Determine differences between lithogenic and non-lithogenic bile composition.

Gallstones constitute an entity known from antiquity, which have been found even in Egyptian mummies. In elder Greece, Tralliano discovered that gallstones are formed in the liver. Vesalio and Falopio described gallstones inside de gallbladder after a human body dissection and in 1882 Langenbuch performed the first cholecystectomy with good results, becoming the gold standard technique for cholelithiasis.

Nowadays, this pathology represents a public health problem in developed countries due to its high prevalence, which is getting higher, estimated between a 10 and a 15% of the population.

However, gallstones are asymptomatic in the 80% of the cases. In 5 years, a 10-20% of these patients will become symptomatic. The global risk of generating symptoms is about a 2% per year, meanwhile biliary tract complications in asymptomatic patients represent a 0'3% per year.

There are two main types of gallstones. The most common of them (70%) are cholesterol stones, composed of >50% of cholesterol. The other 30% are black pigment stones, with less than 20% of cholesterol in their composition.

The common ways on gallstone formation are: cholesterol supersaturation (due to a liver oversecretion); defects on gallbladder absorption, secretion and motility mechanisms; and higher percentage of deoxycholic acid in the biliary acids due to a slower intestinal movement. All of that leads to supersaturation and cholesterol nucleation.

Black pigment stones are formed of calcium bilirrubinate. The formation mechanism is not clearly defined, but there is an increment in not conjugated bilirubin levels, which is less soluble in water. These gallstones are more frequent in patients who show higher levels of this bilirubin, such as those with hemolysis, Gilbert syndrome or hereditary spherocytosis. They are also common in patients with Crohn disease (specially in those with ileal resection) and cystic fibrosis, in which exists an enterohepatic circulation alteration, driving to an increase on biliary salts and non-conjugated bilirubin levels.

Our work hypothesis is that bile composition in patients with gallstones on the gallbladder is different from those who doesn't show lithiasis.

Inclusion Criteria for the Study Group:

1. Patients included for an elective cholecystectomy.
2. Normal hepatic and renal function.
3. Able to understand the nature of the study.
4. Wish to participate in the study and sign the informed consent.

Inclusion Criteria for the Control Group:

1. Patients included for an hepatectomy with gallbladder exeresis for surgery reasons, without lithiasis.
2. Patients included for peritoneal carcinomatosis surgery with gallbladder exeresis for surgery reasons, without lithiasis.
3. Organ donors.
4. Normal hepatic and renal function.
5. Able to understand the nature of the study.
6. Wish to participate in the study and sign the informed consent.

Exclusion Criteria:

1. Under 16 years old
2. Hepatic or renal insufficiency
3. Impossibility to understand the aim of the study

It includes patients who suffer from gallstones, which are operated for that reason (open or laparoscopic cholecystectomy), and patients who go through the same intervention for other reasons (cancer, organ donation)