The risk of a CBD stone is classically defined by a combination of clinical, biological and radiological parameters [4]. The present study assessed patients without previous CBD exploration and confirmed the value of LFTs, and clinical variables such as fever, as well as signs of cholecystitis on US [12]. In addition, women were more likely to present a stone.

Despite these known risk factors, our local policy is to perform an IOC in all patients undergoing cholecystectomy because models predicting the presence of a stone are not accurate enough [10–12]. Alternatively, IOC appears as efficient as ERCP in predicting the presence of a stone [13, 14]. Additionally, it bears a didactic value, training younger surgeons at approaching the CBD for a potential exploration. Finally, IOC also helps to detect an iatrogenic bile duct lesion [15]. We acknowledge, however, that patients with normal LFTs undergoing elective cholecystectomy do not necessarily need an IOC. Conversely, we strongly recommend following the IOC path in patients undergoing cholecystectomy for acute gallstone-related diseases, especially in the case of abnormal LFTs.

Overall, an intra-operative stone was suspected in 12.5% (50/399) of the studied patients, based on IOC abnormalities. The preliminary injection of a limited quantity of contrast agent helps to detect a filling defect, while a stone can be less visible after the injection of a large volume of contrast agent. Of note, manoeuvres such as changing the table position and/or injecting saline help in the differential diagnosis with an air bubble. The second type of abnormality is the lack or a difficult contrast passage into the duodenum, which may be due to a trapped CBD stone, an Oddi’s sphincter spasm, or a lesion of the sphincter (neoplasia/inflammation).

Only half of the suspected stones could be confirmed post-operatively. Based on the current data, it remains difficult to predict which patients will finally present a confirmed stone. Post-operative LFTs have no predictive power. LFTs may remain increased because of the previous injection of contrast during IOC or because a liver lesion occurred during the removal of the gallbladder from its bed. Only the presence of a filling defect tends to be predictive of a remaining CBD stone, whereas the absence of contrast passage into the duodenum is not. Most contrast passage alterations are likely linked to spasms. The net results of these observations are that a post-operative CBD assessment is required in all patients with an IOC abnormality and that LFTs do not necessarily need to be repeated after surgery due to their low predictive value.

We favour the use of post-operative EUS (+/-ERCP) in patients with an image of a stone during same-stay cholecystectomy. In fact, EUS accuracy is very high (near 97%) as are the sensitivity (71–100%), specificity (67–100%) and the positive or negative predictive values [16–19].

Such a strategy allowed the extraction of all stones by ERCP (with the exception of one patient treated by interventional radiology). As an alternative, laparoscopic CBD exploration could also be used. However, it can require the use of laparoscopic choledochotomy, with a risk of bile leak up to 15%, especially in patients with non-dilated CBD, and in the presence of inflammation [20]. In addition, the ERCP stone clearance rate appears higher than that after laparoscopic bile duct exploration [21, 22].

Another option would have been to perform ERCP during surgery (with or without rendezvous) [23]. Here again, we have not selected this strategy primarily because half of the patients do not show a confirmed stone on post-operative tests (and would have undergone unnecessary ERCP). Secondarily, emergency intra-operative ERCP is difficult to organize because of endoscopist availability and the positioning of the patient being non-standard for ERCP. The present study is limited by its retrospective nature and its potential for type 2 errors. However, it provides a real-life assessment of the proposed management strategy of patients at risk of CBD stones.

The present study is limited by its retrospective nature and its potential for type 2 errors. However, it provides a real-life assessment of the proposed management strategy of patients at risk of CBD stones.