In this retrospective study, CPAD occurred in 17% (11/65) of patients with DSP in the descending duodenum. In addition, female sex, tumor invasion to the MDP, and absence of biliary stents were identified as risk factors for CPAD.
Several studies have reported the development of CPAD [11, 17, 18]. SEMSs placed over the MDP can obstruct the flow of the bile and pancreatic ducts, resulting in CPAD. Thus, ideally, SEMS placement over the MDP should be avoided. However, this is often difficult for the following reasons. First, in cases with duodenal stenosis on the oral side of the MDP, the endoscope cannot approach the MDP, resulting in failure to confirm the location of the MDP. Second, in cases with duodenal stenosis on or near the MDP, SEMSs must be placed over the MDP for the treatment of mGOO symptoms, even though the MDP can be confirmed endoscopically. As SEMS placement over the MDP often cannot be avoided, endoscopists should be aware of the risk of CPAD when they place SEMSs in the descending duodenum. Therefore, knowledge regarding the incidence of and risk factors for CPAD is useful in clinical practice.
In this study, three main risk factors for CPAD were observed: female sex, tumor invasion to the MDP, and absence of biliary stents. The following points may explain our findings. First, female sex is a known risk factor for post-ERCP pancreatitis, although the reasons underlying this association remain unclear [22, 23]. Female patients may be more responsive to MDP-related irritation than male patients. Second, in patients with tumor invasion to the MDP, the biliary or pancreatic duct may exhibit a pre-obstructive state, and compression from the SEMS may easily trigger symptoms. This mechanism may be similar to that of acute cholecystitis after SEMS placement in the bile duct. Several previous studies have indicated that tumor involvement in the orifice of the cystic duct is a risk factor for cholecystitis after SEMS placement in the bile duct [24–26]. Third, biliary stents deployed across the MDP may create space between the MDP and duodenal stents, thus relieving MDP compression. Although our study revealed the three main risk factors associated with CPAD, the evidence that supports our results remains insufficient. Thus, further research will be required to validate our results.
According to our results, biliary stents prior to DSP may reduce the incidence of CPAD in patients with stenosis of the descending duodenum; however, previous studies have reported that DSP is a risk factor for the dysfunction of biliary stents deployed over the MDP; thus, transmural biliary drainage may be preferred over transpapillary biliary drainage for patients with mGOO accompanied by biliary obstruction [27, 28]. The common alternative treatment for DSP is surgical gastrojejunostomy, but patients with mGOO are often in poor general condition and unsuitable for surgical gastrojejunostomy. Recent studies have demonstrated the efficacy of endoscopic ultrasonography-guided gastroenterostomy (EUS-GE) in the management of mGOO . In one retrospective study, EUS-GE had a higher rate of initial clinical success and lower rate of stent failure requiring repeat intervention than DSP . In addition, in EUS-GE, there is no risk for cholangitis or pancreatitis because the SEMS is not placed over the MDP. Thus, EUS-GE may be suitable for patients with mGOO with a high risk of CPAD. However, EUS-GE poses many challenges, including the lack of dedicated devices and non-availability at many hospitals in Japan. Currently, DSP is the standard for mGOO treatment, even for patients at high risk of CPAD. Therefore, risk stratification for CPAD is required to inform patients in detail prior to DSP.
The present study had several limitations. First, there may have been unintentional bias because of its retrospective study design. Second, the sample size was too small given the single-center nature of the study, Third, although we assessed the risk for cholangitis and/or pancreatitis, the individual risk for cholangitis and pancreatitis could not be evaluated because of the small sample size. Thus, larger clinical trials are required to assess risk factors for cholangitis and pancreatitis separately.
In conclusion, our findings indicated that the incidence of acute cholangitis and/or pancreatitis was non-negligible among patients who underwent DSP in the descending duodenum. Female sex, absence of biliary stents, and tumor invasion to the MDP were identified as potential risk factors for CPAD. Risk stratification can allow endoscopists to better identify patients who are at significant risk and permit detailed informed consent and high-risk groups may be offered non-DSP treatment in the future.