Complete stone removal by using traditional, less invasive methods such as endoscopic Retrograde Cholangiopancreatography(ERCP), endoscopic papillary balloon dilation (EPBD), and percutaneous transhepatic balloon dilation (PTPBD) were challenging in refractory choledocholithiasis, especially when CBDS bigger than 15mm was impacted. The authors showed their experiences of the advantages of combination of FREDDY and PTPBD to manage these complicated cases and verified its efficacy and safety in the present study.
European Society of Gastrointestinal Endoscopy (ESGE) recommended stone extraction for all patients with CBDS, symptomatic or not, who were fit enough to tolerate the intervention13. Multiple studies showed that larger stones were inversely correlated with successful biliary clearance during ERCP14. Biliary sphincterotomy with a balloon dilation time of 30 s could significantly increase stone extraction and reduce the frequency of post-ERCP pancreatitis15,16. Mechanical bile stone lithotripsy on difficult bile duct stones could produce around 90% successful rate with minimal complications.17,18 But a randomized study showed that Mechanical lithotripsy had a significantly lower stone clearance rate in the first session compared with laser lithotripsy (63% vs. 100%; P < 0.01)19. Extra-corporeal shock wave lithotripsy (ESWL) also could be an alternative in difficult common bile duct stones (DCBDS), with a success rate greater than 90%, and a recurrence rate of 20% over a median follow-up of 4 years20. stenting for immediate and definitive stone treatment21, papillary large balloon dilation22
In 1986, Hochberger et al. reported performing the first successful endoscopic retrograde laser lithotripsy in humans using a flash lamp-pulsed millisecond meodymium:YAG laser.23 With the development of microsecond-pulsed dye laser systems that allowed the formation of plasma-induced shock waves, laser lithotripsy has become a commonly accepted modality for the treatment of difficult CBDS.
Most studies on laser lithotripsy for CBDS removal involved endoscopic guidance, but sometimes it might be difficult to perform this procedure. Himanshu Verma et al. reported a case of a 91-year-old woman with a medical history of gallstone ileus and prior ERCP who experienced several failed treatments,10 such as ERCP with spyglass cholangioscopy, Holmium laser lithotripsy, and cholangioscopy with percutaneous transhepatic cholangiography access to help position the stone for laser lithotripsy, for removing large CBDS; finally, the stone was successfully removed through percutaneous transhepatic cholangiography combined with flexible ureteroscope-guided laser lithotripsy.
The present study presented experience of percutaneous transhepatic flexible ureteroscope-guided FREDDY laser lithotripsy for refractory choledocholithiasis with a technical successful rate of 100%, low incidence of haemobilia which need correction, and absence of other Grade C or severer procedure-related adverse effects, such as perioperative death or intestinal and bile duct perforation.
The percutaneous access to the biliary tree was established by a 12-F 35-cm-long sheath, which was specifically suitable for the flexible ureteroscope to get through. One laser-related instrument complication was ureteroscope damage, which occurred during the initial application of the technique. Accurate positioning, complete view of the working area, and close coordination of ureteroscope and laser were useful to avoid this.
The selected pulse energy usually was 120 mJ, and the pulse frequency was 5 Hz. Higher energy and frequencies could crush the stones more efficiently, but these could shorten the service life. The usual selection was enough, except for stiff cholelithiasis. In addition to impact stones,24 the composition of choledocholithiasis was another influencing factor of lithotripsy. In this study, the ratio of bilirubin stones was significantly higher than usual,25 which usually require more lithotripsy frequency or higher energy and pulse frequency because of its rigidity.
For refractory choledocholithiasis, in the present study, none pancreatitis occurred. The main reason for this might be the smaller size of stones after lithotripsy, and a small-sized balloon might be capable of pushing the stones into the duodenum.
Although several studies have shown that endoscopic sphincterotomy plus balloon dilation was safe and effective for large CBDS removal, owing to the improvements of laser technology, more and more endoscopists preferred lithotripsy plus balloon dilation.26-28 Peroral cholangioscopy-guided lithotripsy achieved a technical success rate of 80%-86% in a single procedure, and was significantly more likely indicated for stones ≤30 mm in size than for stones with >30 mm in size.29,30 In the present study, no CBDS had a size of ˃30 mm, and the technical success rate was 100%. However, there were no cases of recurrence at 1 year, indicating that the PTFU-FREDDY was better than the simple PTPBD procedure we reported before,31 and ERCP alone,5 similar to choledochoscopy-guided laser lithotripsy,32 but with less complications. Digital single-operator cholangioscopy with electrohydraulic and laser lithotripsy is also effective in removing difficult biliary stones,33 but the procedural injury is larger than that of PTFU-FREDDY. A 10-year retrospective study showed that multiple CBDS (≥2), cholesterol stone, and sharp bile duct angulation (<145°) are associated with recurrent CBDS after cholecystectomy.34 To prevent recurrence, ursodesoxycholic acid was administered in this study,6 and a prospective cholelithiasis-related bile acid metabolomics have been initiated in multiple centers.
Large difficult CBDS also can be managed either by open surgery or laparoscopically with comparable and acceptable outcomes and without the need for multiple ERCP sessions due to their related morbidities.35 Open choledocoscopy was considered to be more suitable for stone clearance than a T-tube.36
For concurrent gallbladder and CBD stones, Liu et al. introduced a novel technique, which they referred to as sequential percutaneous transhepatic balloon dilation (PTBD) and percutaneous transhepatic extraction and balloon dilation (PTEBD).37 In the present study, patients were treated with routine PTFU-FREDDY, followed by percutaneous transcyst access PTFU-FREDDY.
Recently, a retrospective analysis study reported the outcomes of percutaneous transhepatic biliary laser lithotripsy for intrahepatic cholelithiasis,38 which achieved a 100% success rate in fragmenting the target stones. Eleven (92%) out of the 12 patients had successful first pass extraction of target stone fragments, and two patients (2/12; 17%) required repeat lithotripsy. In this study, the authors exclude the CBDS with concurrent multiple intrahepatic cholelithiasis, considering that it was difficult to ensure complete intrahepatic calculi fragmentation and discharge. In the following research, these patients would be prioritized for admission and treatment, and a special report would be presented.
The limitation of this study includes its small sample size and retrospective nature. More prospective, multicenter, randomised controlled trials are necessary to confirm the results of this study.
In conclusion, PTFU-FREDDY is a safe and efficient alternative treatment for refractory choledocholithiasis, especially when traditional treatments are difficult to perform or failed.