Clinical Case Summary

We report the case of a 16-year-old boy followed since age 10 for pancolitis-type ulcerative colitis (UC), resistant to 5-ASA, corticosteroids, immunosuppressants, anti-TNFα, and recently deemed refractory to ustekinumab. The disease was complicated by primary sclerosing cholangitis (PSC), leading to decompensated cirrhosis.
The patient presented with a moderate flare during ustekinumab induction, including diarrhea, rectal syndrome, abdominal pain, intractable vomiting, inflammatory lower-back pain, and new-onset ascites.
Colonoscopy revealed multiple polyps from rectum to cecum, some with irregular, raspberry-like surfaces, arising on normal-appearing mucosa without erythema or ulceration. Upper endoscopy, performed due to vomiting and hematemesis, showed grade III esophageal varices, portal hypertensive gastropathy, and multiple gastric polyps, some with similar irregular surfaces. MR enterography, though limited by suboptimal bowel distension, showed no small bowel polyposis.
These unexpected endoscopic findings introduced new challenges. Management options included treatment of refractory UC, assessment and surveillance of colonic and gastric polyps—raising concern for an underlying polyposis syndrome—and liver transplant evaluation for cirrhosis. The patient was treated with IV corticosteroids, then transitioned to an oral taper after clinical improvement.
Due to the complexity, a combined therapeutic approach (colectomy, gastrectomy, and liver transplantation) was considered unfeasible. The patient and family were counseled and referred to a national transplant and surgical center for sequential management planning: liver transplantation, followed by colectomy and endoscopic resection of gastric polyps.
This rare case highlights the therapeutic and diagnostic complexity of managing refractory pediatric UC with PSC, cirrhosis, and gastrointestinal polyposis, necessitating a highly individualized, multidisciplinary approach.

References

Figure 1 showing endoscopic images of the gastric (1a) and colonic (1b) polyposis
Figure 2 showing histological findings of biopsies of some of the gastric (2a) and colonic (2b) polyps
Figure 3 MR enterography of the patient showing no signs of small bowel involvement

Introduction

Endoscopic retrograde cholangiopancreatography (ERCP) is recognized as a foundational procedure within the realm of interventional gastroenterology. Nevertheless, a significant amount of hands-on experience is required to achieve proficiency in this procedure, particularly with regard to the performance of sophisticated therapeutic maneuvers. Access to authentic training cases remains limited, while the use of cadaveric or live animal models presents distinct ethical, logistical and financial challenges (1). The advent of 3D printing technology paved the way for the development of advanced medical simulators. This study utilized computer-aided design and fused deposition modeling techniques to engineer an ERCP simulator that is both anatomically accurate and enables the training of trainee physicians in the intricate procedures of their chosen discipline (2). The simulator's modular design allows it to replicate a spectrum of papillary conditions, enabling targeted training in anatomies that are resistant to cannulation, as well as high-risk procedures like precut sphincterotomy and fistulotomy.

Aims & Methods

The design process for the ERCP simulator employed accessible parametric modeling software. Fabrication of the primary structural components, including the pancreas, the duodenum, and the bile ducts, were undertaken using polylactic acid (PLA) filament, a material that is both widely accessible and economical, thereby ensuring adequate rigidity and durability. The interchangeable papillary components were produced using flexible thermoplastic polyurethane (TPU) 95A filament, selected for its elasticity and capacity to be readily incised during procedures such as endoscopic sphincterotomy (EST). This allowed for easy exchangeability and facilitated the acquisition of skills by novice endoscopists. This process were selected on the basis of accessibility, user-friendly interface and cost-effectiveness, enabling replication in diverse settings. The biliary and pancreatic ductal lumens were meticulously calibrated to represent a range of procedural difficulty, with internal diameters that closely mirrored real anatomical variations.

Results

The simulator exhibited a high degree of anatomical and biomechanical fidelity, featuring a structurally stable duodenal framework and a flexible papillary interface. The simulator accurately reproduced tactile feedback experienced by gastroenterologists during ERCP, thereby validating its efficacy as a training tool. Furthermore, the simulator was enabled meticulous rehearsal of EST through sphincterotomy incisions and facilitated fistulotomy simulation using an elastomeric papilla structure. The simulator's design is both cost-effective and easily replicable, making it a valuable asset for continuing education and training in this field (3,4).

Conclusion

The ERCP simulator, fabricated using 3D printing technology, can be regarded as both technologically advanced and economically efficient for a number of complex procedures. These encompass endoscopic sphincterotomy, precut techniques, fistulotomy and stent placement. The simulator's design, featuring a modular papillary system, was crafted to provide a structured and progressive learning environment for novice users as well as experienced endoscopists. The simulator's cost-effectiveness, ease of scaling up and potential for wide dissemination signify a paradigm shift in ERCP education, facilitating proficiency acquisition in complex interventional endoscopy with greater efficiency and safety. Further investigations are needed for the simulator in ERCP training.

References

1. Lee S, Ahn JY, Han M, Lee GH, Na HK, Jung KW, et al. Efficacy of a three-dimensional-printed training simulator for endoscopic biopsy in the stomach. Gut and liver. 2017;12(2):149.
2. Zhang Y, Chen L, Hu B. Advances of 3D printing in gastroenterology and where it might be going. International Journal of Bioprinting. 2023;9(6):0149.
3. Lee DS, Ahn JY, Lee GH. A newly designed 3-dimensional printer-based gastric hemostasis simulator with two modules for endoscopic trainees (with video). Gut and Liver. 2019;13(4):415.
4. Bundy JJ, Weadock WJ, Chick JFB, Srinivasa RN, Patel N, Johnson E, et al. Three-dimensional printing facilitates creation of a biliary endoscopy phantom for interventional radiology-operated endoscopy training. Current Problems in Diagnostic Radiology. 2019;48(5):456-61.