Objective. To measure the pressures of the common bile duct in patients with and without cholelithiasis and relating them to the presence of pancreatobiliary reflux.

Summary Background Data. The reflux of pancreatic enzymes into the epithelium of the bile duct and mainly of the gallbladder is an abnormal phenomenon that plays a role in the lithogenesis and carcinogenesis of this epithelium. It has been suggested that the cause of this reflux is the dysfunction of the sphincter of Oddi. Because the pressure of the common bile duct depends on the pressures of the sphincter of Oddi, this dysfunction would be reflected in an increase in the pressure of the common bile duct in patients with cholelithiasis.

Methods. A prospective case-control study was designed. The universe was constituted by a convenience sample in which all patients undergoing gastrectomy for gastric cancer during 30 months in our institution were included. The primary outcome measure was to establish differences between common bile duct pressures in patients with and without cholelithiasis.

Results. Common bile duct pressures in patients with gallstones showed a significant elevation (Mean 16.9 mmHg) compared to those of patients without gallstones (Mean 3.3 mm Hg) (p<0.0001). These pressures correlated with the values of amylase and lipase in gallbladder bile; higher levels of these enzymes were found in patients with gallstones compared to patients without gallstones (p<0.0001).

Conclusions. Common bile duct pressures in patients with cholelithiasis were significantly elevated above the parameters previously considered normal.

A prospective study of cases and controls was designed using a previously validated model for the study of occult pancreatobiliary reflux in patients undergoing gastrectomy for gastric cancer, in which cholecystectomy is routine according to the oncological surgery protocol for gastric cancer of our institution. The study universe was constituted by a convenience sample in which all patients undergoing gastrectomy for gastric cancer during the period between January 2015 and June 2017 the investigators included. All patients included in this study signed a detailed informed consent regarding the interventions to be performed and the objectives of the study.

Cholecystectomy was performed in all patients after the section of the duodenum. Before the manipulation and dissection of the Calot triangle, a sample of 5 to 10 cc of bile was taken directly from the gallbladder. The sample was stored in a sterile tube at room temperature and immediately sent for processing. The technicians of our institutional laboratory that processed the sample did not know the details of the study. The cholecystectomy was then carried out until the cystic was reached and was cut as proximally as possible to the gallbladder. Through the cystic duct, a 4 French feeding tube equivalent to 1.35 mm in diameter (Well Lead®, Hamburg, Germany) was introduced until reaching a distance of 3 cm distal to the junction of the cystic duct and the common bile duct. Once tested for patency, this probe was connected to a standard pressure transducer used to measure intra-arterial pressure (Edwards Lifesciences™, Irvine, California, USA) and this was connected to a B40 monitor (General Electric® Medical Systems, Milwaukee, WI, USA) with the ability, among other functions, to perform pressure measurements in millimeters of mercury. The level of the junction of the cystic duct and the common bile duct was taken as a zero point, as previously described. Once the whole system was irrigated with 0.9% physiological solution and the zero point was established on the monitor with the system closed, the system was opened and pressures were measured. The minimum, maximum and mean pressures were recorded for one minute. After the procedure was completed, the gastrectomy was performed.

• PATIENTS WITH CHOLELITHIASIS
  COMMON BILE DUCT PRESSURES WERE MEASURED IN PATIENTS WITH CHOLELITHIASIS
  Intervention: Diagnostic Test: MEASUREMENT OF COMMON BILE DUCT PRESSURES
• PATIENTS WITHOUT CHOLELITHIASIS
  COMMON BILE DUCT PRESSURES WERE MEASURED IN PATIENTS WITHOUT CHOLELITHIASIS
  Intervention: Diagnostic Test: MEASUREMENT OF COMMON BILE DUCT PRESSURES

Inclusion Criteria:

• All patients with normal values of amylase, lipase, and liver function tests measured 24 hours before the intervention

Exclusion Criteria:

• Patients previously cholecystectomized
• Patients with clinical, radiological and laboratory evidence of common bile duct stones