Obesity surgery

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Chapter 27 OBESITY SURGERY

• Morbid obesity is increasingly prevalent in all developed and developing countries.

• Bariatric (weight-loss) surgery is the only treatment shown to cause measurable weight loss in those severely affected.

• Appropriately performed surgery in appropriately selected patients leads to weight loss, resolution of obesity-related comorbidities, reductions in medical and disability costs and reduced mortality risk.

• Other than the intragastric balloon, all surgical procedures aim to cause permanent changes in gastrointestinal physiology to encourage the durability of weight loss.

• Complications after this type of surgery can occur at any time post-procedure, and can be predicted by the procedure undertaken.

• Endoscopy has an important role to play, and these patients will present to gastroenterologists for care.

• Therapy for these patients cannot be accomplished without an understanding of the underlying anatomy.

DEFINITIONS OF OBESITY

The increasing prevalence of obesity is a worldwide phenomenon and it is a disease with protean adverse physical, social and psychological effects. The classification of obesity defines the relationship between a person’s height and weight, the body mass index (BMI) to stratify patients according to their risk of obesity-related medical conditions (Table 27.1).

TABLE 27.1 Obesity definitions ^*

	BMI (kg/m²)	Obesity class
Underweight	<18.5	–
Normal	18.5–24.9	–
Overweight	25.0–29.9	–
Obesity	30.0–34.9	I
Obesity	35.0–39.9	II
Extreme obesity	40.0+	III

* The term ‘morbid obesity’ relates to BMI 35.0–39.9 with medical comorbidities or BMI 40 and above.

TREATMENT OF OBESITY

There are many dietary, medical and therapeutic options available to clinicians treating patients with obesity and, in general, many of these treatments have been attempted by patients as they progress through various stages of their disease. Non-surgical treatments combining elements of diet, exercise and pharmacotherapy are demonstrated in the published literature to be effective in obtaining modest weight loss and perhaps allowing patients to ‘hold’ their weight, but have no long-term efficacy in those in whom massive sustained weight-loss is required. In general, weight-loss after surgical treatments is 5–10 times greater than that obtained by non-surgical methods, and the results in obesity comorbidity resolution, cost saving and mortality reduction cannot be matched by other methods.

Having surgery entails taking on some risks, so it is obvious that this is not a treatment that can be applied liberally. The effects of any operation, both positive and negative, may be permanent and some complications may develop insidiously many years later and, therefore, may not be related to the operation. Current, generally accepted criteria for selecting patients for surgery are listed in Table 27.2.

TABLE 27.2 Selection criteria for bariatric surgery

Body weight	BMI >40
	BMI 35–39.9 with medical comorbidities
	No endocrine cause
Resistant obesity	Obesity present >5 years
Resistant obesity	Multiple failed non-surgical attempts
Psychological profile	No alcohol or drug use
	No or controlled psychiatric conditions
	Understanding of surgery and commitment to follow-up

Weight-loss surgery

Obesity is a chronic, probably life-long disease and, therefore, the current surgical solutions are designed to cause permanent alterations to gastrointestinal physiology. These physiological alterations, while necessary for the maintenance of weight-loss, may become disordered and lead to the patient presenting for medical or surgical care. There are a range of bariatric surgical procedures currently undertaken, and a number of historical procedures that remain of interest due to the large number of patients who have undergone them in the past. Thankfully there is sufficient homology between all of the historic and current procedures to allow them to be grouped into categories when discussing them. Complications following surgery may be related to weight loss itself (e.g. gallstones), anatomic changes (e.g. vomiting, obstruction) or altered nutritional status (e.g. decreased intake, decreased absorption or gastrointestinal losses). Most of the subtle nutritional complications that can arise after this type of surgery are beyond the scope of this chapter and will not be discussed.

BARIATRIC OPERATIONS

Operations for morbid obesity are grouped into:

• ‘Restrictive’: vertical banded gastroplasty (VBG), fixed band and the laparoscopic adjustable gastric band (LAGB)

• ‘Malabsorptive’: jejunoileal bypass, biliopancreatic diversion, the Scopinaro procedure

• ‘Combined’: Roux-en-Y gastric bypass (RYGBP).

These terms are historically based and fail to take into account the often complex variations between individual operations; they also inadequately explain the mechanisms by which the procedures work.

Gastroplasty

Fixed gastroplasty

Stapled gastroplasty, of which the VBG has been the most frequently performed worldwide, has undergone multiple revisions in technique due to frequent staple-line disruption, stoma problems, reflux, vomiting and weight regain. Silent failure is common with loss of restriction and weight regain following staple line disruption, allowing patients to return to their asymptomatic, albeit obese, preoperative state. Surgeons practising during the 1980s and early 1990s will be familiar with the cruel paradox of the vomiting patient who still gains weight. This peculiarity shows how the term ‘restrictive’ is a misnomer, as an operation that restricts intake without offering satiety after limited solid food intake will enforce liquid calorie intake. Examination of adjustable gastric banding has shown that early satiety is a significant factor in the success of restrictive operations and that early satiety makes procedures that promote voluntary limitation of food intake (LAGB and RYGBP) tolerable to patients.

The main complications likely to cause presentation of VBG and the mechanistically similar fixed band patients relate to the stoma. The natural history of a fixed obstruction in any part of the gastrointestinal tract is proximal dilation, and if this occurs above an excessively tight or scarred stoma, patients experience increasing reflux and regurgitation with inability to tolerate solid food. Increasing the radius of the stomach ‘pouch’ above the obstruction increases the wall tension according to the law of Laplace, and leads to inability of the pouch to empty, which in turn leads to progressive dilation. Reflux, regurgitation and cough are common symptoms of this syndrome, and these symptoms are often associated with the presence of a hiatus hernia. If this complication cannot be controlled with proton pump inhibitors, surgical correction is mandated. Patients having re-operative surgery for complications resulting from an earlier operation should probably be seen by an experienced bariatric surgeon to help ensure a good outcome.

Adjustable gastroplasty

Laparoscopic adjustable gastric band (LAGB) is a procedure that has been responsible for the increase in uptake of bariatric surgery in many countries outside the USA. The band is placed just below the cardia, so that the volume of stomach above the band stoma is a couple of millilitres in size only (Figure 27.1).

FIGURE 27.1 Laparoscopic adjustable gastric band (LAGB).

Bands placed lower on the stomach are often unstable and can ‘slip’ easily with prolapse of the stomach proximally, resulting in reflux and vomiting, which is reminiscent of VBG complications.

Severe perioperative problems after placement of a LAGB are rare, but operation-specific complications include injuries to vascular structures, the liver and spleen, as well as hollow viscus perforation. Early bolus obstruction after discharge, similar to that which occurs in some patients after Nissen fundoplication, may occur if solid food intake has been commenced too rapidly postoperatively, or if the patient has been vomiting with resulting stomal oedema. Perforation of the cardia or oesophagus at the time of surgery will often be missed by the surgeon as placement of the band involves blind dissection behind the stomach where it is bound to the crura of the diaphragm. A perforation at this location may cause significant intra-abdominal, retrogastric and mediastinal sepsis presenting several days after discharge. Any patient with significant pain and a fever following LAGB placement should be treated with extreme concern.

Late LAGB complications usually relate to stomal obstruction. If a band has been overfilled the stoma will be so tight that the patient may be unable to swallow saliva. This problem can invariably be fixed by accessing the port with a Huber (non-coring) needle and emptying the reservoir.

A more difficult cause of vomiting or reflux is stoma obstruction caused by pouch dilation and prolapse of stomach above the band. In extreme cases, this can cause strangulation and necrosis of the proximal stomach, so any LAGB patient in whom vomiting is not relieved by band deflation can be assumed to require an operation to remove or revise the band. Further contrast radiology may cause unnecessary delay and adversely affect the outcome, especially if the patient is unwell or in pain.

Erosion of the band into the stomach lumen is an uncommon occurrence and is usually asymptomatic except for patients complaining of weight regain, although abdominal pain may also be present due to localised sepsis. Eroded bands can usually be removed laparoscopically or endoscopically with surprisingly few sequelae.

Investigating patients after gastroplasty

The majority of patients will present with reflux and dysphagia symptoms, and in most of these cases the underlying pathology will be the result of an ‘obstruction’ with proximal dilation and/or a hiatus hernia. In many cases, the hiatus hernia will be small, and any barium studies will be misreported. In Figure 27.2 only the first barium swallow (left panel) was interpreted correctly as reflux and a small hiatus hernia, the second (second panel from the left) of a VBG with reflux and hiatus hernia and the third (second panel from the right) with reflux and a slipped gastric band were not. Note the transverse lie of the band on the AP radiograph, which is a finding that is always associated with anterior pouch prolapse. The correct orientation of the band is seen on the fourth image (right panel), with the lie of the band pointing at 2 o’clock on the anteroposterior film.

FIGURE 27.2 Barium studies post gastroplasty in four patients (three reflux patients, and one normal). The left panel shows a small hiatus hernia, second on the left shows a VBG and hiatus hernia. Second panel from the right shows a slipped gastric band and the right panel shows a normal barium swallow after successful gastroplasty.

At endoscopy there may or may not be evidence of oesophagitis, and care must be taken to look for a small hiatus hernia. Other studies, such as manometry or oesophageal pH studies are of no assistance and may give misleading results, especially as some gastroplasty patients can develop a ‘pseudoachalasia’ syndrome that cannot be properly characterised without removal of the obstructing lesion.

Acute post-gastric reduction surgery (APGARS) neuropathy

Any patient who suffers from intractable vomiting after an operation that has a gastroplasty component is at risk suffering a preventable and only variably reversible polyneuropathy—the acute post-gastric reduction surgery (APGARS) neuropathy. This is characterised by vomiting, significant and rapid weight loss and a constellation of symptoms that may include ‘tingling’, hyporeflexia, weakness and syndromes resembling Wernicke’s or Korsakoff ’s psychosis. These patients typically have not been taking or absorbing mineral and vitamin supplements and may also be suffering from occult or suboptimally treated surgical complications. Admission to hospital, B₁₂, thiamine and multivitamin supplementation and search for and correction of surgical complications is recommended.

Malabsorptive operations

The pioneer bariatric operation was the jejunoileal bypass and, although the majority of patients undergoing this procedure lost a lot of weight, they did so at the expense of frequent and uncontrollable side effects including liver failure and profound malabsorption. Most of these patients have had the procedure reversed, but the legacy of procedures that work by inducing a malabsorption syndrome remains.

Of the current malabsorptive operations, the Scopinaro and biliopancreatic diversion (BPD) procedures are the most effective long-term operations available with regards to maintenance of weight loss, and they have unparalleled results in diabetes and hyperlipidaemia resolution. They involve a limited gastrectomy and subtotal small intestine bypass which is achieved by anastomosing the ileum to the stomach (or pylorus), and bypassing the entire jejunum which is then anastomosed to the terminal ileum. Typically patients will have a short ‘enteric limb’ in which carbohydrate is absorbed and a ‘common channel’ of 25–100 cm of terminal ileum where biliary and pancreatic juices are mixed with the food to allow limited fat absorption.

In essence, these operations convert patients with an uncontrolled obesity and metabolic disorder to patients with a controllable malabsorption and deficiency syndrome, but the margin for error is small and tolerance to the operation appears individually variable. Patients who have had these operations need strict lifelong supervision to avoid potentially dangerous and irreversible metabolic sequelae. Some patients require reversal or revision of the operation because of nutrition problems despite compliance, and those who stop taking supplements will develop marked osteopenia, fatigue, iron deficiency and fat soluble vitamin deficiency (A, D, E, K). Uncommonly, night blindness and other syndromes may develop. Complications resulting from stasis in the bypassed intestine are uncommon in modern forms of the operation but may present sporadically. A patient who is lost to follow-up after one of these operations who presents to another clinician should be treated with these deficiencies in mind and specialist help should be sought from either the operating surgeon or an endocrinologist. These patients have limited reserve and can become dehydrated and hypoalbuminaemic easily, so the patient should be admitted for all but the most trivial illnesses.

Gastric bypass

Gastric bypass is the most frequently performed bariatric procedure performed worldwide, and it may be performed via a laparoscopic or open approach. Gastric bypass is essentially just that, a bypass of the stomach, and gastroenterologists dealing with these patients can consider that they have had an operation analogous to a total gastrectomy (Figure 27.3).

FIGURE 27.3 Roux-en-Y gastric bypass.

Gastric bypass is essentially a ‘restrictive’ operation with strong satiety regulation mediated by early release of peptide YY and anorexic hormones after meals. This, and changes to small intestine motility, also leads to intolerance of high-density carbohydrate which will cause nausea and symptoms of ‘early dumping’. The operation does not lead to protein or fat malabsorption as the length of the small intestine bypass is trivial. Bypassing the stomach will prevent acidification of the enteric stream and therefore cause potential but unpredictable and individually variable reductions in calcium, iron and B₁₂ absorption.

Outside the early postoperative period where a therapeutic endoscopist may be asked to plug, glue or stent a leaking enteric anastomosis, potential complications revolve around the excluded stomach, the gastrojejunal anastomosis and bowel obstruction.

The excluded stomach is surprisingly quiescent in these patients, and despite the obvious concerns regarding ulcer disease the reported rate of ulceration requiring treatment seems low. Long-term use of non-steroidal antiinflammatory drugs is not advised, and access to the stomach for endoscopy or endoscopic retrograde cholangiopancreatography (ERCP) will require additional laparoscopic or percutaneous techniques. The gastrojejunal anastomosis may become stenosed in about 5% of patients, and in the majority of cases this will be amenable to endoscopic balloon dilation; 12 mm dilation is usually sufficient to resolve symptoms.

The most significant complication following gastric bypass surgery is the risk of small bowel obstruction and internal herniation of bowel through mesenteric defects with volvulus or ‘closed-loop’ obstruction. This can present insidiously as recurrent abdominal pain, sometimes mimicking biliary colic, pancreatitis, or appendicitis. Vomiting and obstipation may occur very late in the clinical course of the illness as a prelude to or a result of intestinal infarction. Plain abdominal radiology is unreliable or misleading, but high-resolution computed tomography (CT) with oral and intravenous contrast will usually diagnose those with evolving obstruction, often only recognised as an abnormality in mesenteric vasculature. For patients with intermittent or recurrent symptoms, laparoscopy is the only diagnostic test with sufficient predictive value to either prove or disprove recurrent obstruction, and elective repair of any defects is usually straightforward.

SUMMARY

Bariatric surgery complications are common. Potential complications can be grouped into:

• Gastroplasty complications—vomiting, stomal obstruction, gastroenterostomy stricture and reflux (VBG, fixed and adjustable bands, gastric bypass)

• Excluded organ complications—bacterial overgrowth, peptic ulceration, occult bleeding (gastric bypass, intestinal bypass procedures)

• Intestinal obstruction and internal herniation (gastric bypass, intestinal bypass procedures)

• Gallstone disease (all)

• Malabsorption or decreased intake of, or abnormal loss of, protein, vitamins and minerals (all).

Most of these complications can be managed once a clear understanding of the underlying anatomy and, therefore, physiology has been obtained. Obtaining old records can be crucial in this regard. It should be recognised that many of these problems are complications rather than expected outcomes, and that anatomic defects underlying the complications may necessitate surgical correction.

FURTHER READING

Buchwald H, Buchwald J. Evolution of operative procedures for the management of morbid obesity 1950-2000. Obes Surg. 2002;12:705-717.

Buchwald H, Williams SE. Bariatric surgery worldwide 2003. Obes Surg. 2004;14:1157-1164.

Colquitt J, Clegg A, Sidhu M, et al. Surgery for morbid obesity. Cochrane Database Syst Rev. 2, 2003. CD003641

Dixon AF, Dixon JB, O’Brien PE. Laparoscopic adjustable gastric banding induces prolonged satiety: a randomized blind crossover study. J Clin Endocrinol Metab. 2005;90:813-819.

Greenway SE, Greenway FL, Klein S. Effects of obesity surgery on non-insulin-dependent diabetes mellitus. Arch Surg. 2002;137:1109-1117.

Livingston E. Obesity and its surgical management. Am J Surg. 2002;184:103-113.

Vage V, Solhaug JH, Berstad A, et al. Jejunoileal bypass in the treatment of morbid obesity: a 25-year follow-up study of 36 patients. Obes Surg. 2002;12:312-318.

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