoscopic biopsy can reduce the need for diagnostic laparotomy and tumor spread related to percutaneous biopsy (Figures 37.3 and 37.4).

Type	Description	Occurence
1	1A: Segmental or diffuse saccular dilation of extrahepatic biliary tree 1B: Segmental dilation of CBD (more often in the distal portion), with normal bile duct between the cyst and cystic duct 1C: Fusiform dilation of CBD	80–90%
2	Choledochal diverticulum: isolated protrusion of the common bile duct wall	2%
3	Choledochocele: isolated involvement of the intraduodenal portion of CBD. The major duodenal papilla is bulging	1.5–5%
4	4a: Multiple dilations of intra‐ and extrahepatic bile ducts 4b: Multiple dilation of extrahepatic bile ducts	20%
5	Caroli disease: Multiple usually small dilations of the intrahepatic bile ducts

CBD, common bile duct.

Choledocholithiasis

Cholelithiasis has become more frequently diagnosed in children. Choledocholithiasis is reported in up to one‐third of symptomatic patients. As in adults, obesity and Hispanic background are increasingly recognized as important risk factors for gallstones in children. Sickle cell disease and other hemoglobinopathies remain important pediatric risk factors. Issa et al. reported 37% of 125 children who underwent ERCP for obstructive jaundice or biliary colic. All cases were managed endoscopically with ES and balloon stone extraction without the need for surgical CBD exploration.

Therapeutic ERCP with ES and stone extraction is the treatment of choice for children with choledocholithiasis post cholecystectomy. For children with cholelithiasis, there is no consensus on whether suspicion of common bile duct (CBD) stones warrants ERCP before laparoscopic cholecystectomy or routine intraoperative cholangiogram to eliminate the need for pre‐ or postoperative ERCP. However, there are growing data in children and adults that in patients with choledocholithiasis, cholecystectomy is ideally performed during the same hospital admission.

One of the challenges in the management of choledocholithiasis is identifying patients with the highest likelihood of having a stone at the time of endoscopy. The ASGE has previously suggested considering ERCP for patients with (i) stone visualized on imaging, (ii) total bilirubin greater than 4 mg/dL, or (iii) cholangitis. Additional considerations for ERCP are moderate likelihood of stones in patients with a total bilirubin of 1.8 mg/dL and a dilated bile duct above 6 mm. These criteria were unable to predict choledocholithiasis in a small series of pediatric patients, and conjugated bilirubin alone was best at predicting the risk of stone. This has been further evaluated in the multicenter international Pediatric ERCP Database Initiative (PEDI) demonstrating conjugated bilirubin as an important indicator. Of note, more than 35% of patients had a normal bilirubin, highlighting the challenges in these cases. Additionally, more than 50% of patients with gallstone pancreatitis passed their stone prior to ERCP, suggesting the complementary role of MRCP and endoscopic ultrasound (EUS).

In our practice, we perform ERCP prior to cholecystectomy in children with cholelithiasis, visualized stone or dilated CBD on abdominal ultrasound or cross‐sectional imaging, gallstone pancreatitis and elevated biochemical markers of obstruction (conjugated bilirubin and gamma‐glutamyl transferase). We also perform ERCP postoperatively in patients with persistently elevated or rising aminotransferases or related labs, abdominal pain and imaging suggestive of retained CBD stones.

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic progressive liver disorder, commonly associated with inflammatory bowel disease, characterized by ongoing inflammation, obliteration and fibrosis of both intra‐ and extrahepatic bile ducts. Approximately 50% of symptomatic patients will develop cirrhosis and liver failure and require liver transplantation. PSC is characterized by the development of multiple strictures dividing bile ducts into short segments of normal size or dilated bile ducts of a beaded or pearl necklace pattern (Figure 37.5). The gallbladder and cystic duct are involved in up to 15% of cases. PSC carries an increased risk of malignancy, especially cholangiocarcinoma.

Endoscopic retrograde cholangiopancreatography is indicated in children with suspected PSC, if the results of the MRCP are inconclusive. In some patients, cholestasis is secondary to a dominant stricture defined as a discrete area of narrowing with the extrahepatic biliary tree. Dominant strictures of the extrahepatic bile duct occur in 7–20% of patients with PSC and cholestasis. Patients with CBD stricture are candidates for therapeutic ERCP with the controversy surrounding the use of plastic stents compared to serial balloon dilations without stents. Stenting is associated with more infectious complications and adverse events compared to balloon dilations. A recent randomized controlled trial favors the use of balloon dilation alone, but the ESGE recommendations on PSC leave this decision to the endoscopist as to which method is used. ERCP treatment of dominant strictures can lower morbidity rates in adults compared with percutaneous techniques. Although there is consensus amongst adults, data are lacking on the timing of brushings and biopsies to evaluate for cholangiocarcinoma in pediatric patients. Intraductal endoscopy offers another method with which to investigate indeterminate stricture in these patients.

Postsurgical and posttraumatic biliary disease

A bile leak after laparoscopic cholecystectomy, liver transplantation or traumatic injuries of bile ducts can be successfully treated by ERCP with ES and biliary stent placement or nasobiliary drainage (Figure 37.6). A stricture of the CBD after cholecystectomy can be treated with plastic stents.

The clinical manifestations of a bile leak after blunt abdominal trauma are often insidious and nonspecific. It may delay diagnosis by a few days despite utilization of radioisotope scintigraphy in high‐risk injuries such as a laceration greater than 4–cm or extending into the porta hepatis. Early diagnosis reduces morbidity and hospitalization. ERCP with stent placement contributes to prompt discovery of bile leak sources and dramatic recovery by effective reduction of the pressure in the bile ducts even if a stent does not bridge the gap between the damaged ducts.

In patients with suspected strictures post liver transplant, ES with biliary stenting has been used within days of transplant (Figures ). We prefer plastic stents to FCMS, although they have been used in pediatric liver transplant recipients. Cast syndrome in which sludge and debris form a cast along the length of the duct may require intraductal endoscopy to evaluate and treat.

Functional biliary sphincter disorder (previously sphincter of Oddi dysfunction; SOD)

Functional biliary sphincter disorder (FBSD), previously referred to as SOD, is a rare cause of abdominal pain in children. It is considered as a motility disorder related to abnormal contractility of the sphincter without anatomical obstruction. The Rome IV Criteria are met for FBSD if a patient has all three: biliary type pain, elevated aminotransferases or dilated bile duct and the absence of bile duct stones or other structural abnormalities. Supportive criteria for FBSD include a normal amylase or lipase, abnormal sphincter of Oddi manometry or findings on hepatobiliary scintigraphy.

The former SOD type I is now thought to be a distinct entity caused by stenosis of the papilla, typically with associated abnormalities including elevated aminotransferases and/or pancreatic enzymes and ductal dilation. The treatment of papillary stenosis is typically biliary sphincterotomy. However, contributing to the change not only in name but also in management of SOD type II and III was a recent randomized double‐blinded study, EPISOD (Evaluating Predictors and Interventions in Sphincter of Oddi Dysfunction), which evaluated the role of sphincterotomy in SOD. Based on this trial, patients with SOD type III did not respond to sphincterotomy compared to sham treatment. Additionally, manometry findings did not correlate with patient outcomes. Although not the specific aim of the EPISOD trial, patients with SOD type II, with either lab or imaging abnormality, did not have the expected success of sphincterotomy. We do not recommend manometry or sphincterotomy for pediatric patients with FBSD (the former SOD type III). The role of sphincterotomy for pediatric patients with the former SOD II (abnormal imaging or blood tests) requires further study, but is likely to be treated as FBSD. If sphincterotomy is considered in these patients, a more extensive discussion about available evidence in adults may be appropriate. Of note, only limited data are available related to the sphincter pressure in children, in which 65 out of 245 children met criteria for elevated pressure.

Pancreatic pseudocyst, necrosis, and trauma

Acute fluid collections of the pancreas can develop into pancreatic pseudocysts. If there is pancreatic necrosis, these can become walled‐off necrosis (WON). Pancreatic pseudocyst and WON could be suspected based on clinical grounds: persistent abdominal pain, elevated amylase or lipase, or cholestasis due to distal CBD compression four weeks after an initial attack of acute pancreatitis or trauma. Transabdominal ultrasound may identify the collections, but MRCP and CT are the optimal diagnostic tests. Pseudocysts frequently resolve spontaneously.

Common indications for intervention are trauma‐related acute pancreatitis with increased risk of main duct disruption, presence of large, well‐organized pseudocysts six weeks after the episode of acute pancreatitis, and infected cysts. The endoscopic approach for children with pancreatic fluid collections has evolved, with transgastric drainage by EUS often the primary treatment. ERCP may be necessary but a large cyst may lead to distortion of the duct and also lead to inadequate treatment. In patients with traumatic pancreatitis, treatment includes ERCP with transductal placement with a pancreatic stent over the guidewire. Transgastric drainage (Figure 37.12) with either plastic stents or fully covered metal stents is typically done with EUS to avoid damage to neighboring vessels. The recurrence rate of fluid collections with older methods is approximately 15%. Surgery is indicated if the fluid collection of WON persists.

Conclusion

Endoscopic retrograde cholangiopancreatography is a very effective diagnostic and therapeutic procedure in children with pancreaticobiliary disorders. It is safe in the hands of an experienced pediatric gastroenterologist. Therapeutic ERCP can be used as a definitive treatment for children with specific pancreaticobiliary disorders and may serve as a bridge therapy to surgery.