In general, approximately 5–15% of bile duct stones failed to be detached with a single technique of sphincterotomy or EPBD, especially multiple and large CBDSs. Moreover, large common bile duct stone removal might need the concomitant use of EML, which is associated with severe procedure-related complications .
EPLBD uses a larger balloon size (12–20 mm) after limited EST is used as an alternative technique for removal of bile duct stones. This technique theoretically combines the advantages of balloon dilation and sphincterotomy by increasing stone extraction efficacy while minimizing the complications of them .
The present study revealed nonsignificant differences between the studied groups as regards the presence of periamullary diverticula (23% in EST/EPLBD group vs. 19% in EST group, P > 0.05). This excluded the role of periamullary diverticula in successful cannulation. These results agreed with Kim et al., 2010 , and Lee et al., 2011 , who demonstrated that the presence or absence of periampullary diverticula did not affect the ERCP procedure in limited EST+EPLBD and sole sphincterotomy groups.
The present study revealed that EPLBD with prior limited sphincterotomy significantly reduced the need for mechanical lithotripsy compared to sole sphincterotomy (4% vs 9%, P > 0.05). These results were in agreement with Guo et al., 2014 , and Tsuchida et al., 2015 , who reported that combining EPLBD with limited EST significantly decreased the need for EML as it achieved a spacious opening of the common bile duct. On the other hand, Heo et al., 2007 , demonstrated that combining EST with EPLBD didn`t significantly reduce the rate of mechanical lithotripsy compared to sole sphincterotomy. Moreover, Stefanidis et al., 2011  and Kim et al., 2016 , reported that mechanical lithotripsy is time consuming with high risk of complications and should be replaced by EPLBD in the era of removal of CBD stones.
The present study revealed that the procedure time was significantly shorter in EST/EPLBD group compared with EST group (37.530 ± 8.061 vs. 40.790 ± 10.741, p < 0.05), respectively. These results agreed with Itoi et al., 2009 , and Tsuchida et al., 2015 , who reported that EPLBD with limited EST significantly decreased the mean procedure time.
The technical success rate in the present study was achieved in all patients of both groups. However, the initial (first session) and overall success rates of complete stone removal were higher in the EST/EPLBD group compared to EST group, (84% vs. 70%, P > 0.05) and (94% vs. 90%, P > 0.05), respectively. These results were similar to the two studies done by Guo et al., 2014 , and Chu et al., 2017 , who reported insignificant difference between the limited EST+EPLBD and EST group as regards the initial and overall success rates of stone removal, although they were higher in the former group. In addition, Tsuchida et al., 2015 , reported a significant higher initial success rate and a significant lower mean number of sessions required for complete stone clearance in EST/EPLBD group (1.12) sessions vs. EST group (1.47), p = 0.002). Moreover, Liu et al., 2019  reported that EPLBD following limited or medium sphincterotomy can make it more effective in stone removal with reduction in the procedure time and the number of endoscopic sessions.
The present study revealed that the overall complications were 5% in the EST/EPLBD group compared to 11% in EST group (P = 0.118). These results agreed with previous reports but varied in their significance. Stefanidis et al., 2011 , reported significant lower overall adverse events in EST + EPLBD compared to SEST (4.4% vs. 20%, P = 0.049). In a systemic review of 30 studies done by Kim and Kim, 2013 , the overall complications were lower in sphincterotomy combined with EPLBD group than in sole sphincterotomy (8.3% vs 12.7%, OR = 1.60, P < 0.001).
The present work revealed that procedure-related pancreatitis in the EST group was 5% and 3% in EST/EPLBD group. These results agreed with a systematic review done by Junior et al., 2018 , who stated that post-endoscopic pancreatitis (PEP) tended to be less common in the EST/ELPBD group than in the EST group, although the difference was not statistically significant. Liao et al., 2012 , demonstrated that EPLBD with limited sphincterotomy significantly decreased the risk of PEP by adequate visualization and cannulation of the common bile duct. Furthermore, this technique prevents accidental pancreatic duct cannulation and avoids pressure overload on it.
Hwang et al., 2013 , founded that EPLBD with limited sphincterotomy reduced the need for mechanical lithotripsy. This prevented obstruction of the pancreatic duct orifice as a result of papillary edema or spasms induced by EML and therefore, minimizes the post-endoscopic pancreatitis. Moreover, Huang et al., 2018 , reported that endoscopic nasobiliary drainage catheters significantly lowered PEP. Therefore, Guo et al., 2015  and Park et al., 2018 , recommended routine postprocedure biliary drainage to minimize PEP. Furthermore, Park et al., 2018  stated that endoscopic experiences with peri-procedural patients’ optimization are essential in the prevention of PEP.
The present study revealed that six patients with PEP were younger than 60 years versus two patients aged more than 60 years. These results agreed with Weinberg et al., 2006 , who reported that PEP was higher in patients aged less than 60 years compared to those above 60 years, and the authors attributed that to the progressive decrease in pancreatic exocrine function with a lower risk of pancreatic injury with aging.
The present study revealed that procedure-related bleeding in the sole sphincterotomy group was 6% compared to 2% in EST/EPLBD group, (P = 0.306). There was a case of major bleeding in SEST group that required blood transfusion and hemostatic therapy, and seven cases had minor bleeding (2 in group I and 5 in group II) that was controlled by administration of hemostatic agents. Guo et al., 2014 , reported that the procedure-related bleeding was lower in EST/EPLBD group in comparsion to EST group [1/64 (1.6%) vs. 5/89 (5.6%), P < 0.05]. The lower risk of bleeding in EPLBD with prior limited EST group may be related to prevention of bleeding by effective compression done by the balloon and this technique may be recommended specially in patients with high risk of bleeding such as patients on anticoagulant therapy as well as patients with cirrhosis or end stage renal diseases .
None of the studied groups’ patients died or developed procedure-related perforation or cholangitis. These results agreed with Aujla et al., 2017 , who demonstrated that there was no reported cases of perforation, cholangitis, or mortality in either group. In contrast to the study done by Guo et al., 2014, who reported that there was two cases in sphincterotomy group died from multiple organ failure. Moreover, he reported that the lower risk of procedure-related duodenal perforation in EST/EPLBD group compared to sphincterotomy group could be related to the ability of the endoscopist to observe ampullary dilation status by side view endoscope and fluoroscopy. Moreover, this lower risk can be minimized by avoiding the size of the dilating balloon to exceed CBD diameter . Many previous studies showed that acute cholangitis developed more often in the sphincterotomy group in comparison to the EPLBD group, and this might be explained by the loss of sphincter function after sphincterotomy, which enables colonization of intestinal organisms into the biliary system .
In the current study, the failure of complete stone removal in EST/EPLBD and sole EST groups was (6% vs. 10%, respectively) and this was associated with larger transverse stone diameters (> 2 cm) and all those patients underwent surgical removal of CBDSs. These results agreed with previous reports. Aujla et al., 2017 , reported that large CBDSs > 17.4 mm was associated with significant failure of duct clearance. Kuo et al., 2016  and Chu et al., 2017  related failure of complete duct clearance to large stones (1.5–2 cm), present with large periamullary diverticulum and inadequate stone capture by the basket and they recommended open surgery in those patients.
Previous studies have indicated that biliary reflux in the early postoperative period is a major cause for long-term complications such as recurrence of CBDSs with sole sphincterotomy. By the combination of sphincterotomy and EPLBD, the occurrence of biliary reflux was minimized through limiting the damage of the papilla as well as the impairment of sphincter function, thus effectively preventing these complications in patients .
There were limitations in the current study. Our study only assessed short-term complications, not long-term complications, which could be important to evaluate the safety of the techniques. Also, a larger sample size or a non-inferiority trial might be necessary to confirm these results.