Non-Alcoholic Fatty Liver is a common clinical and histological condition associated with metabolic syndrome in patients with and without excess body weight. It represents the most common cause of liver disease in the western world and it is characterized by an excess accumulation of fatty vacuole within hepatocytes.

Patients with non-alcoholic fatty liver disease (NAFLD) can progress to non-alcoholic steatohepatitis (NASH), and then into cirrhosis and its complications.

The prevalence of hepatic steatosis goes from 16 to 31% in the general population, from 50 to 80% in the obese population and up to 96% in morbidly obese patients. As the majority of obese individuals have NAFLD, non-invasive and widely applicable screening tools for the assessment of liver fibrosis and steatosis are needed. The detection in early stages is the main predictive factor of the long-term outcome.

Liver biopsy has traditionally been the gold standard for the assessment of patients with NAFLD, although the well-known limitations. Among the non-invasive tools available in the market, the FibroScan® (Echosens™, Paris, France) has been shown to be a useful tool for diagnosing fibrosis and steatosis in patients with suspected NAFLD. The FibroScan® is an ultrasound-based vibration-controlled transient elastography (VCTE™) device dedicated to liver stiffness measurement (LSM) and the controlled attenuation parameter (CAP).

Several clinical studies have shown the benefit of measuring hepatic stiffness with the FibroScan® in overweight/moderately obese persons. The ability to identify significant fibrosis and cirrhosis has been demonstrated in normal and overweight patients affected with chronic hepatitis B and C, biliary diseases, alcohol related liver disease and NAFLD.

However, subcutaneous fat attenuates the transmission of shear waves into the liver and the ultrasonic signals used to measure their speed of propagation. When scanning morbidly obese patients (BMI≥35 kg/m²) with the XL+ probe, unreliable results occur mainly due to obesity. Therefore, the XL probe has been enabled to expand the applicability of the FibroScan® but, the realization of the XL+ examination is still very difficult in the case of morbidly obese patients. This is why to reduce this failure rate, Echosens has worked on developing the XXL probe specifically for measuring the LSM in morbidly obese patients.

Inclusion Criteria:

• Patient must be at least 18 years old
• Patient must be able to give written informed consent
• Patient affiliated to a social security system
• Patients participating in the standard bariatric surgery care program (bariatric surgery criteria defined with BMI ≥ 40 kg / m² or patients with BMI ≥ 35 kg / m² and at least 1 associated co-morbidity

Exclusion Criteria:

• Patient with presence of ascites
• Patients with exclusion criteria for bariatric surgery