**Abstract**

There is an epidemic of nonalcoholic fatty liver disease (NAFLD) paralleling the epidemic of obesity and metabolic syndrome. NAFLD is the most common cause of abnormal liver function test and chronic liver disease in the Western world. NAFLD can progress to nonalcoholic steatohepatitis, cirrhosis of the liver, and hepatocellular carcinoma. Most patients with NAFLD die from cardiovascular disease and malignancy. Medical therapy for NAFLD is not very effective at the present time. Treatment of NAFLD starts with weight loss. Bariatric surgery is able to cause significant and sustained weight loss. There are different models of bariatric surgery. Commonly performed ones are Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, and laparoscopic adjustable gastric banding (LAGB). They can improve steatosis, steatohepatitis, and fibrosis in non-cirrhotic and compensated cirrhotic patients. Each of them has benefits and risks. The bariatric surgical procedures need to be individualized according to the patient's condition.

**Keywords:** nonalcoholic fatty liver disease, bariatric surgery, role of surgery in NAFLD, liver transplantation and NAFLD

#### **1. Introduction**

There is a tremendous rise in the prevalence of nonalcoholic fatty liver disease (NAFLD) throughout the world [1]. About 20% of the world population suffer from NAFLD [2]. NAFLD is the most common cause of chronic liver disease in the developed countries. In the United States, it is the second most common indication of liver transplantation. It affects all age groups and ethnicities [3]. The epidemic of NAFLD parallels the epidemic of obesity and metabolic syndrome in the world. In fact, most (80%) of the patients suffering from NAFLD are overweight [4], and 85% of morbidly obese individuals with body mass index (BMI) >40 have NAFLD [5]. As the disease is related to insulin resistance, 70% of non-insulin-dependent diabetic patients suffer from NAFLD [6]. The disease starts with benign reversible macrovesicular steatosis affecting more than 5% of the hepatocytes. Then it progresses to nonalcoholic steatohepatitis (NASH), steatofibrosis, cirrhosis of the liver, liver failure, and hepatocellular carcinoma [7]. Weight loss, pharmacological intervention, and bariatric surgery are the three main modes of therapy of NAFLD. Weight loss by diet, exercise, and lifestyle modification is the first-line treatment of NAFLD. There are few pharmacologic agents available for the treatment of NAFLD. But as it is difficult to lose weight and maintain targeted body weight by lifestyle modifications, and pharmacological interventions are not

that successful, there is a potential role of bariatric surgery in the treatment of NAFLD. In this chapter, we will be discussing the indications and types of bariatric surgery as well as their benefits and risks.

At the present time, bariatric surgery is indicated only for morbidly obese individuals. The American Society for Metabolic and Bariatric Surgery (ASMBS) recommends bariatric surgery for individuals who have BMI of ≥40 or ≥35 plus at least one or more obesity-related complications (type II diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea, nonalcoholic fatty liver disease, gastrointestinal disorders, osteoarthritis, heart disease) and have failed to achieve targeted weight loss despite diet and exercise [8]. The American Association for the Study of Liver Diseases (AASLD) recommends to consider bariatric surgery in otherwise obese individuals with NALFD or NASH.

Bariatric surgery is able to achieve severe (40–71%) weight loss and improve insulin resistance and obesity-related metabolic complications [9]. There are many studies showing the benefits of weight loss in NAFLD following bariatric surgery. But at the present time, there is no large randomized control trial evaluating the effects of bariatric surgery in NAFLD.

Bariatric surgical procedures are classified into three broad categories on the basis of their mechanism of action [10]:

1.Restrictive procedures: The size of the stomach is surgically reduced, and as a result, the food intake is diminished. These procedures include sleeve gastrectomy, laparoscopic adjustable gastric banding (LAGB), and vertical band gastroplasty (not done anymore because of high complication rate and difficulty in maintaining weight loss). In sleeve gastrectomy (**Figure 1**), the gastric fundus and greater curvature of the stomach are resected vertically (>80% of the stomach is removed) making the stomach tubular (like a banana) with less capacity (initial filling volume of <100 ml) and less stretchy with rapid gastric emptying. Feeling of hunger is reduced because of resection of fundus containing ghrelinergic cells [11]. In LAGB (**Figure 2**), an adjustable and inflatable silicone band is placed around the upper stomach dividing the stomach into two compartments: a proximal small gastric pouch (20–30 ml volume) and

**61**

**Figure 3.**

*BPD with duodenal switch.*

*Non-alcoholic Fatty Liver Disease and Surgery DOI: http://dx.doi.org/10.5772/intechopen.86146*

subcutaneous infusion port [12].

diversion (**Figure 4**).

**Figure 2.** *LAGB.*

> a distal larger residual stomach. The size of the opening between the gastric pouch and the residual stomach can be adjusted as the band is connected to a

2.Malabsorptive procedures: A long segment of the small intestine is bypassed, and as a result, the digestive juices digest the food in the distal part of the small intestine, and malabsorption of food occurs. These procedures include biliopancreatic diversion with duodenal switch (**Figure 3**) and biliopancreatic

In biliopancreatic diversion (BPD) with duodenal switch (DS), the stomach size is first reduced by doing a partial sleeve gastrectomy and preserving the pylorus. Then the first part of the duodenum is divided distal to the pylorus. The distal

**Figure 1.** *Sleeve gastrectomy.*

*Non-alcoholic Fatty Liver Disease and Surgery DOI: http://dx.doi.org/10.5772/intechopen.86146*

#### **Figure 2.** *LAGB.*

*Liver Disease and Surgery*

surgery as well as their benefits and risks.

effects of bariatric surgery in NAFLD.

basis of their mechanism of action [10]:

otherwise obese individuals with NALFD or NASH.

that successful, there is a potential role of bariatric surgery in the treatment of NAFLD. In this chapter, we will be discussing the indications and types of bariatric

At the present time, bariatric surgery is indicated only for morbidly obese individuals. The American Society for Metabolic and Bariatric Surgery (ASMBS) recommends bariatric surgery for individuals who have BMI of ≥40 or ≥35 plus at least one or more obesity-related complications (type II diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea, nonalcoholic fatty liver disease, gastrointestinal disorders, osteoarthritis, heart disease) and have failed to achieve targeted weight loss despite diet and exercise [8]. The American Association for the Study of Liver Diseases (AASLD) recommends to consider bariatric surgery in

Bariatric surgery is able to achieve severe (40–71%) weight loss and improve insulin resistance and obesity-related metabolic complications [9]. There are many studies showing the benefits of weight loss in NAFLD following bariatric surgery. But at the present time, there is no large randomized control trial evaluating the

Bariatric surgical procedures are classified into three broad categories on the

1.Restrictive procedures: The size of the stomach is surgically reduced, and as a result, the food intake is diminished. These procedures include sleeve gastrectomy, laparoscopic adjustable gastric banding (LAGB), and vertical band gastroplasty (not done anymore because of high complication rate and difficulty in maintaining weight loss). In sleeve gastrectomy (**Figure 1**), the gastric fundus and greater curvature of the stomach are resected vertically (>80% of the stomach is removed) making the stomach tubular (like a banana) with less capacity (initial filling volume of <100 ml) and less stretchy with rapid gastric emptying. Feeling of hunger is reduced because of resection of fundus containing ghrelinergic cells [11]. In LAGB (**Figure 2**), an adjustable and inflatable silicone band is placed around the upper stomach dividing the stomach into two compartments: a proximal small gastric pouch (20–30 ml volume) and

**60**

**Figure 1.** *Sleeve gastrectomy.* a distal larger residual stomach. The size of the opening between the gastric pouch and the residual stomach can be adjusted as the band is connected to a subcutaneous infusion port [12].

2.Malabsorptive procedures: A long segment of the small intestine is bypassed, and as a result, the digestive juices digest the food in the distal part of the small intestine, and malabsorption of food occurs. These procedures include biliopancreatic diversion with duodenal switch (**Figure 3**) and biliopancreatic diversion (**Figure 4**).

In biliopancreatic diversion (BPD) with duodenal switch (DS), the stomach size is first reduced by doing a partial sleeve gastrectomy and preserving the pylorus. Then the first part of the duodenum is divided distal to the pylorus. The distal

**Figure 3.** *BPD with duodenal switch.*

**Figure 4.** *Biliopancreatic diversion (BPD).*

end of the duodenum is closed. The jejunum is then divided 250 cm proximal to the ileocecal valve. The distal end of the jejunum is then anastomosed to the proximal end of the duodenum creating a duodenojejunostomy (duodenal switch). The proximal end of the jejunum is then attached to the ileum 100 cm proximal to the ileocecal valve. As a result, there is restriction of food intake due to gastric sleeve, and most of the small intestine is bypassed leading to malabsorption of nutrients. The biliary pancreatic limb carries biliary and pancreatic secretions into the distal part of the ileum (biliary pancreatic diversion).

In biliopancreatic diversion (BPD), the lower and middle third of the stomach is resected leaving a small gastric pouch. The upper end of the duodenum is closed. The distal jejunum is divided. The distal end of the jejunum is then anastomosed to the gastric pouch. The proximal end of the jejunum is then anastomosed to the distal ileum forming a short common channel in which biliary and pancreatic juices mix with food prior to proceeding into the colon [13].

3.Hybrid procedures: There is combination of restriction of food intake and malabsorption of food. The typical example is Roux-en-Y gastric bypass (RYGB). This procedure divides the upper part of the stomach to create a small gastric pouch with a capacity of 20–30 ml (**Figure 5**). The proximal jejunum is divided 50 cm beyond the ligament of Treitz. The distal jejunal end is then connected to the gastric pouch. The proximal jejunal end of the small bowel is sutured to the jejunum (75–150 cm from the gastric pouch) to form the so-called Roux-en-Y reconstruction. The small gastric pouch (restrictive component) causes early satiety and helps in decreasing food intake. The Roux or alimentary limb (typically 75–150 cm long) extends from the gastric pouch to the

**63**

**Figure 5.** *RYGB.*

*Non-alcoholic Fatty Liver Disease and Surgery DOI: http://dx.doi.org/10.5772/intechopen.86146*

> jejunojejunostomy site and carries ingested food. The proximal biliopancreatic limb (30–60 cm long) containing excluded stomach, duodenum, and proximal jejunum transfers biliary and pancreatic secretions to the jejunojejunostomy site. Most of the digestion and absorption occur in the common channel which

Sleeve gastrectomy: Different studies were done to find out the effect of sleeve gastrectomy on NAFLD. Algooneh et al. observed that 56% of total 84 transabdominal ultrasonographically diagnosed NAFLD patients showed complete resolution of hepatic steatosis 3.3 years (average) after isolated sleeve gastrectomy [14]. Karcz et al. found that there was significant reduction (>50%) of transaminases in NASH patients within 6 months of isolated sleeve gastrectomy [15]. Parveen-Raj et al. did a prospective observational trial and found that surgically induced weight loss improved NAFLD histology significantly 6 months after isolated sleeve gastrectomy

LAGB: There have been several studies showing the effects of LAGB on NAFLD. Most of the studies reported improvement of hepatic steatosis, steatohepa-

Few LAGB studies with their effects on NAFLD are mentioned in **Table 1**. Biliopancreatic diversion (BPD) and biliopancreatic diversion with duodenal switch (BPD with DS): Both procedures produce long-term malabsorption and severe weight loss. They are not widely done. Their effects on NAFLD are summa-

In patients with BPD with DS, the transient deterioration of transaminases and steatohepatitis seen in the first 6 months postoperatively was possibly due to rapid weight loss. Transaminases became normalized by 12 months. Then there

titis, and fibrosis, but some studies showed mild increase in fibrosis.

extends from the jejunojejunostomy site to the ileocecal valve.

**2. Benefits and risks of bariatric surgery on NAFLD**

in morbidly obese patients [16].

rized in two studies in **Table 2**.

A schematic diagram of different bariatric surgeries is shown below.

*Non-alcoholic Fatty Liver Disease and Surgery DOI: http://dx.doi.org/10.5772/intechopen.86146*

#### **Figure 5.** *RYGB.*

*Liver Disease and Surgery*

end of the duodenum is closed. The jejunum is then divided 250 cm proximal to the ileocecal valve. The distal end of the jejunum is then anastomosed to the proximal end of the duodenum creating a duodenojejunostomy (duodenal switch). The proximal end of the jejunum is then attached to the ileum 100 cm proximal to the ileocecal valve. As a result, there is restriction of food intake due to gastric sleeve, and most of the small intestine is bypassed leading to malabsorption of nutrients. The biliary pancreatic limb carries biliary and pancreatic secretions into the distal part of the ileum (biliary pancreatic diversion).

In biliopancreatic diversion (BPD), the lower and middle third of the stomach is resected leaving a small gastric pouch. The upper end of the duodenum is closed. The distal jejunum is divided. The distal end of the jejunum is then anastomosed to the gastric pouch. The proximal end of the jejunum is then anastomosed to the distal ileum forming a short common channel in which biliary and pancreatic

3.Hybrid procedures: There is combination of restriction of food intake and malabsorption of food. The typical example is Roux-en-Y gastric bypass (RYGB). This procedure divides the upper part of the stomach to create a small gastric pouch with a capacity of 20–30 ml (**Figure 5**). The proximal jejunum is divided 50 cm beyond the ligament of Treitz. The distal jejunal end is then connected to the gastric pouch. The proximal jejunal end of the small bowel is sutured to the jejunum (75–150 cm from the gastric pouch) to form the so-called Roux-en-Y reconstruction. The small gastric pouch (restrictive component) causes early satiety and helps in decreasing food intake. The Roux or alimentary limb (typically 75–150 cm long) extends from the gastric pouch to the

juices mix with food prior to proceeding into the colon [13].

**62**

**Figure 4.**

*Biliopancreatic diversion (BPD).*

jejunojejunostomy site and carries ingested food. The proximal biliopancreatic limb (30–60 cm long) containing excluded stomach, duodenum, and proximal jejunum transfers biliary and pancreatic secretions to the jejunojejunostomy site. Most of the digestion and absorption occur in the common channel which extends from the jejunojejunostomy site to the ileocecal valve.

A schematic diagram of different bariatric surgeries is shown below.
