Sonographic Evaluation of Visceral Fat After Bariatric Surgery

Excess visceral fat is a key factor in the development of metabolic syndrome associated with obesity. After bariatric surgery, patients experience weight loss accompanied by a decrease in the amount of total body fat. It is unclear how the different surgical procedures vary in their effect on the visceral and subcutaneous fat change. Ultrasonography (US) is an effective, efficient method in assessing this metabolically active layer of fat even when compared with gold standard techniques such as computed tomography and magnetic resonance imaging. Only a few studies managed to show the actual decrease in the visceral fat layer after these kinds of surgeries. The aim is to compare by ultrasound evaluation the extent of fat layers reduction after laparoscopic adjustable gastric banding (LAGB), laparoscopic sleeve gastrectomy (LSG) and laparoscopic roux-en-y gastric bypass (LRYGB). The hypothesis is that the sleeve gastrectomy and gastric bypass being not only a restrictive procedure but also a malabsorptive procedure will have the best results in decreasing the amount of visceral fat.

excess visceral fat is a key factor in the development of metabolic syndrome associated with obesity. After bariatric surgery, patients experience weight loss accompanied by a decrease in the amount of total body fat. It is unclear how the different surgical procedures vary in their effect in reducing the amount of the visceral fat layer . Ultrasonography (US) is an effective, efficient method in assessing this metabolically active layer of fat even when compared with gold standard techniques such as computed tomography and magnetic resonance imaging. Only a few studies managed to show the actual decrease in the visceral fat layer after these kinds of bariatric surgeries. The aim is to compare by ultrasound evaluation the extent of fat layers reduction after laparoscopic adjustable gastric banding (LAGB), laparoscopic sleeve gastrectomy (LSG) and laparoscopic roux-en-y gastric bypass (LRYGB).

Visceral fat (VF) will be defined as the depth, in centimeters, from the rectus abdominis muscle to the aorta; and subcutaneous fat (SCF) defined as the depth, in centimeters, from the skin to the rectus abdominis muscle. Results will be compared with anthropometric measures as weight and waist circumference as well as laboratory results to try and find correlation between sonographic improvement and anthropometric and laboratory improvement.

The hypothesis is that the sleeve gastrectomy and gastric bypass being not only a restrictive procedure but also a malabsorptive procedure will have the best results in decreasing the amount of visceral fat.

Morbid obese patients admitted electively to our surgery ward after receiving detailed explanation about each type of surgery and after independently choosing to undergo either a laparoscopic adjustable gastric banding, a sleeve gastrectomy or a gatsric bypass will be offered to participate in the study.

The patients must meet criteria for being morbid obese as defined as a body mass index greater than 40 kg/meter*meter or a body mass index greater than 35 with relevant comorbidities. The patients must meet other inclusion and exclusion criteria as defined below.

The patients will be offered to participate in the study regardless of their gender or race.

• patients undergoing laparoscopic adjustable gastric banding
  morbid obese patients undergoing laparoscopic adjustable gastric banding will be evaluated by ultrasound before surgery and one year after surgery to determine the amount of visceral fat layer decreased.
• patients undergoing laparoscopic sleeve gastrectomy
  morbid obese patients undergoing laparoscopic sleeve gastrectomy will be evaluated by ultrasound before surgery and one year after surgery to determine the amount of visceral fat layer decreased
• patients undergoing laparoscopic gastric bypass
  morbid obese patients undergoing laparoscopic gastric bypass will be evaluated by ultrasound before surgery and one year after surgery to determine the amount of visceral fat layer decreased

Inclusion Criteria:

• age above 18 years and below 70 years
• patients considered to suffer from morbid obesity as defined as a body mass index above 40 kg/meter*meter or above 35 kg/meter*meter with comorbidities relevant to obesity such as : diabetes, hypertension, arthralgia, obstructive sleep apnea and hyperlipidemia and eligible for surgery
• patients that electively and independently chose to undergo a bariatric surgery in our surgery ward.
• patients expressing their desire to participate in the study and after signing informed consent.
• patients that underwent a lecture about the pros and cons of the different types of bariatric surgery performed in our surgery ward:laparoscopic adjustable gastric banding, a sleeve gastrectomy or a gastric bypass and chose independently the type of surgery they want to undergo.
• patients that tried to lose weight in conventional ways such as physical activity and diets with no success.

Exclusion Criteria:

• patients under the age of 18 or above the age 70.
• patients unable to read, understand, comprehend and sign the informed consent form.
• patients not meeting the criteria for the definition morbid obesity as defined as a body mass index above 40 kg/meter*meter or above 35 kg/meter*meter with comorbidities relevant to obesity such as : diabetes, hypertension, arthralgia, obstructive sleep apnea and hyperlipidemia.
• pregnant patients.
• patients addicted to alcohol or other recreational drugs.
• patients suffering from a malignant comorbidity.
• patients suffering for a morbid obesity state because of a endocrine problem such as hypothyroidism or cushing disease.