Overview of gastric bypass surgery

ARTICLE IN PRESS International Journal of Surgery Open ■■ (2016) ■■–■■

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International Journal of Surgery Open j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / i j s o

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Review Article

Overview of gastric bypass surgery Q1 Elroy Patrick Weledji *

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Department of Surgery, Faculty of Health Sciences, University of Buea, Cameroon

A R T I C L E

I N F O

Article history: Received 7 June 2016 Received in revised form 17 September 2016 Accepted 19 September 2016 Available online Keywords: Gastric bypass Indications Complications Sequelae

A B S T R A C T

Gastric bypass surgery is indicated for several clinical reasons including benign and malignant upper gastrointestinal tract pathologies. Any gastric resection or bypass procedure interferes with gastric emptying and the aim of reconstruction is to minimize the disturbance to the upper gastrointestinal physiology. Gastric bypass procedures induce early satiety, with or without concomitant impaired absorption of nutrients, and offer the best solution for morbid obesity. The long-term health benefits of gastric bypass surgery for morbid obesity must be found to outweigh the operative risks and side-effects of gastric bypass and thus patient selection is fundamental. The aim of the study was to review the indications, complications, sequelae and outcome of gastric bypass procedures. © 2016 Published by Elsevier Ltd on behalf of Surgical Associates Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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1. Introduction

2. Gastrojejunostomy

The history of gastric bypass surgery began in 1880 when the Polish surgeon Ludwik Rydygier performed a gastroenterostomy for peptic ulcer disease [1]. In 1885, the Austrian surgeon Theodor Billroth (Fig. 1) performed a first-stage gastrojejunostomy to alleviate the symptoms of an obstructing large pyloric tumour followed by a second-stage resection of the tumour with restoration of gastroduodenal continuity [1,2]. Most modern forms of gastrectomy with gastrojejunal anastomosis (Billroth II) are modelled on this operation and described for the treatment of peptic ulcer disease in 1911 [2–4]. With the success of antral Helicobacter pylori eradication triple therapy for peptic ulcer disease which includes antibiotics and a reversible chemical vagotomy with H2 receptor antagonist or proton pump inhibitor, surgery is now indicated only for the emergency complications of perforation, severe vomiting from pyloric stenosis and haemorrhage [5]. It was also well recognized that Billroth II (partial) gastrectomy is associated with weight loss and several variations of this procedure have been used effectively in the surgical treatment of morbid obesity with benefit lasting for up to 10 years [4,6–11]. The restriction of volume of ingested food together with altered absorption of nutrients, especially fat contributes to achieving the weight loss and the malabsorptive procedures alter the digestive process in different ways [8–11]. The aim of this review was to evaluate the common gastric bypass procedures with regard to their indications, sequelae and outcome.

By diverting gastric acid away from the duodenum, anastomosis of the stomach to a loop of jejunum was once used to treat duodenal ulcer but carried a high recurrence (50%) rate [12]. Gastrojejunostomy was then used as a drainage procedure following truncal vagotomy for peptic ulcer disease but has fallen into disuse since the advent of effective medical treatment to suppress gastric acid output and antral helicobacter pylori invasion [13,14]. Laparoscopic gastrojejunostomy (LGJ) has been proposed as the technique preferred over open gastrojejunostomy for relieving gastric outlet obstruction (GOO) due to malignant and benign disease with improved outcome and an acceptable complication rate [15]. Gastrojejunostomy would also bypass congenital pre-ampullary duodenal obstruction from a duodenal web/atresia/stenosis and an annular pancreas, with no or minimal early or long term complications including malnutrition [16]. Although resection of a primary gastric tumour provides better palliation than bypass surgery provided the patient’s general health will allow this, patients with unresectable distal gastric tumours may benefit from a high antecolic gastrojejunostomy [17–19]. The control of the rate of delivery of the gastric contents to the small intestine that allows adequate mixing with bile and pancreatic juices and avoids overwhelming the digestive and absorptive capacity of the small intestine requires an intact and innervated pylorus. The importance of attempting to preserve normal gastric emptying in gastric bypass procedures without compromising oncological results is seen with the more physiological post-operative digestive function of the pylorus – preserving partial pancreaticoduodenectomy for pancreatic head cancer than with the partial stomach resection of the classical Kausch–Whipple procedure [20]. The Whipple’s procedure is also occasionally indicated in cases of duodenal or pancreatic head trauma. Following a

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* Department of Surgery, Faculty of Health Sciences, University of Buea, PO Box 126, Limbe, S. W. Region, Cameroon. E-mail address: [email protected].

http://dx.doi.org/10.1016/j.ijso.2016.09.004 2405-8572/© 2016 Published by Elsevier Ltd on behalf of Surgical Associates Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

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Fig. 1. Diagram of Billroth II gastrectomy.

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retroperitoneal duodenal injury, options for duodenal repair may include a pyloric exclusion effected through a gastrostomy. The pyloric ring is closed with a continuous suture or stapling which breaks down after several weeks. The procedure is combined with a gastrojejunostomy and the addition of octreotide and intravenous acid suppression may improve duodenal healing and decrease stomach ulceration. Roux-en-Y loop (Roux-en-Y duodenojejunostomy) drainage of the defect from significant tissue loss in the second part of the duodenum is the procedure of choice in the stable patient [21]. Both the duodenum and the bile duct are triply bypassed with a gastroenterostomy, and a retrocolic Roux-en-Y hepatico-jejunostomy for a duodenal obstructive, locally-advanced pancreatic head carcinoma [22]. However a prophylactic gastrojejunostomy may suffice for an obstructive unresectable periampullary carcinoma [23]. 2.1. Complications Early technical complications from a gastrojejunostomy would include: (a) haemorrhage which is usually from the gastric side of the anastomosis and usually only starts when the clamps are released, by which time the lumen is not visible. It occasionally requires exploration; (b) leakage may occur as a result of tension on the anastomosis. Difficulty in bringing the stomach and jejunum together without tension may require opening the gastrocolic omentum and performing a retrocolic posterior gastroenterostomy. Otherwise, there is little advantage over the simple antecolic gastroenterostomy [24,25]; (c) an internal hernia if the mesenteric defects are not closed; (d) sepsis, either as a wound infection or an intraabdominal abscess; (e) early obstruction follows oedema around the stoma or kinking, or, later due to progression of malignancy especially if done for palliation. Late complications include stomal ulceration which can be prevented by proton pump inhibition and pancreatitis due to afferent loop obstruction [6,24]. 3. Billroth II gastrectomy The Billroth II gastrectomy is often indicated for refractory peptic ulcer disease and gastric adenocarcinoma [14,26,27]. Except in the aged, most surgeons now opt for a partial gastrectomy to treat a resistant peptic ulcer after excluding acid hypersecretion from a pancreatic islet cell gastrinoma [14,26]. Following resection of the distal stomach, reconstruction can be performed by either fashioning a new lesser curve and creating an end-to-end gastroduodenal anastomosis (Billroth I gastrectomy) described in 1881, or, by an endto-side anastomosis of the gastric remnant to a loop of jejunum, with closure of the duodenal stump (Billroth II or Polya gastrec-

tomy) (Fig. 1) [2–4]. The Polya gastrectomy with retrocolic end-toside gastrojejunostomy has become a commonly performed modification of the Billroth II procedure [2]. Franz von Hofmeister described a partial gastrectomy with a retrocolic gastrojejunostomy involving the greater curvature [2,28]. Reconstruction following partial gastrectomy may be simple or difficult depending partly on the build of the patient and partly on the extent and nature of the disease process. Thus Billroth II gastrectomy is usually used for an emergency perforated large duodenal ulcer not suitable for simple omental patch closure and when a duodenal anastomosis (Billroth 1) cannot easily be made [29]. A Billroth I gastrectomy is not a bypass procedure and is suitable for a resistant benign gastric ulcer after excluding malignancy [14,27]. The Billroth II is associated with problems of bile reflux into the gastric remnant and oesophagus, and a higher risk of stomal ulceration. Thus, approximately two-thirds of stomach should be resected to avoid repeated antral exposure to bile [6,14]. For the theoretical benefits of delaying gastric emptying and preventing reflux of duodenal contents into the stomach, a Hofmeister ‘valve’ can often be fashioned by reducing the stoma length to around 5 cm through closing part of the opening in the gastric stump and the rest being used for the actual anastomosis [28]. 3.1. Complications Billroth II gastrectomy was favoured for many years for its relatively low peptic ulcer recurrence rate (less than 5%) [2,4,6]. However, it has a high mortality and complication rate [6,14]. Leakage may occur from either the duodenal stump or from the anastomosis. Leakage from the duodenal stump is usually due to afferent loop obstruction. This risk is reduced by the formation of a Roux-en-Y reconstruction. If there is controlled leak without sepsis or generalized peritonitis conservative treatment is indicated with parenteral nutrition. Otherwise exploration is required to drain any sepsis and to establish drainage of the afferent loop. A useful technique for the latter is to insert a T tube into the duodenum and, therefore, establish a controlled fistula, and to decompress the afferent loo obstruction [6,30,31]. It is unlikely that direct suture of a leak will be feasible. Treatment of a gastrojejunal leak is problematic. More commonly the leak is delayed, occurring 7–14 days postoperatively. If there are clinical features to indicate that this is limited and localized, then conservative treatment with nutritional support, gastrointestinal decompression and antibiotics is indicated .Otherwise, reoperation is required. 3.2. Side effects and post-prandial sequelae 3.2.1. Early satiety Early satiety arises from the loss of reservoir function of the stomach and it is important to obtain good early dietary advice and limit meal size. The excision of 80% of the stomach leads to reduced gastric volume resulting in early satiety and hence weight loss. Gastric bypass surgery not only reduces the gut’s capacity for food but also dramatically lowers ghrelin levels compared to both lean controls and those that lost weight through dieting alone [32,33]. Ghrelin, the “hunger hormone”, is a peptide hormone produced by ghrelinergic cells in the gastrointestinal tract which functions as a neuropeptide in the central nervous system. Besides regulating appetite, ghrelin also plays a significant role in regulating the distribution and rate of use of energy [34]. It prepares the body for food intake by acting on hypothalamic brain cells to increase hunger, gastric acid secretion and gastrointestinal motility [35,36]. Ghrelin is secreted when the stomach is empty, but secretion stops when the stomach is stretched. Bariatric surgeries involving excision of the fundus as in vertical sleeve gastrectomy reduce plasma ghrelin levels by about 60% in the long term [37]. However, studies are conflicting as to whether or not ghrelin levels return to nearly normal

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with gastric bypass patients in the long term after weight loss has stabilized [38].

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lowing a meal (late dumping). Dietetic input is crucial and involves reducing amount of carbohydrate in main meals with regular glucose in-between (glucose tablets) [6,39,42].

3.3. Post-prandial sequelae There is a distressing array of new gastrointestinal symptoms (‘post gastrectomy syndrome’) resulting from the loss of reservoir function, denervation, disruption of the pyloric mechanism and the type of reconstruction. Post gastrectomy syndromes include metabolic/nutritional alterations, dumping syndrome, bile reflux gastritis, gastroparesis, afferent/efferent limb syndromes, the Roux syndrome and postvagotomy diarrhoea. About 25% of patients will develop post gastrectomy syndrome but only 1–4% develop severe debilitating symptoms. It is made worse by bad technique. Too extensive a resection predisposes to a high incidence of postprandial symptoms including early dumping that severely limits calorie intake [14,39]. 3.3.1. Early dumping Post gastrectomy complications may occur as vasomotor ‘dumping’ due to rapid gastric evacuation from loss of pyloric regulation and receptive relaxation resulting in a hypertonic load to the small intestine triggering autonomic reflexes and release of vasoactive peptides. Fluid shifts can cause hypotension triggering autonomic catecholamine surge. Multiple gut hormones implicated include serotonin, vasoactive intestinal peptide (VIP), cholecystokinin (CCK), neurotensin, peptide YY, enteroglucagon etc. The rapid filling of proximal small intestine with hypertonic food also leads to rapid movement of fluid into the gut from extracellular space resulting in diarrhoea. The characteristic symptoms of early dumping are epigastric fullness, sweating, faintness and palpitations 30 min after eating and may last for an hour. These can lead to food avoidance with reduced quality of life and malnutrition. It is more troublesome following subtotal gastrectomy or where pylorus is destroyed or bypassed. Dumping symptoms are quite common in the first weeks or months but improve over the months from small bowel adaptation or unconscious modification of diet [40,41]. 1–2% have debilitating symptoms but because of genuine reassurance to the patient, dietary advice to eat small meals, restrict carbohydrate intake and avoid too much fluid less than 1% requires surgical intervention. In many patients there is development of malnutrition, manifested as anaemia and weight; loss in the first few months after operation to a new level which then stays steady [14,41]. As many of the postgastrectomy problems are due to by-pass of the duodenum and loss of gastric capacity, dumping may be diminished by conversion to a Billroth I anastomosis, a Roux-en-Y reconstruction or by interposing a 10–15 cm segment of proximal jejunum aimed at slowing down gastric emptying [14,27]. Unfortunately, the use of gastric pouches or jejunal interpositions has not significantly improved on the results of more standard reconstructions. A particular hazard of jejunal interposition is an increased risk of bile and alkaline reflux with consequent peptic ulceration at the new gastrojejunal junction. The defect of normal peristalsis in the long jejunal limb may also result in voluntary and involuntary regurgitation. And so this operation should only be used in those with severe degree of dumping or small stomach syndrome and a proton pump inhibitor (PPI) given. The beneficial effect of the Roux-en-Y is thought to be due to transection of the neural plexuses that effectively slow gastric emptying in the long jejunal limb [41]. 3.3.2. Reactive hypoglycaemic attacks Complex neurohumoral response produces unpleasant gastrointestinal and cardiovascular symptoms. Rapid carbohydrate absorption stimulates excessive or asynchronous insulin secretion causing a rebound hypoglycaemia, blackouts, and seizures 2–3 h fol-

3.3.3. Diarrhoea Diarrhoea is caused by truncal or inevitable vagotomy, early dumping, and bacterial overgrowth [39,41,42]. The combination of loss of gastric acid and formation of blind loops results in accumulation of aerobic and anaerobic organisms normally found in colon. Faecal bacteria release toxins that destroy brush borders vital to digestion and consume B vitamins. They deconjugate bile acids essential for normal fat absorption in the proximal small intestine. The increased faecal fats result in steatorrhoea and weight loss. Investigation involves 14C glycocholate breath test and treatment includes the antibiotics (metronidazole/neomycin) and probiotics (fresh unpasteurized yoghurt) to inhibit recolonization with and after antibiotics. Relative pancreatic insufficiency may also result in steatorrhoea but once bacterial overgrowth is excluded, it can be treated with pancreatic enzyme supplementation (Creon). Post vagotomy diarrhoea is due to vagal denervation leading to intestinal dysmotility, rapid gastric emptying of liquids, hypoacidity, malabsorption of bile acids and bacterial overgrowth in the proximal bowel. Severe form of post vagotomy diarrhoea may have 10–20 episodes per day, often explosive with no temporal relationship with food and occurring at all times even during sleep. It is associated with malnutrition, weight loss, and weakness [6,42]. 1% of post vagotomy diarrhoea are refractory to medical treatment (dietary modifications, bile chelator (cholestyramine), oral neomycin, antidiarrhoeal agents) and severe enough for surgical intervention. The antiperistaltic jejunal interposition 75–100 cm from the ligament of Treitz or the Cuschieri reversed distal ileal onlay graft gives relief for the majority [43], 3.3.4. Bilious vomiting Bile reflux gastritis is more common after Billroth II gastrectomy and less with Roux-en-Y procedure. It commonly occurs after gastric reconstruction with debilitating symptoms in 1–2%. The symptoms of alkaline bile reflux are epigastric discomfort, heartburn, and vomiting. Persistent reflux can lead to stricturing and dysphagia [43,44]. It would be diagnosed by upper gastrointestinal endoscopy and Tech 99M HIDA scanning. Gastric emptying study would rule out gastroparesis [44,45]. Medical management with PPIs and H2 blockers is rarely helpful thus requiring revisional surgery. Biliary diversion is used most often for severe bilious vomiting or if symptoms are unremitting as treatment options are limited and only often successful. A simple version is jejuno-jejunostomy between the afferent and efferent limbs of a gastrojejunostomy (Uddin loop) where the former is quite long. An alternative common variety is a subtotal (80%) gastrectomy with Roux-en-Y reconstruction with the efferent loop some 40–50 cm distal to the stoma or lengthening of Roux loop which gives 80% relief [46]. Again proton pump inhibition would reduce the risk of gastrojejunal ulceration [14]. Gastro-oesophageal reflux disease (GORD) is more prevalent as body mass index (BMI) increases. There is reduced long-term effectiveness of anti-reflux (Nissen fundoplication) procedure in obese patients (BMI >30). Laparoscopic Roux-en-Y gastric bypass is the most effective and recommended option as it treats GORD, reduces weight, and improves comorbidities [47]. Likewise, bile reflux following gastric bypass for morbid obesity will benefit from the very effective and much simpler anti-reflux (laparoscopic Nissen fundoplication) procedure than revision surgery [48]. Gastroparesis is delayed gastric emptying in the absence of mechanical obstruction. It is the most common (50%) of the post gastrectomy syndromes especially with associated truncal vagotomy, and, generally inversely proportional to the extent of gastric resection [49,50]. The patient is unable to tolerate diet 7–14 days

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343 after surgery but the vast majority improves with time or with 344 Q3 prokinetic agents. Other causes metabolic (electrolyte, endocrine, 345 medications), mechanical (stoma oedema, small leaks, adhesions, 346 kinking, haematoma, intussusception, stricture) should be ruled out. Sometimes surgery is required with the original operation dictat347 ing the corrective procedure, i.e. further resection following a partial 348 resection. Most advocate R-Y reconstruction and completion va349 gotomy [51] . 350 351 3.3.5. Afferent/efferent loop syndromes 352 Afferent loop syndrome is a mechanical problem with partial ob353 struction of the afferent limb from kinking, angulation, stenosis or 354 adhesions. The afferent limb being almost always 30–40 cm or longer 355 is a predisposing factor and always occurs with a Billroth II bypass. 356 Treatment is always surgical. It entails either revision of Billroth II, 357 conversion of Billroth II to Billroth I, conversion of a Billroth II to 358 R-Y with a long Roux limb and complete vagotomy to prevent mar359 ginal ulcer or fashioning an entero-enterostomy below the stoma 360 if adhesions are present [30]. The Chronic type is more common. 361 The severe post prandial pain, bile and pancreatic secretions build 362 up in the afferent limb until the intraluminal pressure overcomes 363 the obstruction resulting in projectile bilious vomiting with im364 mediate relief of pain. The efferent loop syndrome is less common 365 and difficult to distinguish from afferent loop syndrome or bile reflux 366 gastritis. It is usually due to adhesions or an internal hernia of the 367 limb behind the gastrojejunal anastomosis and treatment is always 368 surgical. 369 370 3.3.6. The Roux syndrome 371 The Roux syndrome is a complex of symptoms including post 372 prandial epigastric fullness, nausea, intermittent vomiting and often 373 weight loss. It is thought to be the result of an atonic roux limb that 374 impedes gastric emptying. Studies have demonstrated that it is a 375 result of loss of the duodenal pacesetter potentials which are fastest 376 in the duodenum and spread distally to the terminal ileum. The fre377 quency is decreased when the jejunum is resected and ectopic 378 pacemakers spread retrogradely to the stomach. It is thus com379 moner with a large gastric remnant and after truncal vagotomy. 380 Treatment is with a trial of prokinetic agents or aggressive gastric 381 resection with R-Y reconstruction [52]. 382 383 4. Nutritional problems 384 385 Malnutrition following gastric bypass is usually due to failure 386 to ingest sufficient calories especially in total gastrectomy pa387 tients. Malabsorption is a rare cause of malnutrition in non388 bariatric gastric bypass surgery. Carbohydrate absorption is usually 389 satisfactory but protein and particularly fat absorption is reduced 390 resulting in weight loss. Close dietetic follow-up should ensue after 391 bacterial overgrowth, early satiety, dumping, and relative pancre392 atic insufficiency have been excluded. 393 394 4.1. Vitamin B12 deficiency and macrocytic anaemia 395 396 As vitamin B12 is bound to intrinsic factor secreted by the pari397 etal cells in the body and fundus of the stomach and absorbed in 398 the terminal ileum, there is virtually no absorption of B12 post gas399 trectomy. B12 deficiency is always seen following total gastrectomy 400 and in about 50% of those patients who undergo partial gastrec401 tomy. Methyl-methionine testing is more accurate than serum B12 402 in the presence of proton pump inhibitor use. Vitamin B12 deficien403 cy usually takes some years to develop because of the large body 404 stores of the vitamin [6,42]. All gastrectomy patients require 405 3-monthly hydroxocobalamin injections. The stagnant loop syn406 drome which arises as a consequence of anatomical abnormalities 407 of the small intestine including blind loops results in bacteria over408

growth in the jejunum. The effects are complex, but malabsorption of fat, vitamin B12 and other B vitamins is usually present. A course of broad-spectrum antibiotics will usually temporarily restore vitamin B12 absorption to normal, but complete cure may require revisional surgery [6,14,53]. Patients should be supplemented with vitamin B during and after treatment. Vitamin D malabsorption results in osteomalacia especially in post-menopausal women. Thus all patients >70 years would receive calcium supplements and undergo 5-yearly assessments for metabolic bone disease. 4.2. Iron deficiency anaemia Iron deficiency anaemia is present in 40–50% of patients following partial gastrectomy [42]. In addition to impaired dietary intake, achlorhydria is associated with impaired absorption of iron in the duodenum and jejunum as reduced ferrous (Fe2) rather than food ferric (Fe3) ion is absorbable. Iron malabsorption is not normally an issue unless vegetarian, as small intestine takes over absorption. Iron and vitamin C supplements should be considered for the first post-operative year [42,53]. 5. Gastric cancer The risk of Gastric malignancy in the remnant stomach is increased about 4-fold. The exact mechanism is unclear, but achlorhydria, atrophic gastritis, persistent bile reflux, denervation of the gastric mucosa and bacterial invasion of the gastric stump have been regarded as possible aetiologies [54,55]. The gastric mucosa of the patients who underwent gastric surgery for malignancy tends to develop recurrent cancer, less than 10 years after surgery at the anastomosis site and new cancers at the nonanastomosis site. Those patients with initially benign disease may develop cancer but more than 10 years after at the anastomosis site [56]. By attenuating the chronic gastritis–metaplasia–dysplasia– carcinoma sequence, there is a role for H. pylori eradication therapy in preventing anastomotic recurrence or a new primary [27,56]. 6. Bariatric surgical procedures that involve gastric bypass Morbid obesity defined as a body mass twice ‘ideal’ (Body mass index >39 kg/m2) has a high health risk and excess mortality [7]. The National Institute of health and Clinical Evaluation (NICE) guidelines (2006) recommend bariatric surgery as a treatment option for people with morbid obesity (BMI >40 kg/m2) or who have lower BMI (35 kg/m2) plus other significant disease such as type 2 diabetes mellitus and hypertension that could improve if they lost weight. Because of the risks, surgery is only offered when all appropriate nonsurgical measures are unsuccessful [8]. Several variations of Billroth II gastrectomy as a form of biliopancreatic bypass have been described and not surprisingly the more complex operations are associated with a higher incidence of morbidity [9]. The most commonly performed procedure is the Roux-en-Y gastric bypass (RYGB) [10]. Biliopancreatic diversion (BPD), with or without duodenal switch (BPD-DS), is less commonly performed but is often considered in extremely obese individuals [11]. All procedures can be performed laparoscopically with a lower rate of complications such as wound infection and incisional hernias [57,58]. 6.1. Roux-en-Y gastric bypass (RYGB) RYGB is a combination of both restriction and malabsorption. The creation of a small stomach pouch leads to early satiety combined with the bypassing of the stomach, duodenum and up to 200 cm of jejunum leading to malabsorption. Release of distal gut hormones and changes in taste also have a role in the mechanism of action. Technically, the stomach is divided (stapled) into an upper

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Fig. 2. Diagram of Roux-en-Y gastric bypass.

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gastric pouch, which is 15–30 ml in volume, and a lower gastric remnant. The gastric pouch is anastomosed to the jejunum after it has been divided some 30–75 cm distal to the ligament of Treitz; this distal part is brought up as a ‘Roux-limb’. The excluded biliary limb, including the gastric remnant, is connected to the bowel some 75–150 cm distal to the gastrojejunostomy (Fig. 2) [53]. The small size of the upper gastric pouch is so reduced that it “restricts” or limits the amount of food intake. It also provides satiety with smaller portions of food. The lower gastric remnant no longer receives, stores, and mixes food but remains secretory. The malabsorptive element in gastric bypass is achieved as a result of the Roux-en-Y formation “bypassing” the upper part of the intestine. The length of the Roux-en-Y limb was determined by the patient’s BMI; 100 cm for those with a BMI of up to 48 kg/m2 and 150 cm for patients with a higher BMI. This surgery can result in two-thirds of excess weight loss within 2 years, albeit, with specific nutritional deficiencies requiring replacement [8–10,53]. The complication rates are about 10% in expert centres [10]. The main technical problem after gastric bypass is anastomotic leakage, which in large series may reach 5% [5]. It is a feared early complication appearing most commonly at the gastrojejunostomy in RYGB with the incidence associated mortality of 0.1% [53,58,59]. Higher BMI, male gender, re-operation, older age and surgeon’s experience are associated with higher anastomotic leakage rates [60,61]. 6.2. Omega loop mini gastric bypass (MGBP) MGBP is being promoted as a quick and effective alternative to the standard Roux-en-Y gastric bypass procedure. It works both by restricting food intake at any one time, and by altering gut hormones involved in appetite control. It seems more efficient on weight loss (70–80% at 2 years) and co-morbidities than the RYGBP, with the advantage of being less technically difficult and less morbid, especially for multi-complicated obese and/or the super obese. There is immediate improvement of diabetes, with some patients coming off insulin within a few days post-surgery [62]. It consists of a unique gastro-jejunal anastomosis between a long gastric pouch (restrictive part) and a jejunal omega loop of 150–200 cm (malabsorptive part) (Fig. 3). In effect, therefore, about 2 m of small bowel has been bypassed before absorption of food (and calories) can take place. Fewer calories absorbed means weight loss. It is clear that in the case of the MGBP there is only one anastomosis, whereas in the RYGBP there are two – an upper and a lower. Because of this the MGBP can be done in less time than the RYGBP and – at least theoretically – with fewer early complications. However, this procedure could be at risk of biliary reflux and anastomotic ulcers with dys-

Fig. 3. Omega loop mini gastric bypass.

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plastic changes of the gastric and oesophageal mucosa. As a result, MGBP remains a controversial subject, particularly as only one monocentric randomized trial has compared it to the RYGBP, which remains the gold standard [62].

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6.3. Biliopancreatic diversion Bilio-pancreatic diversion (BPD) is a combination of being initially restrictive but ultimately malabsorptive. Technically, BPD involves a distal gastrectomy leaving a proximal stomach volume of 150– 400 ml. Depending on the BMI the ileum is divided 260–360 cm proximal to the ileocecal valve, and the alimentary limb is connected to the gastric pouch to create a Roux-en-Y gastroenterostomy. An anastomosis is performed between the excluded biliopancreatic limb and the alimentary limb 60 cm proximal to the terminal ileum (Fig. 4). There is 1.1% 30 day mortality and a predicted 70–80% weight loss at 2 years [11,63]. Bilio-pancreatic diversion with duodenal switch (BPD-DS) is mildly restrictive and mainly malabsorptive. It is technically a modification of the BDS incorporating a sleeve gastrectomy and a longer common limb. In BPD-DS, a vertical sleeve gastrectomy (SG) is constructed and the duodenum is divided 4 cm distal to the pylorus. The small bowel is divided at mid-point and the distal small bowel (alimentary limb) is anastomosed to the duodenum. The iliopancreatic limb (proximal small bowel) is anastomosed to the ileum 100 cm proximal to the terminal ileum (Fig. 5) [64]. There is a predicted 75–80% excess weight loss at 2 years especially as the excision of the fundus in the sleeve gastrectomy would decrease circulating Ghrelin and reduce appetite [63]. However, the outcome of sleeve gastrectomy when used primarily is the same as gastric bypass [61,63]. In BPD-DS, leakage from the staple line is more common than anastomotic leakage and the total enteric leakage rate is 5% [65]. Dumping syndrome and anastomotic ulcers are less likely as

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Fig. 4. Diagram of biliopancreatic diversion.

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Fig. 6. (a, b) Single anastomosis duodeno-ileal anastomosis (SADI) procedure.

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excess weight loss 5 years after SADI procedure remains comparable to the DS at 90% (compared with 50–70% for the sleeve or bypass) [67]. 560

Fig. 5. Diagram of biliopancreatic diversion with duodenal switch.

7. Complications

561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581

compared to a BPD procedure because of the preservation of the pylorus in BPD-DS [65]. 6.4. Single anastomosis duodeno-ileostomy (SADI) 10–20% of patients have a sub-optimal result following bypass or sleeve surgery. BPD-DS is quite a significant malabsorptive procedure as there is usually only 1 m of ‘common’ limb of small bowel. The extra weight loss in BPD-DS is offset by a significant risk of protein or vitamin deficiency unless they are assiduous with their diet, and a poorer quality of life from diarrhoea (6–8 times per day). Single-anastomosis duodeno-ileal bypass with sleeve gastrectomy is a simplification of the duodenal switch that may behave as a standard biliopancreatic diversion but easier and quicker to perform. Given its effectiveness as a primary surgery it is hypothesized that it would be successful as a second-step operation. The anastomosis between the duodenum and the small bowel is central to the procedure, and with a ‘common limb’ of small bowel measuring 3 m long the increased bowel frequency is much less compared to BPD-DS (Fig. 6a,b) [66]. Initial reports suggest that the

Patient education, thorough pre-operative work-up and regular follow-up avoid most complications of bariatric surgery. The surgeryrelated complications are the usual complications of gastrointestinal surgical procedures and are managed similarly. These include haemorrhage, anastomotic leak, and anastomotic strictures [68–70]. The complications general to any abdominal operation include pneumonia, deep vein thrombosis, urinary retention and ileus. Small bowel motility returns within a few hours and gastric and colonic motility after a few days, depending on the degree of surgical trauma [7–9]. 7.1. Management of side-effects of bariatric surgery The early unfavourable side effects of the bariatric gastric bypass surgery are dehydration and constipation, and the dumping syndrome. Dehydration and constipation is a common problem and patients must get used to drinking on a regular basis aiming for 1.5– 2 l/day. Re-education and occasional laxatives are advised. Almost 85 percent of patients who have gastric bypass (bariatric) surgery will experience the ‘dumping syndrome’ but surgical revision is a

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last resort [7–9]. Dumping syndrome requires re-education of patient with avoidance of precipitating food stuffs. Highly restrictive gastric pouch patients are advised to eat low volume meals frequently up to 6 times a day and avoid a carbohydrate load which can lead to dumping [71]. Although the parietal cell mass is small, stoma ulceration remains a problem. Anastomotic ulcers are usually late complications of bariatric surgery and occur in 2% of patients within the first post-operative year, and then in 0.5% for up to five years [72]. They are common in smokers and patients who are H. pylori positive. Such ulceration may respond to proton pump inhibition but revisional surgery may be required if the ulcer is resistant. Serum gastrin levels may become excessive and the excluded stomach may require resection [60,61]. A fistula between the pouch and the reQ4 maining stomach must be excluded [71].

7

operative period [76,77]. Although the laparoscopic approach may result in higher rates, closure of potential defects at time of primary surgery is not, however, universal. Standardization of the procedures and new surgical techniques where the mesentery windows are surgically closed may reduce the rate to as low as 1% [77]. Incisional hernias can occur but are less common with the increased use of laparoscopic techniques [58,59]. The risk of additional surgery for symptomatic gallstones from the inadvertent vagotomy is prevented by a prophylactic cholecystectomy during the bariatric gastric bypass procedures [7–11]. Hypersideroblastosis is an uncommon problem due to hyperplasia of the B cells of the pancreas as a result of excessive weight loss giving rise to chronic hypoglycaemia. Pancreatic resection may be required [71]. 8. Revision gastric bypass (bariatric) surgery

7.2. Nutritional and vitamin deficiencies Nutritional and vitamin deficiencies are late complications and patient compliance is the major cause of such problems. BPD and BPD-DS would initially require a post-operative diet high in protein (60–80 mg) [42,73]. Vitamin supplementation on a daily basis is essential and a B12 injection at maintenance dose usually suffices [73]. Internal hernias may easily develop after laparoscopic gastric bypass in which small mesenteric defects (transverse mesocolon, enteroenterostomy or behind the Roux limb) can be created and there are fewer adhesions to tether small bowel loops and prevent them from herniating [74]. In addition patients who have greater degree of weight loss after laparoscopic Roux-en-Y gastric bypass may be more prone to internal hernia because of loss of the protective spaceoccupying effect of mesenteric fat [75]. The reported frequency ranges from 0.4% to 5.5% in RYGB [76]. Long-term data over seven years record a hernia rate of 38% in BPD/BPD-DS [77]. High index of suspicion is required in all patients with abdominal pain with or without small bowel obstruction. Delayed diagnosis may lead to lifethreatening complications of strangulation in the early or late post-

As the number of primary bariatric procedures increases so does the rate of re-operations as a consequence of either a failed primary procedure or complication. It is important to evaluate whether the cause is a technical failure or due to poor patient compliance. Discussion at the bariatric MDT is important in managing such patients with re-referral to both dietetics and psychology. Redo bariatric surgery is associated with a higher mortality (2%) and morbidity (13% leak rate) compared with the primary operation [71]. Anatomical assessment includes plain radiography, contrast swallows, and contrast follow-through studies for a ‘road map’ of the surgically altered anatomy of the upper GI tract. Endoscopy is a useful adjunct in looking at anastomotic strictures, ulcers and assessing pouch sizes. Blood tests are needed for a full haematological and biochemical profile including trace elements and vitamin D. The revisional surgical approaches may include reversal of the obsolete jejunal–ileal bypass (high incidence of malabsorption), reversal/ revision of Roux-en-Y gastric bypass and BPD/switch for malabsorption, removal of eroded pre-anastomotic rings in Rouxen-Y bypass pouches (e.g. Fobi ring) and revision of gastric pouches,

645 646 647

Q11

Table 1 Summary of gastric bypass procedures.

648 649

Procedure

Principle of action

650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678

Billroth II gastrectomy

Non- primary bariatric (restrictive)

Malabsorptive/bypassed limb

Mean excess weight loss

30-day Side effects mortality (%)

50–70% at 2 yrs

0.5

60–80% at 2 yrs Roux-en-Y gastroduodenal Primary bariatric (restrictive Gastric pouch (15–30 ml) bypass 100 cm jejunum (BMI <48 kg/ and malabsorptive) 2 m ) 150 cm jejunum (BMI >48 kg/ m2) Omega loop mini gastric Primary bariatric (restrictive Long gastric pouch (restrictive 70–80% at 2 yrs bypass (MGBP) part), jejunal omega loop of and malabsorptive) 150–200 cm (malabsorptive part) Bilio-pancreatic diversion Primary bariatric (restrictive Gastric pouch (150–400 ml) 70–80% at 2 yrs (BPD) and malabsorptive) Absorptive ‘common’ limb (60 cm proximal to terminal ileum)

0.1

Bilio-pancreatic diversion with duodenal switch (BPD-DS)

Primary bariatric (mildly restrictive and mainly malabsorptive)

1.1

Single anastomosis duodeno-ileostomy (SADI)

Primary bariatric (restrictive Duodeno-ileal bypass ‘common’ limb 3 m and significantly malabsorptive)

Sleeve gastrectomy Absorptive ‘common’ limb (100 cm proximal to terminal ileum)

75–80% at 2 yrs

75–80% at 2 yrs, 90% at 5 yrs

0.1

1.1

Bile reflux gastritis, stomal ulcers, dumping syndrome Diarrhoea Mild B12 deficiency Iron deficiency anaemia Dehydration and constipation, dumping syndrome, anastomotic ulcers, nutrition and vitamin (B12, D) deficiencies, internal hernias Biliary reflux, anastomotic ulcer, dysplasia

Dumping syndrome, anastomotic ulcers, vitamin deficiency, bone demineralization, protein deficiency, diarrhoea, foul smelling stool, anaemia, internal hernias more frequent Similar to BPD but less dumping syndrome and anastomotic ulcers, severe protein deficiency Diarrhoea (8×/day) Less diarrhoea than BPD-DS, protein deficiency

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gastrojejunostomies, jejunal-jejunostomies, remnant gastrectomies for enlargements, strictures, and gastrogastric fistulae, respectively [53,78,79]. These revision procedures carry with them a higher risk of complication than the original procedure, revisions must be performed by experienced surgeons.

719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747

9. Outcome of bariatric surgery Metabolic (bariatric) surgery results in better glucose control than medical therapy and overwhelmingly leads to disease remission [7–10]. Results at 2 years showed DM remission of 0% in a medical cohort, 75% in the gastric bypass group and 95% for the biliopancreatic diversion group [78]. Operative intervention is more effective than conservative measures at present in treatment of obesity, resolution of co-morbidities and cost effectiveness. At 1 year the mean total % weight loss from all surgical approaches is 20– 21.6% and 1.4–5.5% from non-surgical approaches. At 2 years there is 16–28% weight loss following surgery but weight gain of 0.1– 0.5% with non-surgical approaches [80]. For people with very high BMI, BPD-DS resulted in greater weight loss with sustainability than RYGB (Table 1) [9]. The Swedish obesity study demonstrated maintenance of weight loss at 10 years following surgery with weight gain in the non-surgical arm. A 40% reduction of death over a 7 year period and a decrease in ischaemic heart disease of 56% were reported. There were no differences in weight loss between the open and the laparoscopic approach [81]. Across all studies adverse event and reoperation rates were generally poorly reported. Most trials followed participants for only one or two years, and therefore the long-term effects of surgery may remain unclear [82]. However, the assessment of outcome is not simply based on clinical effectiveness but also on the cost effectiveness which includes savings from correction of hypertension, improved cardiac status, resolution or amelioration of diabetes mellitus and respiratory function and gainful employment [83,84].

748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 Q5

10. Conclusions The weight-related side-effect of gastric bypass surgery for benign or malignant disease has inadvertently pioneered primary metabolic (bariatric) surgery. Because metabolic (bariatric) surgery may have serious side effects and complications, the long-term health benefits must be considered and found greater than the risks for the individual patient. Post gastrectomy side effects are few after Roux-en-Y gastric bypass but more are seen after Billroth II bypass procedures thus requiring conversion to a Roux-en-Y. Bile reflux gastritis and gastroparesis are the most common post gastrectomy complications. Close multidisciplinary follow-up with surgeons, specialist nurse, and dieticians is crucial following gastric bypass surgery to optimize both physical and psychological quality of life.

763 764 765 766

Conflict of interest statement None.

767 768 Q12 Uncited references 769 [85], [86] 770 771 Appendix: Supplementary material 772 773 Supplementary data to this article can be found online at 774 775 Q6 doi:10.1016/j.ijso.2016.09.004.

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