Since the first report of LC was published in Japan in 1990 [16], the strategy and techniques of the procedure have been well established, ensuring its safe execution. This is often regarded as the initial step in the surgical training of young surgeons and trainees. Therefore, careful attention must be paid to the intraoperative and postoperative complications associated with LC. Our findings suggest that surgeons should reconsider the method of CD closure when MRCP results indicate CD enlargement. Incomplete CD closure may lead to postoperative bile leakage and intra-abdominal abscess formation [15], requiring the surgeon to consider alternative techniques such as using an LS or larger clips. In recent years, LC has been performed by young surgeons as an introductory procedure at various institutions [17]. However, inflammation and adhesion around the gallbladder can increase procedural difficulty. In this study, preoperative MRCP imaging results were found to predict the difficulty of CD closure, and this information could help prevent unexpected intraoperative complications.

In general, acute or chronic cholecystitis could complicate intraoperative procedures. Several difficulty scoring systems have indicated that factors such as cholecystitis, cholangitis, preoperative ERCP findings, and gallbladder wall thickness contribute to the complexity of LC [4-7]. According to the 2018 Tokyo Guidelines, diffuse scarring in the Calot’s triangle area and around the gallbladder increases the difficulty of intraoperative procedures [2]. Although many scoring systems define the level of difficulty based on operative time, perioperative complications, and conversion to open abdominal surgery [4-7], there are few reports addressing the impact of the CD closure method. Our results indicate that the presence of acute cholecystitis does not affect CD closure; however, both blood loss and operative time were significantly increased (Table 3). Consistent with these findings, blood loss was significantly higher in the unusual group (Table 1). This can be attributed to the well-developed peri-bile duct vascularization [18], where CD dilation may lead to increased vascularity in the surrounding area. Even if no evidence of cholecystitis is found before surgery, surgeons should anticipate the possibility of oozing around the CD in cases of an enlarged CD.

We believe that in patients with a dilated CD detected before surgery, the gallstones may either pass through the CD or become impacted within it. Our findings indicate that anatomical variations of the CD may be one of the risk factors that necessitate the use of an unusual closure method (Table 2). Few studies have investigated the correlation between CD anatomical variations and the occurrence of GBS. Park et al. classified CD anatomical variations into types I to IV and reported that these differences contributed to the incidence of gallstones [14]. They noted that bile stasis and increased bile viscosity are more likely to occur in cases with a long CD, which subsequently contributes to the development of gallstones. Moreover, some reports suggest that a long CD may contribute to the development of secondary or residual stones after LC [19]. It remains controversial whether the residual CD length is a risk factor for the incidence of gallstones after LC, as further research is needed to determine the optimal dissection point for patients with a long CD.

We have defined the unusual CD closure methods to include the use of 10 mm clips or other techniques. The term “10 mm” refers to the diameter of the device shaft and is not indicative of the size or length of the clip itself. This distinction is important because 10 mm clips require a larger trocar (10-12 mm epigastric trocar) compared with 5 mm clips. Trocar site hernia (TSH) is a rare complication following LC, occurring in fewer than 1% of cases [20]. However, it is most often observed at sites where a 10 mm trocar was used [20]. Undoubtedly, trocar size is not the only risk factor for TSH; other factors, such as obesity and sex, have also been linked to this complication. Based on these findings, we believe that the routine use of a 10-12 mm epigastric trocar for LC is not recommended.

There are several limitations to our study. First, it is a retrospective analysis conducted at a single institution. As such, the decision to use an unusual CD closure method during surgery was made by the surgeons based on their clinical judgment. Second, we excluded patients who did not undergo MRCP before surgery, which may have resulted in a different cutoff value for CD size based on MRCP findings. Moreover, we assessed the length of the CD using MRCP images, which primarily represent the intraluminal capacity of the CD. MRCP primarily employs T2-weighted MRI pulse sequences, which produce high-intensity signals for fluids within the biliary and pancreatic ducts [21]. Consequently, the true CD diameter value may differ between those obtained via MRCP images and through intraoperative findings. We found that a CD diameter greater than 4.22 mm necessitated the use of 10 mm clips or an LS. However, some patients with a CD diameter below this threshold may still require 10 mm clips or alternative devices due to localized CD enlargement. Finally, we did not assess which device is the most effective among the unconventional closure methods. Our results showed that the use of suturing, a ligature device, and 10 mm clips was more common than an LS. Several researchers have reported the efficiency and safety of LS [12,13]. However, Thomas et al. noted that the use of LS may be associated with postoperative complications of Clavien-Dindo grade ≥3 [15]. Further, the comparison between 10 mm clips and LS has not been thoroughly investigated, leaving the question of which device is most effective unresolved. Further research is needed to clarify this issue.