Efficacy of modified pancreatic duct stent drainage during endoscopic retrograde cholangiopancreatography for common bile duct stones

Abstract

BACKGROUND

Common bile duct stones pose a high risk of recurrence or disease progression if not promptly treated. However, there is still no optimal treatment approach.

AIM

To investigate the clinical efficacy of modified pancreatic duct stent drainage in endoscopic retrograde cholangiopancreatography (ERCP) for treating common bile duct stones.

METHODS

This retrospective study included 175 patients with common bile duct stones treated at Taizhou Fourth People’s Hospital between January 1, 2021, and November 30, 2023. The patients were divided into three groups-the modified pancreatic duct stent drainage group (59 cases), the nasobiliary drainage group (58 cases), and the standard biliary drainage group (58 cases). Preoperative general clinical data, laboratory indicators, and the visual analog scale (VAS) at two time points (24 hours before and after surgery) were compared, along with postoperative complications across the three groups.

RESULTS

Serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, total bilirubin, direct bilirubin, C-reactive protein, and amylase were significantly lower in the modified pancreatic duct stent drainage group and the standard biliary drainage group than those in the nasobiliary drainage group (P < 0.05). However, no statistically significant differences were observed in white blood cells, hemoglobin, or neutrophil levels among the three groups (P > 0.05). The standard biliary drainage group had significantly lower VAS scores [(4.36 ± 1.18) points] than those for the modified pancreatic duct stent drainage group [(4.92 ± 1.68) points] (P = 0.033), and the nasobiliary drainage group [(5.54 ± 1.24) points] (P = 0.017). There were no statistically significant differences in complication rates across the three groups (P > 0.05).

CONCLUSION

Compared to standard biliary drainage and nasobiliary drainage, the modified pancreatic duct stent used during ERCP for patients with bile duct stones significantly reduced hepatocyte injury, improved liver function parameters, alleviated inflammation and pain, enhanced patient comfort, and demonstrated superior safety.

Key Words: Modified pancreatic duct stent drainage; Endoscopic retrograde cholangiopancreatography; Common bile duct stones; Curative effect; Complications

Core Tip: There is currently a paucity of multidimensional comparative analyses concerning the clinical efficacy of modified pancreatic duct plastic stents for endoscopic retrograde biliary drainage, endoscopic nasobiliary drainage, and Christmas tree-shaped plastic stents for standard biliary drainage following endoscopic retrograde cholangiopancreatography (ERCP) for common bile duct stone removal. This study addresses this gap with a comprehensive analysis. Our findings reveal that compared to standard biliary drainage and nasobiliary drainage, modified pancreatic stents offer significant benefits, including a significant reduction in hepatocyte damage, improvement in liver function parameters, alleviated inflammation and pain, enhanced patient comfort, and increased treatment safety. Therefore, we recommend modified pancreatic plastic stents as the preferred post-ERCP drainage method for patients with common bile duct stones.

INTRODUCTION

Cholelithiasis of the common bile duct refers to the presence of stones at the distal end of the common bile duct. These stones are typically a mixture, with bile pigment stones being the most common type. The causes of choledocholithiasis in patients with choledochal cholelithiasis are multifaceted, resulting from factors such as cholangitis, roundworm infestations, and bile stasis. The etiology of the disease is complex, leading to a wide range of clinical manifestations, such as epigastric cramps, chills, and penetrating low back pain[1]. Choledochal stones occur in approximately 5%-20% of patients with cholelithiasis and in about 10% of those who undergo cholecystectomy[2,3]. Relevant epidemiological data showed that cholelithiasis is the most common biliary tract disease in the United States, with a mortality rate of 260.8 deaths per 100000 people. Each year, approximately 180000 patients receive treatment for cholelithiasis, while over 700000 undergo surgical procedures related to the condition[4]. Studies indicate that the incidence of common bile duct stones ranges from approximately 5% to 20%, with an increasing trend over time[5]. More than 20% of affected patients present with clinical symptoms such as fever, abdominal pain, and jaundice. In severe cases, complications, such as acute obstructive suppurative cholangitis and septic shock, may occur[6]. If left untreated, gallstones can lead to recurrent symptoms and disease progression, highlighting the critical need for timely and effective stone removal[7].

Currently, endoscopic retrograde cholangiopancreatography (ERCP) serves as a cornerstone in the clinical treatment of bile duct stones, effectively alleviating symptoms and facilitating their complete removal[8]. Image-guided techniques are essential in enhancing the precision and success of surgical interventions. Since its development in the 1960s, ERCP has evolved into a widely used procedure for managing common bile duct stones. It is an imaging technique involving the insertion of a catheter through a duodenoscope into the pancreaticobiliary duct opening at the ampulla of Vater. By injecting contrast dye through the scope, ERCP allows visualization of the pancreato-biliary system, enabling precise identification of stone count, location, assessment of biliary pressure, and evaluation of the papilla’s function. ERCP offers advantages such as minimal invasiveness and rapid recovery[9]. However, it is a technically demanding procedure with a relatively high risk of complications, ranging from 5% to 10%[10]. Common complications following ERCP include wound infection, pancreatitis, cholangitis, hemorrhage, perforation, and hyperamylasemia, which can significantly affect patients’ postoperative recovery and overall well-being, limiting its clinical use[10-12]. To improve surgical outcomes, clinicians often use biliary stenting to reduce biliary pressure, support wound healing, and facilitate inflammation resolution while aiding in the removal of residual stones from the bile duct.

Stent drainage procedures include both standard biliary drainage and endoscopic retrograde biliary drainage (ERBD)[13]. The Christmas tree-shaped plastic stent is commonly used in clinical practice for biliary drainage due to its low risk of spontaneous detachment. Guidelines[14] recommend removal after 3 to 6 months; however, repeated removals may increase treatment costs, psychological burden, and the risk of complications. Research has shown that endoscopic nasobiliary drainage (ENBD) is a minimally invasive and relatively straightforward endoscopic technique that can achieve bile duct drainage outcomes comparable to traditional surgery, with minimal trauma and endoscopic intervention, while potentially reducing the risk of complications following ERCP[15]. Park et al[16] reported that using pancreatic plastic stents for biliary internal drainage resulted in significant drainage outcomes. Similarly, a study by He et al[17] demonstrated that modified pancreatic stents effectively prevented post-ERCP pancreatitis, with a self-removal rate of 84.21% after 14 days.

Currently, there is no standardized consensus on the optimal surgical approach for biliary drainage in clinical practice, highlighting the need for further research to establish a unified strategy. Additionally, no multidimensional comparative analysis has been conducted to evaluate the clinical efficacy of using a modified pancreatic duct plastic stent for ERBD or ENBD and a Christmas tree-shaped plastic stent for standard biliary drainage following ERCP for bile duct stone removal. Therefore, in this study, we compared the clinical efficacy of the modified pancreatic duct plastic stent for ERBD, ENBD, and Christmas tree-shaped plastic stents in ERCP for treating common bile duct stones. We aim to explore the effectiveness of the improved pancreatic duct plastic stent in patients with ERCP and its impact on postoperative complications, thereby identifying the most suitable drainage technique after ERCP for common bile duct stones and improving patient outcomes.

MATERIALS AND METHODS

Patients

This retrospective study included 175 patients with choledocholithiasis admitted to Taizhou Fourth People’s Hospital between January 1, 2021, and November 30, 2023. The patients were divided into three groups-the modified pancreatic duct stent drainage group (using ERBD technology, n = 59), the nasobiliary drainage group (using ENBD technology, n = 58), and the standard biliary drainage group (using Christmas tree-shaped stent, n = 58). The patient inclusion process is graphically illustrated in Figure 1.

Figure 1 Flow chart of management.

The inclusion criteria were as follows: Diagnosis of choledocholithiasis according to the 2019 European Society of Gastrointestinal Endoscopy clinical practice guidelines[18]; confirmation of gallstones in the biliary ducts through histopathological examination or imaging techniques, such as laparoscopy[19]; pre-treatment abdominal pain of varying degrees, with a visual analog scale (VAS) score of 5 or higher; adherence to treatment protocols; and all surgeries performed by the same surgical team. Patients were excluded if they had any of the following: Significant organ dysfunction (heart, liver, or kidney), not meeting the indications for ERCP, severe digestive system impairment, concurrent malignant tumors, or poor compliance or refusal to participate.

Approaches to intervention

Surgical equipment: The following surgical equipment was utilized during the interventions: An electronic duodenoscope (TJF260V by Olympus Corporation, Japan), guidewire (Yellow Stripe, 0.035 inches or 4500 mm, Nanjing Minimally Invasive Medical Technology Co., Ltd.), papillotome (Medi-Globe GmbH), forceps, balloon catheter (Nanjing Minimally Invasive Medical Technology Co., Ltd.), stone retrieval basket (Cook Medical), Christmas tree-shaped plastic stent (8.5 Fr, Nanjing Minimally Invasive Medical Technology Co., Ltd.), standard nasobiliary drainage tube (NBDS-B-7/250-P, Nanjing Minimally Invasive Medical Technology Co., Ltd.), and a modified pancreatic duct stent (SPSOF-7-5, Cook Medical).

ERCP procedure: All patients underwent routine blood tests, liver and kidney function assessments, coagulation function evaluations, and imaging examinations 24 hours before the operation. They were required to fast and refrain from food and water for at least 6 hours before the operation. After positioning the patients prone, they received routine anesthesia and analgesia. The endoscope was then inserted through the mouth to reach the duodenal papilla. Selective choledochal intubation was performed using a papillotome knife with a guidewire, followed by an injection of a 20% iophedronol contrast. The choledochal ducts were observed using C-arm fluoroscopy. During the procedure, endoscopic sphincterotomy and endoscopic balloon dilatation were performed based on the location and size of the stones, as well as the diameter of the bile duct. After stone extraction using a balloon or mesh basket, re-imaging was performed to confirm the complete clearance of the stones.

Drainage procedure: In the modified pancreatic duct stent drainage group, following cholecystectomy for gallstones and ERBD, a modified pancreatic duct plastic stent (COOK Company) was inserted into the pancreatic duct. Correct placement of the stent was confirmed using intraoperative C-arm fluoroscopy. The papilla and the field of vision were free from active hemorrhage, and the endoscope was removed, marking the completion of the procedure.

In the nasobiliary drainage group, following choledochal stone extraction, an NBDS-B-7/250-P (Nanmicro Medical Technology Co., Ltd.) was inserted into the choledochus under the guidance of a guidewire. ENBD was performed. The tip of the nasobiliary tube was positioned at the openings of the left and right hepatic ducts, allowing bile outflow. C-arm fluoroscopy was used to confirm that the nasobiliary drainage tube was securely placed. The papilla and field of view were examined, revealing no active hemorrhage. The procedure was concluded by retracting the endoscope.

In the standard biliary drainage group, following choledochal stone extraction, a BPDS-13442-0807/22 Christmas tree-shaped stent (Nanjing Microtronics) was inserted into the choledochal duct for biliary drainage. C-arm fluoroscopy was used to confirm that the stent was securely placed. An examination of the papilla and the visual field showed no active hemorrhage. The procedure was concluded with the removal of the endoscope. Postoperatively, the patient’s vital signs and condition should be closely monitored. Additionally, liver function, blood routine, amylase, C-reactive protein (CRP), and other relevant indices should be retested as needed. Supportive treatments, such as anti-infection measures, acid suppression, enzyme suppression, and fluid rehydration, should also be administered.

Indicator collection

General information: This study recorded and compared various parameters among the three patient groups, including age, gender, body mass index (BMI), history of alcohol consumption, time of disease onset before surgery, total hospital stay duration, disease duration, American Society of Anesthesiologists (ASA) classification, surgical duration, bile duct diameter, stone diameter, and the number of gallstones in the bile duct.

ASA classification standards[20] are as follows: Class I refers to a physically healthy individual with normal organ function; Class II describes a patient with mild systemic diseases and a surgical condition but with preserved compensatory mechanisms; Class III indicates a patient with severe systemic diseases that limits physical activity but does not preclude daily functioning; Class IV applies to a patient with severe systemic disease that is life-threatening; Class V refers to a critically ill patient who is unlikely to survive without surgical intervention; and Class VI designates a deceased patient whose organs are being prepared for transplantation.

Laboratory indicators and questionnaire surveys

Laboratory indicators, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), total bilirubin (TBIL), direct bilirubin (DBIL), CRP, white blood cells (WBC), hemoglobin (Hb), neutrophils (NEU), and amylase (AMY), were measured and compared across the three patient groups before and 24 hours after drainage surgery. Pain levels were evaluated using a VAS, and postoperative complications, such as pancreatitis, cholangitis, hemorrhage, perforation, wound infection, hyperamylasemia, and mortality, were recorded.

The VAS scoring scale[21]: The scale ranges from 1 to 10, where a score of 3 or below indicates mild or no pain, a score of 4 to 6 reflects significant pain that may impact sleep, and a score of 7 or above represents severe pain with a significant impact on sleep and appetite.

Pancreatitis: This is defined by at least two of the following revised Atlanta criteria[22]: (1) Persistent upper abdominal pain attributable to pancreatitis; (2) A threefold or more significant increase in amylase or lipase levels within 24 hours postsurgery; or (3) Characteristic imaging findings on computed tomography (CT) scans, such as pancreatic enlargement, necrosis, or peripancreatic fluid collection.

Severe pancreatitis: This is characterized by peripancreatic fluid collections and/or pleural and peritoneal effusions on abdominal CT scans[23], requiring management with percutaneous catheter drainage or surgical intervention.

Cholangitis: Fever (temperature > 38 °C) occurring within 24 hours postsurgery, accompanied by elevated WBC count and abdominal pain, with no evidence of infection at another site[24].

Hemorrhage: Symptoms include black stool or hematemesis within 24 hours postsurgery, fresh blood in the nasobiliary drainage tube, and a drop in blood pressure, necessitating endoscopic hemostasis.

Perforation: Following surgery, the patient experienced worsening abdominal pain within 24 hours. Upon imaging confirmation of a perforation, the patient was managed with a medically supervised fasting regimen, gastrointestinal decompression, and antibiotic therapy for infection control. In cases of extensive perforation, prompt surgical intervention was deemed necessary.

Wound infection: Obvious redness and oozing at the surgical incision site within 24 hours postsurgery, necessitating aggressive antibiotic treatment, along with concurrent physiotherapy and other supportive care.

Hyperamylasemia: A postsurgery increase in blood amylase levels exceeding three times the upper normal limit, occurring within 24 hours without fever or abdominal pain symptoms.

Statistical analysis

Statistical analysis was conducted using IBM Statistics Version 27.0.1 (SPSS Inc., Beijing, China). In the patients’ general information, gender, history of alcohol consumption, ASA classification, number of gallstones in the bile duct, and complication rates were all categorical data presented as n (%). Since the gender, ASA classification, and complication rates had theoretical frequencies > 5 and a total sample size of at least 40, Pearson’s χ² test was applied. For the number of gallstones in the bile duct, data satisfying 1 ≥ theoretical frequency ≥ 5 and a total sample size of at least 40 were analyzed using the continuity-corrected χ² test (Yates’ correction). Continuous data were initially analyzed for normal distribution using histograms and the Shapiro-Wilk test for single samples. In the patients’ general information, variables such as age, BMI, time of disease onset before surgery, total hospital stay duration, disease duration, surgical duration, bile duct diameter, stone diameter, and all laboratory indicators, as well as VAS scores, were normally distributed and represented as (mean ± SD). The AST, ALT, ALP, GGT, TBIL, DBIL, CRP, WBC, Hb, NEU, and AMY indicators met the assumption of homoscedasticity. These variables were compared using a one-way analysis of variance (ANOVA) across the three groups. Pairwise comparisons were performed using the least significant difference t-test for all comparisons, and a one-way ANOVA with repeated measures was used to compare data collected 24 hours before and after surgery within each group. Differences were considered statistically significant when P < 0.05.

RESULTS

Comparison of the general clinical data of the three patient groups

Between January 1, 2021, and November 30, 2023, 175 patients with common bile duct stones successfully underwent ERCP treatment. Among them, 59 patients (33.71%) used pancreatic stent drainage, 58 patients (33.14%) employed nasobiliary drainage, and 58 patients (33.14%) utilized biliary stent drainage.

The baseline characteristics of all patients, including age, gender, BMI, history of alcohol consumption, time of disease onset before surgery, total hospital stay duration, disease duration, ASA classification, surgical duration, bile duct diameter, stone diameter, and the number of gallstones in the bile duct, are presented in Table 1. There were no statistically significant differences among the three patient groups (P > 0.05) (Table 1).

Table 1 The general clinical data of the three groups of patients were compared.

	Modified pancreatic duct stent drainage group (n = 59)	Nasobiliary drainage group (n = 58)	Standard biliary drainage group (n = 58)	χ2/F value	P value
Gender (male/female)	35 (59.32)/24 (40.68)	33 (56.90)/25 (43.10)	32 (55.17)/26 (44.83)	0.208	0.901
ASA classification (I/II/III)	22 (37.29)/28 (47.46)/9 (15.25)	11 (18.97)/36 (62.07)/11 (18.97)	16 (27.59)/32 (54.24)/10 (17.24)	4.887	0.299
The number of gallstones in the bile duct (1/2/3/≥ 4)	29 (49.15)/7 (11.86)/5 (8.47)/18 (30.51)	28 (48.28)/5 (8.62)/5 (8.62)/20 (34.48)	23 (39.66)/6 (10.34)/5 (8.62)/24 (41.38)	2	0.92
Age (year)	51.42 ± 15.14	52.00 ± 16.08	51.84 ± 15.84	0.021	0.979
BMI (kg/m2)	23.34 ± 3.82	23.29 ± 3.67	23.16 ± 3.54	0.037	0.964
History of drinking (yes/no)	26 (44.07)/33 (55.93)	24 (41.38)/34 (58.62)	23 (39.66)/35 (60.34)	0.238	0.888
Time of onset before surgery (hours)	35.51 ± 3.25	35.94 ± 3.58	36.10 ± 4.33	0.389	0.678
Total hospital stay duration (days)	9.12 ± 4.34	10.62 ± 5.06	11.04 ± 5.13	2.536	0.082
Disease duration (month)	21.14 ± 4.28	22.04 ± 4.05	21.67 ± 3.94	0.715	0.491
Surgical duration (minutes)	61.04 ± 8.91	60.55 ± 6.42	60.07 ± 7.49	0.233	0.792
Diameter of the bile duct (cm)	1.34 ± 0.43	1.31 ± 0.48	1.38 ± 0.51	0.318	0.728
Stone diameter (cm)	0.86 ± 0.35	0.88 ± 0.36	0.91 ± 0.43	0.254	0.776

Results expressed as mean ± SD, or the number of patients and percentage (%). ASA: American Society of Anesthesiologists; BMI: Body mass index.

Comparison of laboratory indicators between the three patient groups 24 hours before and after surgery

There were no statistically significant differences in serum levels of AST, ALT, ALP, GGT, TBIL, DBIL, CRP, WBC, Hb, NEU, and AMY among the three patient groups 24 hours before surgery (all P > 0.05).

However, serum levels of AST, ALT, ALP, GGT, TBIL, DBIL, CRP, WBC, Hb, NEU, and AMY in all three patient groups significantly decreased 24 hours after surgery compared to 24 hours before surgery (all P < 0.05) (Table 2).

Table 2 Comparison of laboratory indicators among three groups of patients, mean ± SD.

	Modified pancreatic duct stent drainage group (n = 59)	Nasobiliary drainage group (n = 58)	Standard biliary drainage group (n = 58)	F value	P value	P1 value	P2 value	P3 value
AST (U/L)
24 hours before the surgery	58.38 ± 18.49	55.71 ± 20.07	55.75 ± 20.84	0.217	0.642
24 hours after the surgery	29.28 ± 3.47	48.64 ± 4.37	30.13 ± 3.88	449.671	< 0.001	< 0.001	< 0.001	0.240
ALT (U/L)
24 hours before the surgery	85.36 ± 6.41	83.15 ± 6.74	84.28 ± 6.69	0.221	0.639
24 hours after the surgery	35.44 ± 4.73	68.54 ± 5.58	36.49 ± 6.33	650.159	< 0.001	< 0.001	< 0.001	0.294
ALP (U/L)
24 hours before the surgery	160.42 ± 35.48	159.45 ± 34.82	158.47 ± 31.82	1.153	0.284
24 hours after the surgery	133.09 ± 33.21	153.14 ± 36.58	134.54 ± 31.25	6.390	0.002	0.002	0.003	0.837
GGT (U/L)
24 hours before the surgery	383.45 ± 106.82	364.58 ± 119.42	322.84 ± 128.94	0.402	0.527
24 hours after the surgery	252.64 ± 44.52	294.59 ± 51.60	255.52 ± 55.31	12.314	< 0.001	< 0.001	< 0.001	0.668
TBIL (mol/L)
24 hours before the surgery	28.65 ± 6.77	28.94 ± 6.82	28.59 ± 5.82	1.603	0.207
24 hours after the surgery	16.08 ± 3.38	24.36 ± 4.16	16.18 ± 3.67	94.115	< 0.001	< 0.001	< 0.001	0.878
DBIL (mol/L)
24 hours before the surgery	12.53 ± 3.56	13.05 ± 3.81	13.34 ± 3.64	3.165	0.077
24 hours after the surgery	8.59 ± 2.14	9.93 ± 2.42	8.96 ± 2.57	5.213	0.006	0.002	0.032	0.328
CRP (mg/L)
24 hours before the surgery	104.58 ± 5.89	102.57 ± 6.68	101.53 ± 5.46	2.516	0.115
24 hours after the surgery	83.65 ± 6.91	96.08 ± 7.04	84.53 ± 6.31	62.572	< 0.001	< 0.001	< 0.001	0.311
WBC (× 109/L)
24 hours before the surgery	11.28 ± 5.94	10.64 ± 4.58	10.53 ± 5.08	0.089	0.766
24 hours after the surgery	9.51 ± 4.41	9.46 ± 5.02	9.48 ± 4.66	0.003	0.997	0.942	0.984	0.959
Hb (g/L)
24 hours before the surgery	133.54 ± 20.19	134.48 ± 20.25	134.82 ± 20.72	2.171	0.143
24 hours after the surgery	123.14 ± 19.58	124.15 ± 18.24	123.31 ± 18.94	0.043	0.958	0.796	0.805	0.992
NEU (%)
24 hours before the surgery	0.78 ± 0.14	0.79 ± 0.13	0.78 ± 0.15	0.627	0.430
24 hours after the surgery	0.73 ± 0.08	0.76 ± 0.09	0.74 ± 0.07	1.337	0.265	0.157	0.159	0.999
AMY (IU/L)
24 hours before the surgery	281.26 ± 94.15	274.59 ± 93.08	268.42 ± 99.81	1.116	0.292
24 hours after the surgery	121.46 ± 44.28	175.83 ± 46.82	127.43 ± 41.08	26.653	< 0.001	< 0.001	< 0.001	0.432

P1 represents the comparison between the modified pancreatic duct stent drainage group and nasobiliary drainage group. P2 represents the comparison between the nasobiliary drainage group and standard biliary drainage group. P3 represents the comparison between the standard biliary drainage group and modified pancreatic duct stent drainage group. AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; ALP: Alkaline phosphatase; GGT: Gamma-glutamyltransferase; TBIL: Total bilirubin; DBIL: Direct bilirubin; CRP: C-reactive protein; WBC: White blood cells; Hb: Hemoglobin; NEU: Neutrophils; AMY: Amylase.

After adjusting for preoperative variables, different drainage methods significantly affected the changes in serum levels of AST, ALT, ALP, GGT, TBIL, DBIL, CRP, and AMY. Post-treatment comparisons showed that the modified pancreatic duct stent drainage group had significantly lower AST, ALT, ALP, GGT, TBIL, DBIL, CRP, and AMY serum levels than the nasobiliary drainage group (P < 0.05). Similarly, the serum levels of AST, ALT, ALP, GGT, TBIL, DBIL, CRP, and AMY in the standard biliary drainage group were significantly lower than those in the nasobiliary drainage group, with a statistically significant difference (P < 0.05). There were no statistically significant differences in serum levels of AST, ALT, ALP, GGT, TBIL, DBIL, CRP, and AMY between patients in the standard biliary drainage group and those in the nasobiliary drainage group (P < 0.05). Additionally, no statistically significant differences were found in two-by-two comparisons of WBC, Hb, and NEU indicators among the three patient groups (all P > 0.05) (Table 2).

Comparison of VAS scores between the three patient groups 24 hours before and after surgery

There was no statistically significant difference in VAS scores (F = 0.077, P = 0.781) 24 hours before surgery among the three patient groups. However, statistically significant differences in the VAS scores were observed among the three patient groups 24 hours after surgery (F = 10.416, P < 0.001) (Table 3). Preoperative covariates had no significant impact on the corresponding indicators in the three patient groups (P = 0.781).

Table 3 Comparison of visual analogue scale scores among the three groups of patients, mean ± SD.

	Modified pancreatic duct stent drainage group (n = 59)	Nasobiliary drainage group (n = 58)	Standard biliary drainage group (n = 58)	F value	P value	P1 value	P2 value	P3 value
VAS (point)
24 hours before the surgery	6.25 ± 2.16	6.24 ± 2.45	6.26 ± 2.54	0.077	0.781
24 hours after the surgery	4.36 ± 1.18	5.54 ± 1.24	4.92 ± 1.68	10.416	< 0.001	< 0.001	0.017	0.033

P1 represents the comparison between the modified pancreatic duct stent drainage group and nasobiliary drainage group. P2 represents the comparison between the nasobiliary drainage group and standard biliary drainage group. P3 represents the comparison between the standard biliary drainage group and modified pancreatic duct stent drainage group. VAS: Visual analogue scale.

VAS scores in all three groups significantly decreased 24 h after surgery compared to 24 hours before surgery (P < 0.05) (Table 3).

After adjusting for preoperative VAS scores, significant differences were found in VAS score changes between different drainage methods (P < 0.001). Post-hoc comparisons revealed that VAS scores in the modified pancreatic duct stent drainage group were significantly lower than those in the nasobiliary drainage group (P < 0.05). Similarly, VAS scores in the modified pancreatic duct stent drainage group were significantly lower than those in the standard biliary drainage group (P = 0.033). Finally, the standard biliary drainage group had significantly lower VAS scores than the nasobiliary drainage group (P = 0.017) (Table 3).

Comparison of complication rates across the three patient groups

There was no statistically significant difference in complication rates among the three patient groups (P = 0.336) (Table 4).

Table 4 Comparison of complication occurrence in three groups of patients.

	Modified pancreatic duct stent drainage group (n = 59)	Nasobiliary drainage group (n = 58)	Standard biliary drainage group (n = 58)	χ2 value	P value
Complications	14 (23.73)	18 (31.03)	21 (36.21)	2.180	0.336
Pancreatitis	1 (1.69)	0 (0.00)	0 (0.00)
Cholangitis	0 (0.00)	1 (1.72)	0 (0.00)
Hemorrhage	0 (0.00)	2 (3.45)	2 (3.45)
Perforation	1 (1.69)	0 (0.00)	1 (1.72)
Wound infection	0 (0.00)	0 (0.00)	1 (1.72)
Hyperamylasemia	12 (20.34)	15 (25.86)	17 (29.31)
Death	0 (0.00)	0 (0.00)	0 (0.00)

The number of patients and percentage (%).

DISCUSSION

Our study found that the modified pancreatic duct stent in ERCP treatment for patients with bile duct stones effectively reduced hepatocyte injury, improved liver function, alleviated inflammation and pain, enhanced patient comfort, and a higher level of safety compared to standard biliary drainage and nasobiliary drainage methods.

After performing ERCP lithotripsy, both domestic and international units commonly use ENBD and ERBD to reduce the risk of postoperative cholangitis and to lower the rate of postoperative pancreatitis[25-27]. Numerous randomized control trial studies have found no significant difference in bile drainage effectiveness or complications between biliary stents and ENBD[28-31], largely due to the fundamental principles of these two methods. ENBD, as an external drainage method, allows for the objective evaluation of drainage effectiveness through bile output volume and composition, facilitating better patient monitoring and management, particularly for thick bile. Furthermore, it reduces the risk of drainage tube blockage and insufficient drainage[32]. However, ENBD has its limitations. Its insertion involves a tube through the nasal passage, which may cause electrolyte imbalances and digestive issues if left in place for extended periods[33]. The tube can cause discomfort in the nasal and pharyngeal regions, local swelling, and hemorrhage, potentially increasing the risk of respiratory infections[33]. Meanwhile, ERBD, a newer drainage method, achieves bile drainage by inserting a biliary stent. It is generally more comfortable than ENBD. During the treatment of common bile duct stones, ERBD may facilitate stone reduction and improve postoperative outcomes by promoting gut nutrition[34]. Additionally, due to its stable design with cedar-like wings at the head end and the absence of side holes, the Christmas tree-shaped plastic stent enhances drainage patency and reduces the risk of retrograde infection. However, most plastic stents in the common bile duct cannot be dislodged independently and must be pulled out under endoscopy, increasing patients’ discomfort and medical costs[35,36].

Cholelithiasis of the common bile duct can lead to obstruction of the hepatic bile duct circulation, causing liver cell injury and surrounding tissue damage, as evidenced by elevated liver function parameters, such as AST, ALT, ALP, GGT, TBIL, and DBIL[37,38]. Our study findings indicated that the postoperative levels of these markers were significantly lower in all three patient groups than preoperative values. However, both the modified pancreatic duct stent drainage group and the standard biliary drainage group had significantly lower levels of AST, ALT, ALP, GGT, TBIL, and DBIL than the nasobiliary drainage group. This indicates that all three drainage methods effectively alleviate intraductal pressure, facilitate bile flow, and reduce liver function impairment and bile metabolism abnormalities, thereby improving hepatobiliary function. Our results were consistent with Mangiavillano et al’s research[39], which showed that modified pancreatic duct plastic stent drainage and standard biliary stent drainage were more effective in reducing liver cell injury and improving liver function in patients with common bile duct stones undergoing ERCP. This may be because placing the tube through the patient’s nostril enables ENBD to reduce bile duct pressure and facilitates adequate drainage. However, prolonged nasal drainage could lead to bile loss and impair digestive function, hindering liver function recovery. Conversely, the biliary plastic stent placement aligns more closely with human anatomy, causing less discomfort to the throat and respiratory system. It maintains bile duct patency, effectively draining the pus and minimizing liver cell damage, which promotes recovery of liver function[39].

Elevated WBC is a traditional diagnostic indicator for bacterial infections; however, it is not a specific toxicological marker, as it can also be elevated due to granulocyte colony-stimulating factors, cytokines, and, in some inflammatory conditions, may even decrease[40]. NEU plays a crucial role in defending against bacteria by engulfing them, and an increased NEU level indicates bacterial infection and heightened inflammation[41]. CRP, an acute-phase response protein, helps clear pathogens and necrotic cells from the body, aiding the immune response. CRP levels significantly rise in response to tissue injury, inflammation, or postsurgery[42]. AMY activity tests are clinically used to diagnose acute pancreatitis and can also assist in differentiating between other acute abdominal conditions, such as abdominal pain, rigidity, nausea, and vomiting[43]. Our study findings showed that after surgery, all three patient groups had significantly lower levels of WBC, Hb, and NEU than before surgery. CRP and AMY serum levels were significantly lower in the modified pancreatic duct stent drainage and standard biliary drainage groups than in the nasobiliary drainage group. This indicates that all groups experienced a trend toward improved inflammatory markers after cholecystectomy. However, compared to ENBD, both the modified pancreatic duct plastic stent and conventional biliary stent drainage were more effective in alleviating inflammation in patients undergoing ERCP for gallstone disease. This may be because biliary drainage induces autophagy in the intestinal mucosa, reducing the expression of inflammatory factors and thus mitigating inflammation[44]. Conversely, ENBD, with its prolonged nasal bile drainage, can lead to bile loss and intestinal mucosa damage, impairing autophagy and hindering the regulation of inflammatory factor expression.

Our study findings indicated that VAS scores in the modified pancreatic duct stent drainage group were significantly lower than those in the standard biliary drainage group, which had lower VAS scores than the nasobiliary drainage group. This indicates that pain symptoms were alleviated in all three patient groups with common bile duct stones following ECRP treatment. However, the modified pancreatic duct plastic stent offered more effective pain relief and improved comfort than the ENBD and standard biliary stents. This finding aligns with the findings of Longo et al[45]. The likely reason is that the modified pancreatic duct plastic stent better aligns with the human physiological structure, reducing nasopharynx stimulation associated with tube retention and minimizing discomfort related to the throat and respiratory system. The expert consensus on accelerated recovery after hepatobiliary and pancreatic surgery (2015 edition) highlights that the basic principle of accelerated recovery surgery is to reduce the stress response[46]. The earlier introduction of oral intake and fluids in the modified pancreatic duct stent group postsurgery aligns with this concept, promoting gastrointestinal function recovery, reducing intestinal stress, and minimizing fluid overload[47]. Additionally, the placement of the pancreatic stent effectively prevents bile reflux into the pancreas, preventing premature activation of pancreatic enzymes, enabling proper pancreatic fluid drainage, lowering intraductal pressure, and reducing pancreatic fluid infiltration into glandular tissue. This helps prevent self-digestion of the pancreas and alleviates patient pain[48].

Our study findings further showed no statistically significant difference in complication rates among the three groups, indicating that the three drainage methods had a similar impact on complications after ECRP for patients with common bile duct stones. This could be due to the modified pancreatic stent having the same diameter as the nasobiliary tube, enabling effective drainage and reducing the risk of early detachment, which could lead to drainage failure. Additionally, our study demonstrated that ERBD facilitated stone removal by causing the stent to move along with intestinal contractions, potentially breaking the stones into smaller pieces. Some stones are even fractured into multiple parts, making them easier to retrieve during subsequent procedures. Additionally, the single pigtail structure at the end of the modified 7Fr pancreatic stent helped prevent proximal displacement and reduced pressure on the intestinal mucosa, reducing the risk of biliary duct or duodenum perforations. By modifying the bile duct end to remove lateral wings, the study showed a higher likelihood of spontaneous detachment, a lower need for manual intervention, and sufficient drainage without the risk of prolonged stent retention, which could cause biliary obstruction, injury, or cholangitis[49].

Malpositioning and occlusion of the stent are common reasons for failed drainage following stent placement. The stent should be positioned within the dilated bile duct, ideally above the stone, with its proximal end extending at least 1 cm above the rim of the stone and its distal end located 1 cm beyond the papilla of Vater. Temporary narrowing of the biliary tract may occur during stent placement, which, while inevitable, is necessary for a smooth procedure. When selecting a biliary stent, it is important to consider factors such as effective drainage, preferably opting for a larger-diameter stent. In cases of recurrent jaundice or cholecystitis, the stent should be promptly removed and replaced with a new stent[50].

This study found that the modified pancreatic duct plastic stent effectively addresses the limitations of ENBD and standard biliary stent implantation, reducing the risk of displacement during drainage. This might be because it could better conform to the physiological structure of the human body. However, patients with this stent had a higher risk of cholangitis, potentially due to its reduced flexibility and the need for endoscopic resection.

This study has several limitations. First, it is a single-center study with a small sample size, a short follow-up period, and potential confounding factors. Second, the timing of laboratory assessments was not strictly controlled, and there was a lack of both short- and long-term data on patients’ satisfaction with the drainage method. These limitations may introduce bias into the findings, highlighting the need for further multi-center, large-sample, prospective, and long-term follow-up studies to validate the results.

CONCLUSION

In conclusion, the use of modified pancreatic duct plastic stent drainage as an adjunct to post-ERCP treatment for choledochal stones effectively alleviated patients’ pain, did not significantly affect the occurrence of postoperative complications, and demonstrated a higher safety profile. Compared to ENBD and standard biliary stenting, the modified pancreatic duct plastic stent drainage reduced liver cell injury, improved liver function parameters, alleviated inflammation and pain, enhanced comfort, accelerated recovery, and improved quality of life. Its clinical value is substantial, leading to its recommendation for broader application in ERCP treatment for patients with choledochal stones. We suggest that the modified pancreatic duct plastic stent be considered the first choice for post-ERCP drainage in these patients.