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 [9]. 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 [10]. 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 [11]. 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 [12, 13]. 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 [14, 15]. 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 [16, 17]. 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 [18, 19]. 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.