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Obesity Surgery and its Complications

Obesity Surgery and its Complications

In some countries obesity is considered a health crisis. Obese people have an increased risk of many health problems including arthritis, sleep apnea, diabetes, cardiomyopathy, psychosocial impairments, hypertension, malignancy, pulmonary disease, infertility and hyperlipidemia. Many of these comorbidities can be improved by intentional weight loss

Much effort has gone into the development of effective treatment modalities focused on sustained weight loss. However, in achieving and maintaining long-term results in morbidly obese patients, conservative medical treatment such as exercise, dietary regimen, and behavioral modification haven’t been successful. Despite the fact that medical therapy was initially promising, but it has been limited by their inability to maintain significant weight loss over long follow-up periods, and by the side effects of the drugs. Because of this, obese people at risk for medical complications of obesity require more aggressive treatment. Taking all these things into consideration, surgery has become an attractive alternative because the solution that it presents is long-term.


The operations that involve reducing the size of the gastric reservoir with or without associated malabsorption are collected under the name bariatric surgery. With about 50% or more reduction in excess body weight by 18 to 24 months post operation, these operations have achieved impressive results. The number of bariatric surgeries is rapidly increasing, and it has been estimated that about 60,000 to 100,000 bariatric surgeries will be performed next year. A significant number of these people will develop postoperative gastrointestinal symptoms despite the fact that most patients end up achieving successful outcomes. However, whether these symptoms represent “necessary evils” which are adverse events related to dietary indiscretion, or “unnecessary evils” which are postoperative complications, is quite difficult to interpret clinically and usually require gastrointestinal consultation. In this article, the gastroenterologist will become familiar with the various operations, the gastrointestinal complications associated with these operations, and their management in a case-presentation format.



There are multiple operative approaches to bariatric surgery, but 2 main procedures exist in combination, or alone, in the various procedures, these are:


  • Restriction
  • Malabsorption


By mechanically decreasing the volume capacitance of the proximal stomach (eg. vertical banded gastroplasty and gastric banding), the restrictive component limits the volume of solid food that can be ingested. While in the case of the malabsorption component, a diversionary operation is involved in which part of the small intestine is bypassed establishing a partial and selective malabsorption (gastric bypass and biliopancreatic diversion with or without duodenal switch).


In the case of well-informed, highly motivated patients suffering from severe impairments secondary to their weight, bariatric surgery is considered an appropriate treatment option with acceptable operative risks. However, optimal results are obtained with the involvement of a multidisciplinary team including a dietitian, physician/surgeon, nutritionist, psychiatrist and/or psychologist. Additionally, not all patients are considered candidates for these procedures.


To identify patients at risk of developing adiposity-related complications, current guidelines use the BMI classification scheme. BMI is calculated as weight (kg) divided by height (m2); it represents the relationship between height and weight. A National Institutes of Health Consensus Conference in 1991 proposed a risk-classification system based on BMI: Patients with a BMI of 30 kg/m2 or more are classified as obese, while those with a BMI of 25.0 to 29.9 are classified as overweight. Obesity is further classified as:


  • High risk (class I, BMI 30 to 34.9 kg/m2
  • Very high risk (class II, BMI 35 to 39.9 kg/m2
  • Extremely high risk (class III, BMI 40 kg/m2 or greater


The National Institutes of Health concluded that patients who are eligible for surgery are those with class II obesity (BMI 35 to 39.9 kg/m2) and one or more severe, obesity-related medical problems including type 2 diabetes mellitus, heart failure, hypertension and/or sleep apnea, or those with class III obesity (BMI 40 kg/m2). In addition to this, patients should be committed to comply with long-term treatment and follow-up, should have acceptable operative risks and should have failed conventional weight-loss therapies.


Most bariatric surgeries have been performed laparoscopically with success. The laparoscopic approach is gaining favor because of its:


  • Shorter hospital stays
  • Improved cosmesis
  • Less blood loss
  • Faster return to functional daily activities
  • Lower incidence of incisional hernia
  • Decreased wound infections


The majority of studies have also demonstrated that there isn’t any difference in achieved weight loss after the open or laparoscopic procedure. However, because of limitations in the physical anatomy of superobese patients whose BMI is greater than 50 kg/m2, laparoscopy isn’t the preferred surgical approach.




Vertical banded gastroplasty (VBG):

In this procedure, a vertical pouch is created by stapling the front to the back wall of the stomach below the esophagogastric junction. Either a 1-cm diameter polypropylene band (VBG) or a 1-cm silastic ring (vertical ring-banded gastroplasty; figure one), constricts the end of the newly created gastric pouch. These procedures aren’t as effective as other bariatric operations in achieving long-term reduction in excess weight (about 25 to 45% of patients maintain their weight loss), despite the fact that they are simple and relatively safe.

Figure one: Vertical banded gastroplasty (VBG):


Staple line disruption, gastroesophageal reflux, pouch dilation, stomal stenosis, and erosion of the band are some of the complications associated with vertical banded gastroplasty. Some of the complications (stenosis and gastroesophageal reflux) have become so severe, that they warranted conversion of VBG to other bariatric surgeries, most commonly gastric bypass. Additionally, rapid weight gain may result from staple line disruption, which occurs in about 35% of patients.


Gastric banding:

To restrict oral intake creating an hourglass effect (figure two), a silastic band is placed in gastric banding below the esophagogastric junction. This operation is purely restrictive. However, gastric banding helps reduce operative risk and complication rates because it doesn’t involve surgically entering the gastrointestinal tract.


Figure two: Adjustable laparoscopic banding:


In this procedure, to create a restrictive pouch, a band is placed around the stomach laparoscopically. The balloon in the band is connected to a port that is placed subcutaneously and can be accessed to inflate or deflate the balloon, changing the size of the band circumference as a consequence.

In some parts of the world, this laparoscopic banding system is the most popular bariatric surgery. In June 2001, the FDA approved this surgery to be used clinically. In Europe, the long-term results of this surgery have been favorable. Gastric pouch dilation, esophageal dilation, band stenosis, band slippage or migration and band erosion are some of the complications that are associated with this procedure.


Gastric bypass (Roux-en-Y gastric bypass):

This procedure (RYGBP) is mainly a gastric-restrictive one. However, the thing that contributes to weight loss by causing malabsorption of calories and inducing a dumping syndrome in this procedure is the diversionary component of the Roux limb that passes the distal stomach, duodenum, and upper jejunum. A small pouch is constructed by stapling or transecting the proximal stomach (figure three), which is similar to VBG. Most surgeons believe that the pouch should be as small as possible and that the stomal outlet should be about 1 cm in diameter, however, no randomized clinical trials have been performed to evaluate the optimal pouch size. Based on the size of the patient, the length of the limb can be varied. Most limbs are currently 50 to 100 cm in length.


Figure three: Roux-en-Y gastric bypass (RYGBP):


In achieving sustained weight loss, gastric bypass procedures have been very effective. Up to 68% reduction in excess weight has been reported by Pories and colleagues; and weight loss maintained for up to 14 years. RYGBP is quickly becoming the procedure of choice for bariatric surgeons due to these results. Anatomic leak leading to peritonitis, anastomotic ulceration and stenosis, acute gastric distention, internal hernias, hemorrheage, and staple line disruption are some of the complications that are associated with this procedure.


Biliopancreatic diversion:

This procedure (BPD) has two components: the creation of a long-limb Roux-en-Y anastomosis with a short 50 cm alimentary channel and a limited gastrectomy. The former is done by transecting the small intestine about 250 cm from the ileocecal valve and attaching the distal end to the gastric pouch; and then, the proximal end is joined near the ileocecal valve (figure four A). In this procedure, there is no defunctionalized small intestine, making it different from jejunoileal bypass. The defunctionalized small intestine was believed to be responsible for many of the liver abnormalities associated with jejunoileal bypass, making the distinction between these two procedures quite important.

Figure four A: Biliopancreatic diversion (BPD) a limited gastrectomy is created, and the transected ileum is anastomosed to the gastric pouch.


Figure four B: BPD with duodenal switch: In this procedure, to maintain the pylorus and avoid anastomotic complications, a sleeve gastrectomy is created. The transected, distal small bowel is connected to the stomach via a small part of the first portion of the duodenum, similar to a classic BPD.


Particularly in the first year after the surgery, this procedure could result in significant weight loss through a decrease in oral intake and induction of a significant amount of malabsorption, the diversion of bile and pancreatic secretions to induce fat malabsorption, which acts to maintain weight reduction in the long term. Achieving a 65% to 75% loss of excess body weight, this procedure has been quite successful. However, due to concerns that the malabsorptive component may result in serious nutritional complications, critics have thwarted acceptance of this procedure. BPD patients must take lifelong supplemental vitamins and calcium to avoid these problems. Protein malnutrition is the most serious potential complication that usually requires two to three weeks of hyperalimentation and hospitalization and is associated with:


  • Anemia
  • Alopecia
  • Hypoalbuminemia
  • Ascites
  • Edema


An extremely promising alternative to BPD could be BPD with duodenal switch. When compared with traditional BPD, it seems that BPD with duodenal switch can achieve comparable weight loss with fewer side effects. A 70% to 80% greater curve gastrectomy, also called a sleeve gastrectomy, is involved in this procedure, in addition to the maintenance of the pylorus and a small part of the duodenum, as well as the construction of Roux-en-Y duodenoenterostomy (figure four B: the biliopancreatic limb acts to divert bile from the contents of the alimentary canal, while the efferent limb acts to decrease caloric absorption). The possibility of stomal ulcers and dumping syndrome is reduced by the maintenance of the pylorus and duodenal system and the nutrient absorption is preserved, making this procedure unlike the unmodified BPD. Proponents of this technique purport that it almost entirely eliminates these complications.



Complications of bariatric surgery could be divided into ‘true’ complications associated with the operation, and ‘side effects’ associated with the alteration in the upper gastrointestinal anatomy. Bariatric surgery has less than 1% risk of perioperative mortality, 75% of which is associated with anastomotic leaks with peritonitis, while 25% is associated with pulmonary embolism. An anastomotic leak could either cause overt symptoms with frank peritoneal signs, or it could cause vague symptoms such as mild abdominal pain, alteration in urination and bowel frequency, back pain, unexplained tachycardia or shoulder pain. There should be a low threshold for evaluation with water-soluble contrast agents and surgical exploration because of the devastating outcome of anastomotic leaks. Acute gastric distention secondary to edema and obstruction at the enteroenterostomy is yet another early complication of gastric bypass surgery, which may result in staple line dehiscence or gastroenterostomic leaks. Reoperation with tube gastrostomy or radiographic-guided percutaneous gastrostomy could be used to treat acute gastric distention.


Bariatric surgery may cause some of these complications:


  • Stomal ulceration
  • Staple line disruption
  • Anastomotic leak
  • Stomal stenosis
  • Internal hernia
  • Acute gastric distention


Some of the side effects of bariatric surgery may include:


  • Nutrient deficiency
  • Nausea
  • Vomiting
  • Cholelithiasis
  • Dumping syndrome
  • Diarrhea


Certain side effects of bariatric surgery can be expected given the alteration in the upper gastrointestinal anatomy and ameliorated through postoperative treatment and patient education. Moreover, gastric bypass surgery patients should take a multivitamin containing B-12 and folate, along with a calcium supplement, and should be monitored for nutritional deficiencies. Symptoms of iron deficiency and anemia are experienced by many patients. Especially in women who are menstruating, these are potentially serious problems after gastric bypass surgery. Duodenal bypass and surgery-induced iron malabsorption make these women especially susceptible to iron-deficiency anemia when combined with blood loss during menses. These patients are recommended prophylactic oral iron supplementation.


Nausea and vomiting:

After bariatric surgery, the most common complaints are nausea and vomiting, which are usually associated with inappropriate diet and noncompliance with a gastroplasty diet, such as eating undisturbed, chewing meticulously, never drinking with meals, and waiting two hours before drinking after solid food is consumed. However, an alternative diagnosis must be explored in case these symptoms are associated with significant dehydration, epigastric pain, or not explained by dietary indiscretions. Anatomic ulcers, with and without stomal stenosis is one of the most common complications that causes nausea and vomiting in gastric bypass patients. Gastric bypass patients have 3 to 20% chance of ulceration or stenosis at the gastrojejunostomy of the gastric bypass.

Figure five A: anastomotic ulcers, gastric
Figure five B: anastomotic ulcers, jejunal or marginal ulcer.


Most experts agree that the pathogenesis is likely multifactorial despite the fact that no unifying explanation for the etiology of anastomotic ulcers exists. A combination of preserved acid secretion in the pouch, tension from the Roux limb, ischemia from the operation, nonsteroidal anti-inflammatory drug use, and perhaps Helicobacter pylori (H. pylori) infection are thought to be the cause of these ulcers. Staple line dehiscence may lead to excessive acid bathing of the anastomosis, but evidence suggests that little acid is secreted in the gastric bypass pouch. Antisecretory therapy with proton-pump inhibitors and/or sucralfate plus avoiding NSAIDs are all involved in treatment for both marginal ulcers and stomal ulcers. Additionally, if H pylori infection is present, it should be identified and treated.


Stomal stenosis after gastric bypass may obviate the need for surgical revision because it may respond to endoscopic dilation with through-the-scope balloon dilators. Nausea and vomiting secondary to stomal stenosis, erosion of the restrictive band or ring, and increased gastroesophageal reflux may develop in patients with restrictive procedures such as VBG. Treatment will depend on the etiology, and it is unlikely that these patients will respond to balloon dilation secondary to the noncompliant ring or band. Severe gastroesophageal reflux disease may also be associated with VBG and, if present, may require conversion to a gastric bypass or proton-pump inhibitor therapy.


Internal hernia is yet another cause of mechanical obstruction in gastric bypass patients. This may occur at the mesenteric defect at the jejunojejunostomy or where the Roux limb passes through the transverse mesocolon. However, because diagnostic radiographic studies can be normal and because its symptoms are nonspecific including cramping, vomiting, and periumbilical pain with or without nausea, diagnosing this problem is quite difficult. Surgical exploration will be indicated to rule out internal hernia in case symptoms persist or become worse.



Patients may also develop symptoms related to increased transit of ingested food directly into the small bowel (“dumping syndrome”), in addition to the obstructive complications. With food containing a high sugar content and high osmotic activity, symptoms related to dumping syndrome worsen. Patients might present with symptoms of bloating, lightheadedness, nausea and abdominal pain. Usually, these symptoms are a deterrent to overeating and go away with fasting. The other component of the dumping syndrome that will improve with fasting is diarrhea. However, stool studies should be obtained in case a patient has greater than three watery tools per day in spite of fasting and dietary restriction. Empiric antibiotics should be considered in patients who show no improvement with fasting in the context of negative stool studies because gastric bypass patients may be predisposed to bacterial overgrowth and blind loop syndrome.


Gastrointestinal bleeding:

One of the uncommon complications of bariatric surgery is gastrointestinal bleeding. Gastrointestinal bleeding in patients with VBG or gastric bypass should be evaluated similarly to how one would evaluate patients without surgery. However, in patients with gastric bypass, anatomic considerations pose both diagnostic and therapeutic dilemmas. In patients who have undergone gastric bypass surgery, upper gastrointestinal bleeding may occur in the esophagus, Roux limb just distal to the anastomosis, and gastric pouch. But the good news is that these areas are readily accessible to standard upper endoscopy and therapy. Anastomotic ulceration is a rare cause of bleeding and is typically associated with concomitant NSAID use, even though it is present in up to 20% of patients after gastric bypass. However, it is still somewhat controversial whether H pylori infection is an important risk factor for anastomotic ulceration. Additionally, it is not unreasonable to test patients preoperatively and institute treatment if they are H pylori-positive to avoid future complications, because of the increased lifetime risk for peptic ulceration.


Endoscopy may not be able to access the distal stomach and proximal duodenum, but bleeding from these areas is rare because of low-acid secretory states secondary to vagal interruption, restricted contact with food, and lack of antral distention. Patients should avoid NSAIDs if possible, because they are still susceptible to complications related to these medications. A pediatric conoloscope or enteroscope could be used to evaluate the area in case bleeding is suspected from the distal stomach or proximal small bowel. Moreover, the bleeding lesions in this area could be located and treated with interventional angiography. In patients who have undergone obesity surgery, performance of colonoscopy is unchanged; however, because these people are unable to tolerate large volumes orally, care should be given to the preparation.



About one/third of patients may develop gallstones after bariatric surgery, because obesity and rapid weight loss are known risk factors for gallstone formation. Additionally, because of complaints related to gallstones, 10 to 15% of all patients will require cholecystectomy. To prevent complications of cholelithiasis, some centers routinely perform cholecystectomies with bariatric procedures, while other centers choose to administer ursodiol as prophylaxis for 6 months postoperatively. In decreasing the incidence of gallstone formation, two controlled trials demonstrated the efficacy of six months of ursodiol therapy. Cholelithiasis was detected in 22 to 32% of controls vs. in 2 to 3% of treated patients at 6 to 12 months. Clinicians who are against prophylactic cholecystectomy suggest that a cholecystectomy may be easier to perform after weight loss has occurred and that the operation may increase the overall operative time and length of hospital stay.


Prepared By: Dr. Mehyar Al-Khashroum
Edited By: Miss  Araz Kahvedjian

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