Cholangioscope-Assisted Endoscopic Retrograde Appendicitis Therapy in the Management of Chronic Abdominal Pain Related to the Appendix: A Single-Center Retrospective Study
Chronic abdominal pain is common in adults, with many patients having unknown causes and recurrent pain that impacts daily functioning . Physicians diagnose these patients with functional abdominal pain; however, this leads to some patients being misdiagnosed . Research shows that appendiceal fecal stones or chronic appendicitis are associated with some cases of chronic abdominal pain, but diagnosis and treatment have always been challenging . In the past, an appendectomy was the main treatment method for suspected chronic abdominal pain related to the appendix, but there were risks such as negative appendectomy, surgical site infection, and intestinal fistula . In recent years, endoscopic retrograde appendicitis therapy (ERAT) has been widely used to treat acute uncomplicated appendicitis, especially with the assistance of cholangioscopy . Cholangioscope-assisted ERAT can be used to view the appendiceal cavity directly for flushing, stone removal, biopsy, and other operations, thereby achieving precise treatment. The purpose of this study was to investigate the efficacy and safety of cholangioscope-assisted ERAT in the treatment of chronic abdominal pain related to the appendix. 

Patient Data A retrospective analysis was conducted on patients who underwent cholangioscope-assisted ERAT procedures in our hospital due to chronic abdominal pain related to the appendix from January 2023 to January 2024. The inclusion criteria were as follows: 1) Chronic abdominal pain patients aged 14–75 years with abdominal pain located around the periumbilical region and/or in the right lower abdomen. The course of abdominal pain was more than 3 months, and there were at least 3 or more episodes of abdominal pain during the course of the disease. 2) Preoperative abdominal CT suggested fecal stones in the appendix and/or inflammatory lymph nodes around the appendix, without acute appendicitis symptoms such as thickening of the appendix or exudation around the appendix. A clinical diagnosis of chronic abdominal pain related to the appendix was made in patients whose symptoms were combined with the above CT signs. The exclusion criteria were as follows: (1) patients who were currently diagnosed with acute appendicitis and had a clear history of acute appendicitis in the past. (2) Appendiceal gangrene perforation, diffuse peritonitis, or a periappendiceal abscess. (3) Patients with contraindications for colonoscopy examination. (4) Pregnant patients and those with concomitant organic diseases of the digestive tract, such as intestinal malignant tumors, intestinal ulcers, and ischemic bowel disease. (5) Patients who refused to provide informed consent. The study was approved by our hospital’s Ethics Committee (Approval No. KYLLKS20240147). Cholangioscope-Assisted ERAT Procedure The routine bowel preparations for standard colonoscopic examination were performed before the procedure. Patients were placed in the left lateral decubitus position. A colonoscope (CF-HQ290I: Olympus, Tokyo, Japan; 3.7 mm channel diameter) with a short transparent cap attached at the tip was inserted into the cecum. The shape of the opening of the appendix and the surrounding mucosa was observed to determine whether there was congestion, edema, or pus outflow. The opening of the appendix was exposed with a transparent cap. The imaging catheter used for cholangioscopy (Nanjing Nanwei Medical Technology Co., Ltd., China, instrument channel diameter of ≥ 1.0 mm and effective working length of 2200 ± 50 mm) was subsequently inserted into the opening of the appendix through the colonoscopy channel. The Gerlach valve was pushed with the front end of the catheter. By adjusting the spiral of the cholangioscopy, the catheter could easily enter the appendiceal cavity. If there were fecal stones or fecal residue in the appendix cavity, the appendix lumen was rinsed repeatedly with normal saline. The details are illustrated in Fig. . If the fecal stones were large, hard, or embedded, a net basket was used under direct vision to remove them. For patients with severe inflammation and strictures, an indwelling appendix plastic stent was placed for drainage (8.5 Fr–7 cm stent). Under cholangioscopy, the stent was placed as follows: 1) A guide wire was inserted into the blind end of the appendix under cholangioscopy. 2) Then, the cholangioscope was removed while keeping the guide wire in the appendiceal cavity. 3) Under the guidance of the guide wire, the 8.5 Fr–7 cm stent was slowly advanced along the guide wire into the lumen of the appendiceal orifice. By employing this method, the plastic stent was precisely placed within the appendiceal cavity, which could facilitate continuous expansion and drainage. The stent was usually removed via colonoscopy at 3 months after the procedure. None of the patients were treated with antibiotics except for those diagnosed with acute appendicitis following the endoscopic-assisted ERAT procedure. Follow-Up The occurrence of complications within 24 and 48 h postoperatively mainly included worsening abdominal pain, fever, vomiting, etc. After discharge, telephone follow-up was conducted every 3 months to assess the relief of abdominal pain in patients, with a minimum follow-up period of 6 months. Definition The technical success rate was defined as successful intubation of the imaging catheter, including entry into the appendiceal lumen and direct visualization of the blind end of the appendix accompanied by the removal of fecal stones in the appendix cavity along with lavage, dilation, and drainage. The clinical success rate referred to the complete disappearance of preoperative clinical symptoms and normalization of inflammatory indicators (leukocytes, neutrophil percentage, etc.). The degree of abdominal pain was assessed via a visual analog scale (VAS). A score of 0 in this VAS represents no pain, and a score of 10 represents extremely severe pain. The mean procedure time was defined as the time from the beginning of intubation into the appendix to the exit of the appendix cavity after treatment. Statistical Analysis Statistical analysis was performed using IBM SPSS Statistics v22.0 (Social Science Statistics Package, Inc., Chicago, IL, USA). The mean ± standard deviation was used for quantitative variables, and the percentage (%) was used for qualitative variables. 

A retrospective analysis was conducted on patients who underwent cholangioscope-assisted ERAT procedures in our hospital due to chronic abdominal pain related to the appendix from January 2023 to January 2024. The inclusion criteria were as follows: 1) Chronic abdominal pain patients aged 14–75 years with abdominal pain located around the periumbilical region and/or in the right lower abdomen. The course of abdominal pain was more than 3 months, and there were at least 3 or more episodes of abdominal pain during the course of the disease. 2) Preoperative abdominal CT suggested fecal stones in the appendix and/or inflammatory lymph nodes around the appendix, without acute appendicitis symptoms such as thickening of the appendix or exudation around the appendix. A clinical diagnosis of chronic abdominal pain related to the appendix was made in patients whose symptoms were combined with the above CT signs. The exclusion criteria were as follows: (1) patients who were currently diagnosed with acute appendicitis and had a clear history of acute appendicitis in the past. (2) Appendiceal gangrene perforation, diffuse peritonitis, or a periappendiceal abscess. (3) Patients with contraindications for colonoscopy examination. (4) Pregnant patients and those with concomitant organic diseases of the digestive tract, such as intestinal malignant tumors, intestinal ulcers, and ischemic bowel disease. (5) Patients who refused to provide informed consent. The study was approved by our hospital’s Ethics Committee (Approval No. KYLLKS20240147). 

The routine bowel preparations for standard colonoscopic examination were performed before the procedure. Patients were placed in the left lateral decubitus position. A colonoscope (CF-HQ290I: Olympus, Tokyo, Japan; 3.7 mm channel diameter) with a short transparent cap attached at the tip was inserted into the cecum. The shape of the opening of the appendix and the surrounding mucosa was observed to determine whether there was congestion, edema, or pus outflow. The opening of the appendix was exposed with a transparent cap. The imaging catheter used for cholangioscopy (Nanjing Nanwei Medical Technology Co., Ltd., China, instrument channel diameter of ≥ 1.0 mm and effective working length of 2200 ± 50 mm) was subsequently inserted into the opening of the appendix through the colonoscopy channel. The Gerlach valve was pushed with the front end of the catheter. By adjusting the spiral of the cholangioscopy, the catheter could easily enter the appendiceal cavity. If there were fecal stones or fecal residue in the appendix cavity, the appendix lumen was rinsed repeatedly with normal saline. The details are illustrated in Fig. . If the fecal stones were large, hard, or embedded, a net basket was used under direct vision to remove them. For patients with severe inflammation and strictures, an indwelling appendix plastic stent was placed for drainage (8.5 Fr–7 cm stent). Under cholangioscopy, the stent was placed as follows: 1) A guide wire was inserted into the blind end of the appendix under cholangioscopy. 2) Then, the cholangioscope was removed while keeping the guide wire in the appendiceal cavity. 3) Under the guidance of the guide wire, the 8.5 Fr–7 cm stent was slowly advanced along the guide wire into the lumen of the appendiceal orifice. By employing this method, the plastic stent was precisely placed within the appendiceal cavity, which could facilitate continuous expansion and drainage. The stent was usually removed via colonoscopy at 3 months after the procedure. None of the patients were treated with antibiotics except for those diagnosed with acute appendicitis following the endoscopic-assisted ERAT procedure. 

The occurrence of complications within 24 and 48 h postoperatively mainly included worsening abdominal pain, fever, vomiting, etc. After discharge, telephone follow-up was conducted every 3 months to assess the relief of abdominal pain in patients, with a minimum follow-up period of 6 months. 

The technical success rate was defined as successful intubation of the imaging catheter, including entry into the appendiceal lumen and direct visualization of the blind end of the appendix accompanied by the removal of fecal stones in the appendix cavity along with lavage, dilation, and drainage. The clinical success rate referred to the complete disappearance of preoperative clinical symptoms and normalization of inflammatory indicators (leukocytes, neutrophil percentage, etc.). The degree of abdominal pain was assessed via a visual analog scale (VAS). A score of 0 in this VAS represents no pain, and a score of 10 represents extremely severe pain. The mean procedure time was defined as the time from the beginning of intubation into the appendix to the exit of the appendix cavity after treatment. 

Statistical analysis was performed using IBM SPSS Statistics v22.0 (Social Science Statistics Package, Inc., Chicago, IL, USA). The mean ± standard deviation was used for quantitative variables, and the percentage (%) was used for qualitative variables. 

During the study period, a total of 90 patients who met the inclusion criteria were evaluated. Of these, 30 patients were excluded based on the exclusion criteria. A total of 60 patients were included. The patient selection flowchart is presented in Fig. . Among them, 26 males and 44 females were included, with an average age of 40.0 ± 16.4 (14–75) years. The average duration of the disease course was 6.1 ± 2.6 (3–15) months. All cholangioscope-assisted ERAT procedures were performed within 24 h of admission. The baseline characteristics of all included patients are summarized in Table . Ultimately, our mean follow-up time was 6.6 ± 1.4 (6–12) months. The technical success rate of cholangioscopy was 100% (60/60). There were 57 patients (95%) with a normal appendiceal opening; however, in 3 patients (5%), the opening was stuffed and edematous, with pus adhering to it, and they received additional antibiotic treatment after ERAT. The wall of the appendix was hyperemic and edematous in 52 patients (86.7%). There were 4 cases (6.7%) of appendiceal stenosis where the imaging catheter could not pass through. Ultimately, the tip of the catheter was used for dilation and successfully reached the blind end of the appendix, where the stents were placed for drainage. There were 45 cases (75%) of fecal stones and fecal residue in the appendix cavity, and 12 cases (20%) had a small amount of fecal residue, both of which could be removed by simple lavage with normal saline. However, for fecal stones with a hard texture, large diameter, and incarceration, it was necessary to remove the stones under direct vision using a net basket. To maintain continuous patency and drainage of the appendix cavity, stents were placed in 20 patients (33.3%). The procedural clinical success rate was 90% (54/60). The abdominal pain score after the procedure was 0 (VAS method) in 90% of the patients. One patient with severe pain (VAS method) experienced some relief of abdominal pain, but it did not completely resolve. The other 5 patients with mild pain (VAS score) did not experience significant relief of abdominal pain. The mean operation time was 5.4 ± 1.9 (2–10) minutes, the average length of hospital stay was 2.1 ± 0.7 (1–5) days, and the average hospitalization expenditure was 7202.9 ± 324.4 (6500–7638) RMB. None of the patients had adverse events. The procedure-related outcomes of all the patients are summarized in Table . 

Our study demonstrated that fecal stones in the appendix were the primary cause of chronic abdominal pain related to the appendix. Through cholangioscope-assisted ERAT, the vast majority of patients experienced complete relief of abdominal pain. This might be associated with incomplete obstruction of the appendix cavity by fecal stones, causing varying degrees of increased pressure within the appendix cavity. We observed that the positive rate of appendiceal fecal stones detected by cholangioscopy was lower than that of preoperative CT examination. We speculated that most of them might have been excreted with intestinal peristalsis during oral bowel preparation. The vast majority of fecal stones and fecal residue can be successfully flushed under direct visualization via cholangioscopy, and a small portion needs to be removed using a basket with the aid of cholangioscopy, which is in line with research reports related to acute appendicitis . Appendiceal stenosis is a rare cause of abdominal pain related to the appendix. Traditional X-ray-assisted ERAT is difficult to detect and cannot be effectively dilated . In this study, cholangioscope-assisted ERAT was employed to clearly visualize the location and degree of stenosis and to precisely deliver a guidewire to the distal end of the appendix. Our experience was that the tip of the cholangioscope could be utilized for stenosis dilation with the assistance of a guidewire, after which a stent could be implanted to maintain dilation and drainage . Interestingly, some patients with larger fecal stones had no significant stenosis of the appendix cavity, and we also implanted stents after cleaning them to maintain continuous patency, with a higher remission rate of abdominal pain, which might be related to the effective prevention of fecal stones from reentering by occupying the appendix cavity after stent implantation. Moreover, we discovered that, in contrast to acute appendicitis patients, the majority of patients with chronic abdominal pain related to the appendix had normal inflammatory indicators and smooth mucosa at the opening of the appendix. This might also serve as an important reason for the 100% success rate of the ERAT technique in this study. In addition to patients with common lower right abdominal pain, patients with chronic abdominal pain related to the appendix were more inclined to experience mild to moderate periumbilical pain and bloating, which could be related to abnormal intestinal dysfunction. Therefore, atypical symptoms, ambiguous imaging, and endoscopic findings make chronic abdominal pain associated with the appendix more difficult to diagnose . In recent years, cholangioscopy has been employed for the direct visualization of acute appendicitis, achieving precise treatment of mucosal congestion, edema, fecal stones, and appendiceal stenosis in the appendiceal cavity . We innovatively used cholangioscopy-assisted ERAT to treat chronic abdominal pain related to the appendix. However, three patients were diagnosed with acute appendicitis during the procedure, which was considered an acute exacerbation of chronic appendicitis, and successfully underwent ERAT, avoiding surgical intervention. A few patients experienced no significant relief of abdominal pain after ERAT, which was highly likely to be nonappendiceal chronic abdominal pain, avoiding negative appendectomy. These findings fully demonstrated the importance of cholangioscopy-assisted ERAT in the diagnosis of this condition. At present, there is a lack of randomized controlled studies on the diagnosis and treatment of chronic abdominal pain related to the appendix, and more cases are reported in series . The traditional X-ray-assisted ERAT is used for chronic abdominal pain related to the appendix through intubation and injection of contrast agent for appendiceal imaging. However, in most cases, the appendiceal imaging is poorly visualized, making it difficult to accurately assess the condition of the appendiceal cavity, and it is uncertain whether the appendiceal fecal stones have been completely cleared. Our research advantage lies in the use of cholangioscopy combined with ERAT to achieve precise diagnosis and treatment through direct visualization of the appendiceal cavity. At the same time, the cholangioscopy can be adjusted in four directions, which has a higher success rate for intubation in patients with large angles of the appendix cavity that are difficult to intubate with X-ray assistance. More importantly, it liberates both patients and doctors from the harm caused by X-rays. Compared with surgery, it is more minimally invasive, simpler to perform, quicker to recover, less costly, safer, and suitable for technology promotion . However, its limitation lies in the high price of cholangioscopy, which is a disposable tool. Our study also has certain limitations, including its retrospective design, small sample size, absence of a control group, and long-term follow-up data. In summary, cholangioscope-assisted ERAT might be an effective technique for diagnosing and treating chronic abdominal pain related to the appendix, which can, to some extent, avoid negative appendectomy. The further development of inexpensive disposable or multipurpose appendicoscopy tools will render this technology more appealing. 

