Surgical and Endoscopic Treatment of Obesity

Gastric Bypass

After gastric bypass, both restrictive and hormonal mechanisms limit food intake and nutrient absorption. First performed by Mason and Ito in 1966, gastric bypass has since been modified twice: once in 1967 to incorporate a Roux limb rather than a loop gastrojejunostomy, and again in 1994 to be a primarily laparoscopic procedure.

The laparoscopic approach is superior to the open approach and has considerably lower complication rates. Laparoscopic gastric bypass has reduced mortality rates and lowered rates of wound infection, pulmonary and thromboembolic complications, and incisional hernias, and has decreased the average hospitalization time to about 2 days. There are many variations of laparoscopic RYGB techniques, but essential components include construction of a gastric pouch, attaching the pouch to the jejunum, and re-routing digestive enzymes such that they do not contact food until it reaches the jejunojejunostomy ( Fig. 8.1 A ).

At the time of surgery, care is taken to position the patient appropriately so as to facilitate intubation and prevent nerve compression and skin breakdown. To prevent postoperative nausea and vomiting, several strategies are employed, including IV hydration and small doses of glucocorticoid and ondansetron. An orogastric tube is placed to prevent gastric distension or aspiration. Prophylactic subcutaneous heparin (5000 units), sequential compression devices, and cefoxitin (2 g IV) should be administered prior to incision. In the operating room, endoscopes to enable evaluation of the stomach and deep intestine should be available.

Surgery is begun by placing an index trocar at 18 cm below the xiphoid in the midline after the Veress needle has been introduced to establish pneumoperitoneum. After remaining trocars are placed, laparoscopic exploration of the abdomen is conducted. The greater omentum is elevated, and the ligament of Treitz is identified. The jejunum is divided into biliopancreatic and Roux limbs at 20 cm distal to the ligament of Treitz. Next, the jejunojejunostomy is performed after a 75 to 150 cm Roux limb is passed toward the proximal gastric pouch, either through the transverse mesocolon (retrocolic) or in front of the colon (antecolic); the retrocolic method may either take a retrogastric or antegastric route. Any mesenteric defects between loops of bowel are potential hernia sites and, therefore, are closed with permanent running suture. The gastric pouch should be between 15 mL and 30 mL in size and is constructed based on the size of the lesser gastric curve. Finally, the gastrojejunostomy is constructed either through circular-stapled, linear-stapled, or hand-sewn techniques, and a surgical drain may be placed.

Potential pitfalls of the procedure include bleeding, inability of the Roux limb to reach the gastric pouch without tension, and unexpected anatomy such as malrotation, enlarged liver, excessive omentum, or thick abdominal wall. Though rare, unexpected findings during a laparoscopic gastric bypass may influence the operative course. These findings could include tenacious adhesions from previous surgery that require lysis, malrotation of the ligament of Treitz necessitating a mirror image approach to the technique, hernia findings that require a change in port placement, or a cirrhotic-appearing liver that may require biopsy or even aborting the case if varices or ascites is noted. A GIST that may not have been revealed with preoperative assessment may be resected in its entirety and the surgery completed as originally planned.

Sleeve Gastrectomy

The vertical sleeve gastrectomy (SG, see Fig. 8.1 E ) involves removing about 80% of the stomach, with a resultant remaining sleeve that is lesser curve-based and is 28 to 32 French (Fr) in diameter. It has been hypothesized that the tighter the sleeve, the more likely the possibility of a leak, which is the most common major complication after SG; other potential pitfalls may include bleeding or strictures. Care should be used while taking down the blood supply to the greater curvature of the stomach. An advanced bipolar cutting device or ultrasonic scalpel is used to seal the blood vessels. At the most proximal portion of the stomach, the short gastric vessels can be in close proximity to the spleen, and the surgeon must avoid excessive traction in this area to avoid a shear injury. A bougie (32 to 40 Fr) is used to guide the staple line along the sleeve. A tight sleeve, especially at the incisura, can lead to outflow obstruction and predispose to a more proximal leak. Many surgeons perform an intra-operative leak test with either air or methylene blue to evaluate the staple line. If the leak test is positive, then the staple line can be reinforced or oversewn in the areas of concern.

Patients are placed in the supine or split-leg position. Five trocars are used and placed at the surgeon’s preference. The liver is then retracted to expose the stomach including the gastro-esophageal junction. The gastro-colic ligament is then divided, and the vessels of the gastroepiploic arcade are cut using an advanced bipolar cutting device or the ultrasonic scalpel. Dissection is carried out along the greater curve of the stomach from 3 to 7 cm proximal to the pylorus up to the angle of His. The stomach is then freed from any posterior attachments within the lesser sac. Care should be taken to avoid injuring the splenic vein and artery during the dissection. A bougie (32 to 40 Fr) or endoscope is then passed into the stomach as a guide for stapling. The sleeve is then created with multiple staple loads from just proximal to the pylorus to the angle of His. The stomach should not be divided too close to the incisura to avoid stricture at this area. Additionally, when stapling, the surgeon should ensure that the anterior and posterior edges are the same distance from the lesser curve so that the sleeve does not kink or twist. Techniques vary in that some surgeons may use buttressing material within their staples. Surgeons may also oversew the staple line or reapproximate the omentum to the new greater curve with interrupted sutures. Drains may be placed at the time of surgery depending on surgeon preference. The patient is admitted for 1 to 2 days postoperatively and started on a liquid diet.

An UGI is performed on postoperative day 1 at some institutions to show free passage of contrast through the sleeve without evidence of extravasation. The patient is given a PPI for 6 months postoperatively as well as multivitamins to be taken for life.

Diet is slowly advanced over 8 weeks as an outpatient from full liquids to pureed food to soft food and finally to a regular diet.

Other Operations

Other operations include gastric banding (GB [see Fig. 8.1 B to C ]). GB has declined precipitously as a result of lack of significant treatment effect and need for reoperation. The GB technique involves a “pars flaccida” or hepatogastric ligament technique whereby a soft, inflatable silicone gastric band is placed immediately below the lower esophageal sphincter as demarcated by the esophageal fat pad.

Biliopancreatic diversion (BPD) with duodenal switch (DS) now accounts for less than 1% of bariatric procedures (see Fig. 8.1 D ).

Surgical Complications

The average 30-day mortality rate is 0.2% for gastric bypass, 0.14% for vertical SG, and 0.02% for GB. Complications can be divided into 3 categories: intraoperative, early postoperative (within 30 days of surgery), and late postoperative (>30 days after surgery). Significant progress has been made to monitor outcomes and develop evidence-based guidelines of criteria and benchmarks that determine safe practices. As mentioned, complication rates are directly related to the experience of the surgeon and hospital.

Complications of bariatric procedures include anastomotic leak or stenosis, pulmonary embolus (PE) and DVT, GI bleeding, nutritional deficiencies, wound complications, bowel obstructions, ulcers, hernias, and respiratory and cardiovascular complications. Among the different surgical procedures, the complication rates are proportional to the amount of weight loss produced by each operation. The odds of serious adverse events at 1 year are: SG, odds ratio (OR) = 3.22, 95% confidence interval (CI: 2.64 to 3.92; RYGB, OR = 4.92, 95% CI: 4.38 to 5.54; BPD+DS, OR = 17.47, 95% CI: 14.19 to 21.52.

Bowel ischemia may result from a twisted Roux limb or internal herniation that occurred during division of the mesentery. Signs of intestinal ischemia are severe abdominal pain, hematochezia, and an acute abdomen.

Early postoperative complications are anastomotic leaks, pulmonary and cardiovascular complications including DVT and PE, and mortality. Anastomotic, gastric pouch, or duodenal leakage occurs with 2.2% of RYGB, 1.0% of vertical banded gastroplasty (VBG), and 1.8% of BPD. Anastomotic leak, most commonly from the gastrojejunostomy or from the SG staple line, usually near the hiatus, is an independent risk factor for mortality. It has been demonstrated that a surgeon’s experience has significant influence on the leakage rate, with a rate of 1% to 2% in experienced hands and up to 5% for surgeons earlier in their careers. Leaks from SG occur infrequently but can be troublesome to treat. Drainage of leaks along with IV antibiotic therapy is first-line therapy. Additional considerations include stent placement and enteral feeding. In complex, chronic leaks, definitive therapy may require re-operation, converting an SG to a Roux-en-Y esophago-jejunostomy.

PE can account for 50% of deaths in the perioperative period. Currently, a combination of anticoagulants and sequential compression devices are used for PE prophylaxis. For patients who are at the highest risk for DVT or PE, including those who have a history of a venous thrombotic event, venous stasis, poor ambulation, pulmonary hypertension, severe sleep apnea, or BMI greater than 60 kg/m ² , an inferior vena cava filter may be temporarily placed preoperatively and has been shown to decrease the risk of PE from 2.94% to 0.63% in a series of 330 patients with such high-risk factors. Cardiovascular complications such as myocardial infarction are also a significant cause of death in the early postoperative period. For this reason, it is important to perform a careful preoperative cardiac evaluation and involve a cardiologist for high-risk patients. Pulmonary complications are more likely in male patients, those older than age 50 years, Medicare patients, or those with chronic lung disease. Persistent vomiting from stomal stenosis increases the risk of aspiration pneumonia or thiamine deficiency. After laparoscopic bariatric surgery, atelectasis can occur at a rate of 8.4%, and, therefore, postoperative early ambulation is essential.

Late postoperative complications include anastomotic stricture, gallstone formation, nutritional deficiencies, bowel obstruction, intussusception, marginal ulcers or ulcers in the remnant stomach and duodenum, fistula, dumping syndrome, and hypoglycemia. Stenosis of the gastrojejunostomy has been reported in 2% to 14% of patients. Stenosis often manifests 4 to 6 weeks postoperatively as vomiting and progressive food intolerance, first to solids and subsequently to liquids. A high incidence of gallstone formation has been well-documented when morbidly obese patients undergo rapid surgically induced weight loss and is due to increased cholesterol delivery to the gallbladder (NIDDK. Dieting and Gallstones 2017. https://www.niddk.nih.gov/health-information/digestive-diseases/gallstones/dieting . Accessed April 4, 2019). Cholelithiasis develops in up to 38% of patients after RYGB. If a patient has gallstones preoperatively, the surgeon may elect to perform a concomitant cholecystectomy; this is less commonly performed with the laparoscopic approach because it is easier to do by open technique than laparoscopically. Gallstone formation occurs secondary to a combination of vagus nerve damage, altered enteric nerve stimulation, decreased gallbladder emptying, and changes in calcium concentration and the bile salt/cholesterol ratio. It has been shown in a double-blind randomized placebo-controlled trial that ursodiol at a daily dose of 600 mg for the first 6 months after surgery reduces the incidence of gallstones to 2%. To reduce the incidence of cholelithiasis, a 6-month course of ursodiol is recommended for patients whose gallbladder is not removed prophylactically. Nutritional deficiencies can be extensive, related to both the changes in anatomy and postoperative sequelae like persistent vomiting. Bowel obstruction occurs in 0.2% to 7% of RYGB patients; the range varies depending on the surgical technique. For example, if the Roux limb is passed in a retrocolic fashion, there are 3 potential hernia sites: mesocolic, jejunal-jejunal, and between the colon and Roux limb. Most bowel obstructions develop 6 to 24 months postoperatively, but they can occur earlier because of technical errors related to mesenteric defects. Bowel obstructions that occur early usually require bowel resection to prevent retrograde distention of the biliopancreatic limb and distal stomach, which could result in rupture of the distal gastric staple line and consequent peritonitis. In later bowel obstructions, surgical intervention is only required after failure of NG decompression, IV fluid resuscitation, and NPO status. When intussusception occurs, it is usually years after surgery. Patients with the highest risk of developing intussusception are those who have lost more than 90% of their excess weight.

Marginal ulcers are ulcers located in the jejunum near the anastomotic site. They are estimated to occur in 1% to 16% of gastric bypass patients. Perforated marginal ulcers occur in 1% of RYGB patients. Ulcer perforation is linked to smoking and use of NSAIDs or glucocorticoids. The use of nonabsorbable sutures, as opposed to absorbable sutures, for the inner layer of the gastrojejunal anastomosis (GJA) is associated with increased ulcer incidence. The presence of Hp also increases risk for marginal ulcers. It is common practice for bariatric surgeons to use PPI therapy for 6 months postoperatively. If a marginal ulcer is recalcitrant to medical therapy, the possibility of a gastric-gastric fistula must be entertained, for which surgical correction is mandated. The remnant stomach maintains a pH of 2 to 3 and still responds to vagal and hormonal stimulation; therefore, ulcers may also occur in the gastric remnant and duodenum years after surgery and independent of Hp status. Endoscopic evaluation of the gastric pouch is challenging given the divided stomach; thus, unstable patients may require surgical exploration. Fistulas occur rarely, and often concurrently with a marginal ulcer. They form most commonly between the gastric pouch and gastric remnant, and are due to a GI leak from the gastric pouch eroding into the gastric remnant. Large, undiagnosed gastrogastric fistulas may result in weight regain. Fistulas leading to weight regain require elective endoscopic or surgical repair.

Dumping syndrome can occur in up to 20% of RYGB patients ; it is classified as early or late depending on how soon it develops after a meal. Early dumping ensues 15 to 30 minutes after eating and is thought to be due to the rapid entry of hyperosmotic foods into the jejunum. It is due to rapid fluid shifts into the intestinal lumen with a meal which results in a parasympathetic response leading to a reduction in systemic vascular resistance, an effect called “splanchnic blood pooling.” Symptoms include cramping abdominal pain, voluminous diarrhea, bloating, dizziness, nausea, flushing, and tachycardia; symptoms result from hypovolemia and a subsequent sympathetic response. Dumping syndrome is triggered by consumption of simple sugars, acidic foods, and nutrient-rich drinks such as Gatorade. Foods high in protein and fiber should be consumed to avoid this uncomfortable syndrome; additional behavior modifications include smaller, frequent meals, lying down after meals, and avoidance of very hot and very cold foods to reduce symptoms related to decreased systemic vascular resistance. Early dumping is usually self-limited and resolves between 7 and 12 weeks after surgery. Late dumping syndrome occurs 2 to 3 hours after a meal and is secondary to rapid glucose absorption, subsequent hyperglycemia, and release of glucagon-like peptide-1 and gastric inhibitory polypeptide. A relatively exaggerated insulin response ensues, leading to hypoglycemia and hypokalemia. Patients present with diaphoresis, weakness, fatigue, and dizziness. The same modifications suggested for early dumping syndrome should also ameliorate the symptoms of late dumping syndrome. Treatment includes dietary and medical interventions to control serum glucose levels.

GI bleeding can occur postoperatively in 2.0% of RYGB, 0.7% of VBG, 0.3% of laparoscopic adjustable gastric banding (LAGB) surgery, and 0.2% of BPD. In RYGB patients, postoperative dysphagia is not significantly worse than the patient’s matched preoperative symptoms and can develop with food indiscretion, stricture formation, or other obstructions.

Beyond the type of procedure, there are identified risk factors for complications after bariatric surgery including older age, male gender, greater BMI, comorbidities, and Medicare insurance status. The increased risk for Medicare patients is beyond age, because eligibility for Medicare is disability, which may affect outcome. Although patients with the greatest number of risk factors carry the highest risk for surgery, they also may derive the most benefit from bariatric surgery, given the disease burden they carry. Of note, complications may not affect long-term weight loss, which is the outcome that best predicts long-term mortality risk.

Nutritional Deficiencies

Nutritional and vitamin deficiencies and electrolyte abnormalities occur in 16.9% of RYGB patients. Patients who do not take daily vitamins postoperatively or patients who experience frequent vomiting are at increased risk of developing such deficiencies, most common of which are protein, iron, vitamin B ₁₂ , folate, calcium, and the fat-soluble vitamins A, D, E, and K.

Prolonged vomiting may result in thiamine (vitamin B ₁ ) deficiency, which can lead to Wernicke encephalopathy, a syndrome of confusion, ataxia, ophthalmoplegia, and impaired short-term memory (see Chapter 103, Chapter 104 ). This neurologic deficit is preventable with appropriate administration of thiamine. If thiamine deficiency is suspected, the patient should be given IV or intramuscular thiamine immediately to increase the chances of symptom resolution. Early treatment is imperative because persistent severe symptoms may not be reversible despite delayed administration of thiamine.

The parietal cells of the stomach produce intrinsic factor (IF), which is necessary for vitamin B ₁₂ absorption in the terminal ileum (see Chapter 103Chapter 103Chapter 104 ). Patients who undergo RYGB may develop B ₁₂ deficiency because RYGB separates the parietal cells in the fundus of the stomach from the smaller gastric pouch. There is, therefore, no contact between ingested food and IF until the intersection of the Roux limb in the jejunum. In addition, the parietal cells of the stomach often cease to produce IF after RYGB, presumably because the fundus no longer has any contact with food. Restrictive bariatric surgery does not cause vitamin B ₁₂ deficiency because the parietal cells in the fundus of the stomach remain in contact with the nutritive stream.

Calcium, iron, and folate deficiency can occur because they are absorbed mainly in the duodenum and proximal jejunum. These segments of the digestive tract are commonly bypassed in gastric bypass surgery. Moreover, vitamin D is necessary for calcium absorption, and vitamin D deficiency further contributes to any calcium deficiency.

Outcomes

The steep rise in bariatric surgery utilization can be attributed to its proved efficacy as a treatment for morbid obesity. Two meta-analyses have provided strong validation that bariatric surgery leads to successful weight loss and mortality reduction. A meta-analysis by Buchwald that included 22,094 patients found the mean percentage of excess weight loss for all patients to be 61.2%. Excess weight loss was highest for BPD with DS (70.1%) followed by VBG (68.2%), RYGB (61.6%), and lowest for LAGB (47.5%). A meta-analysis by Maggard found similar weight loss trends at 3 or more years postoperatively, with the greatest weight loss achieved after the malabsorptive procedures of BPD (53 kg) and RYGB (42 kg), and less weight loss after the restrictive LAGB (35 kg) and gastroplasty (32 kg).

Such substantial weight loss is associated with a clear reduction in long-term mortality. A retrospective cohort study of 9949 RYGB patients matched to 9628 severely obese controls found that having RYGB surgery reduced the adjusted long-term mortality from any cause of death by 40%. Among RYGB patients, mortality was decreased from coronary artery disease by 56%, from diabetes by 92%, and from cancer by 60%. In another study there was a 14% decrease in cancer incidence among patients who underwent RYGB. The biggest reductions in cancer incidence were seen among types of cancers that are considered obesity related: esophageal adenocarcinomas (2% reduction), colorectal (30% reduction), postmenopausal breast (4%), uterine corpus (78%), non-Hodgkin lymphoma (27%), and multiple myeloma (54%). The lower cancer risk of patients after RYGB is presumably due to weight loss, which has been shown in many studies to reduce cancer incidence. Furthermore, once obese patients lose weight, they may have easier access to needed health surveillance like Pap smears and colonoscopy. Finally, given that increased BMI leads to worse surgical oncologic outcomes, it may be surmised that with weight loss, a better surgical outcome may be anticipated.

Overall, bariatric surgery dramatically improves survival and decreases mortality from all disease-related causes of death. Only the rate of deaths not caused by disease (e.g., deaths resulting from accidents and suicide) increased after bariatric surgery and were 58% higher in RYGB patients. One speculation as to why accidents and suicides were higher in the surgical group was the possibility of alcohol abuse. One study demonstrated altered alcohol metabolism after gastric bypass surgery, perhaps explaining a propensity for alcohol abuse. A recent analysis found that due to increased rate of absorption of alcohol after RYGB, there was both an earlier and higher blood alcohol concentration. This concentration was high enough to be defined as a binge drinking episode, which is a risk factor for developing alcohol abuse. One study of bariatric surgery candidates found that 9% reported suicide attempts and 19% reported alcohol abuse preoperatively. There is concern that this vulnerable patient population has additional difficulty with the psychological adjustments to weight loss, which further supports the need for psychologic counseling before and after surgery.

In addition to benefiting from decreased mortality, bariatric patients benefit from decreased morbidity. Morbidly obese patients suffer from more intense GI symptoms such as abdominal pain, heartburn, and sleep disturbances than do normal weight patients. Beyond the significant improvement in cardiac risk factors, weight loss surgery also provides enormous benefit for the many medical problems obesity causes. The reduction in GERD symptoms leads to significantly decreased medication use postoperatively for both PPIs (44% to 9%) and H2RAs (60% to 10%). In fact, GERD resolution rates following RYGB are so robust that RYGB is a suggested treatment for recalcitrant GERD in morbidly obese patients.

Recently, a number of clinical trials have demonstrated a dramatic effect of bariatric surgery on glycemic control in patients with type 2 diabetes, such that the need for medical therapy was decreased or eliminated. Moreover, in a prospective non-randomized case-matched Swedish trial, type 2 diabetes was significantly less likely to develop in obese participants who underwent a bariatric procedure than in their control counterparts. Although this is not an indication that bariatric surgery should be used for the purpose of preventing development of type 2 diabetes in obese patients, nor serve as a replacement for medical therapy, it does suggest that the mechanisms by which bariatric surgery prevents progression from abnormalities in glucose metabolism to frank diabetes is an area that should be explored further.

The effects of obesity are not merely physiologic. Administration of the SF36 survey shows that quality of life improves greatly after RYGB surgery. Preoperatively, morbidly obese patients score significantly lower than USA population norms in the categories of general health, vitality, physical functioning, bodily pain, and emotional and social functioning. As early as 3 months after RYGB, these same patients score no differently than USA norms in these categories.

As bariatric surgery continues to grow, there is increasing recognition that obesity is a chronic and complex disease. As such, there likely will be variations to current therapy, gastric bypass being the most consistent across surgeons. With such variation, there will be the potential for revision of previous surgeries. In fact, revisional surgery now accounts for 15% of total bariatric surgery. Current evaluation of revisional bariatric surgery outcomes indicates that morbidity is low and weight loss is adequate; however, revisional bariatric surgery morbidity is higher and weight loss is lower than morbidity with primary bariatric surgery.

Ulceration

Ulceration at the gastrojejunal anastomosis (GJA) is a common late complication of RYGB. Incidence has varied widely in the literature, but a recent systematic review and administrative database study report incidence rates of 4.6% to 6.28% of patients ( Fig. 8.2 ). GJA ulceration often develops in the first 3 months postoperatively but can occur at any time. Data from an administrative database showed an increase in the rate of surgical intervention for marginal ulceration over time from 6% at 1 year to 17% at 8 years, suggesting a higher morbidity from marginal ulcerations that occur many years later. Patients typically present with epigastric pain, nausea, vomiting, food intolerance, overt or occult bleeding; however, up to 61% of patients are asymptomatic. Moreover, ulcers can occur at any of the anastomoses created during a RYGB.

Anastomotic ulcers may be due to small amounts of acid produced by the gastric pouch, ischemia, bile acid reflux, Hp infection, NSAIDs, smoking, alcohol, foreign bodies such as non-absorbable sutures or staples, or tension on the Roux limb. Gastrogastric fistula and staple line disruption also may result in ulceration from exposure to acid.

Evaluation for anastomotic ulceration may be performed with water-soluble contrast media (e.g., gastrografin) or careful endoscopy any time after surgery. Endoscopic evaluation should include the gastric pouch, GJA, and proximal Roux limb. This may be accomplished with a pediatric colonoscope, however a deep enteroscopy system is often necessary to reach the duodenum and excluded stomach. Size, depth, and potential etiologic factors should be noted for each ulcer. Hp fecal antigen testing may be the easiest and most accurate way to confirm the presence of Hp.

Treatment of ulceration is multifaceted. In patients with RYGB, anastomotic ulcers should be treated with soluble PPI or capsules that are broken open, taken twice daily, and tapered over 6 months. Sucralfate solution at 1 g 4 times daily should be used concurrently when possible; the tablet form of PPI does not appear to be as effective. Bile reflux can be treated with bile acid binders such as cholestyramine or colestipol. Smoking cessation is critical. Control of diabetes should be optimized. NSAIDs should be discontinued, if possible, or combined with PPI or PGE1 therapy if needed long term. Hp should be treated if active infection is found. Visible sutures or staples within the ulcer should be removed. Repeat upper endoscopy to check for healing is recommended at 2 to 3 months after initiation of medical therapy. If the ulcer fails to heal with maximal medical therapy, surgical revision has been the traditional next step in therapy. Endoscopic therapy using an endoscopic suturing system to oversew and cover the ulceration has also been reported in a limited case series.