Influence of Roux-en-Y Gastric Bypass on the Hepatocellular Function and Bile Flow of Obese Patients Assessed by Scintigraphy with DISIDA.

Background: Obesity is associated with nonalcoholic fatty liver disease (NAFLD), which is improved by bariatric surgery. Hepatobiliary scintigraphy with 99m.-Tc diisopropylacetanilido iminodiacetic acid (99mTc-DISIDA) has proved to be highly effective for the assessment of bile flow, representing an indirect measurement of hepatocyte and cholangiocyte function. The objective of this study was to assess the effects of Roux-en-Y gastric bypass (RYGB) on bile flow in obese subjects by hepatobiliary scintigraphy. This study was conducted in a public university hospital in Brazil.

Methods: Twenty obese patients and five nonobese patients (with no hepatic or biliary disease) were studied. The obese patients were submitted to anthropometric evaluation and biochemical exams when they arrived at the service, during the immediate preoperative period and 3, 6, and 12 months after surgery. They were also submitted to abdominal ultrasound and hepatobiliary scintigraphy with 99mTc-DISIDA during the preoperative period and 12 months after RYGB. Tmax (time of maximum marker uptake) and T1/2 (half time between peak uptake and disappearance of the marker) were determined and compared between obese patients and controls, before and after surgery. The results were compared to those obtained with an intraoperative liver biopsy.

Results: A weight loss of 12.2 ± 4.3 % was observed during preparation for surgery, and a loss of 30.4 ± 5.6 % was observed 1 year after RYGB. Ultrasound hepatic analysis revealed some degree of NAFLD in the operated patients. Obese patients showed a prolonged T1/2 compared to control, with a reduction to normal levels after RYGB.

Conclusions: We concluded that NAFLD compromises bile excretion, a process that can be reversed by treatment with RYGB.