Bariatric surgery: techniques, outcomes and complications

1. Introduction 

Obesity is currently a major healthcare concern in the Western world, and is also increasingly affecting the populations of the developing world. The World Health Organisation (WHO) estimates that 1 billion people in the world are currently overweight (BMI 25–30kg/m2) and another 300 million to be obese (BMI ≥30kg/m2). Morbid obesity is defined as a BMI ≥40kg/m2.

Obesity has a well-known association with coronary heart disease (CHD), hypertension, diabetes mellitus (DM), dyslipidaemia, obstructive sleep apnoea (OSA) and cancer. The relationship of central obesity with the Metabolic Syndrome (Syndrome X) is recognised and well described. Patients seen in bariatric surgery clinics not only have Type II DM, hyperfibrinogenaemia and dyslipidaemia but may also have non-alcoholic steatotic hepatitis (NASH) which may progress to cirrhosis. Morbid obesity is also associated with polycystic ovary syndrome (PCOS) and hence subfertility. The raised intra-abdominal pressure associated with being morbidly obese may also contribute to gastro-oesophageal reflux disease (GORD), genuine stress incontinence (GSI) and venous stasis.

The 2002 WHO report attributes 58% of cases of Type II DM, 21% of cases of CHD and up to 42% of certain cancers to the obesity epidemic.1 In the United States, 20% of the population are obese and it is estimated that $140 billion per annum is directed to managing obesity-related disease. Obesity is also increasingly affecting the adolescent population. Studies looking at long-term follow-up (>50 years) of these patients have shown an increased incidence of both cardiac and cerebrovascular disease, as well as an increase in colorectal cancer mortality.

Drug therapy along with various diet and exercise programmes targeted at reducing obesity, have not proved effective in achieving long-term weight reduction. Medical therapy is associated with only 10% weight loss and is limited not only by poor efficacy but also by drug side effects. These medications include the serotonin noradrenaline re-uptake inhibitor, Sibutramine (Reductil) which reduces appetite and the pancreatic lipase inhibitor, Orlistat (Xenical), which inhibits 30% of fat absorption resulting in oily stools and fat-soluble vitamin deficiencies.2, 3, 4 Rimonabant (Acomplia), an anorectic obesity drug that works by selective blockade of the cannabinoid receptor (CB-1), has been suspended from the UK market since October 2008, amid concerns over exacerbation of depression and increased suicide risk.5

Bariatric (obesity) surgery refers to the variety of surgical procedures employed for achieving weight loss. It involves modification of the gastrointestinal tract to either reduce volume and/or absorptive capacity. Bariatric surgery also affords dramatic long-term improvement or complete remission of any existing co-morbidity with a decrease in onset of new co-morbidity.6, 7 Bariatric surgery has been shown in the Swedish Obesity Surgery (SOS) trial to improve quality of life and to decrease mortality compared to non-surgical controls.8

In 2007 in the USA, over 240,000 bariatric surgeries were performed compared to 18,000 in 1994. In the UK we are mirroring the obesity epidemic in the US and hence the increasing availability of bariatric surgery services. Indeed, it has been estimated that England will have the third highest rate of obesity by 2025 with over 50% of the population having a BMI >30kg/m2.9 Consequently, there is a need that as the obesity epidemic continues, surgeons acquire the necessary advanced laparoscopic skills to perform bariatric surgery and meticulous attention be paid to the pre-operative and post-operative care of the bariatric patient. Also, there is an increased need for dedicated health professionals such as anaesthestists to develop a specialist interest in bariatric surgery. In this article, we aim to describe the commonly performed bariatric procedures in terms of basic surgical technique, reported outcomes and complications.

2. Indications and contra-indications 

The currently accepted indications for bariatric surgery in the UK, as recommended by the National Institute for Clinical Excellence (NICE), are based on the US 1991 National Institutes of Health (NIH) Consensus Statement.10 Bariatric surgery should be offered to patients with a BMI ≥40kg/m2 alone or ≥35kg/m2 if associated with serious co-morbid conditions such as DM, OSA or CHD, when 6 months of medical treatment or lifestyle change have failed to produce and sustain adequate weight loss. Surgery may be proposed in the first instance if patients are super-obese (BMI ≥50kg/m2). The surgery should be performed in specialist centres by experienced surgeons in multi-disciplinary clinical settings. Pre-operative as well as comprehensive post-operative management with lifelong medical surveillance should be available. Contra-indications to bariatric surgery include patients considered very high or unacceptable anaesthetic risk, untreated major depression or psychoses, alcohol or drug abuse, advanced liver disease or inability to comply with post-operative medical, nutritional and psychological assessments. Age per se is not a contra-indication to surgery with evidence for good outcomes in patients over 60 years of age.11

3. Bariatric surgical procedures 

The field of bariatric surgery has developed quickly over the last 30 years with the laparoscopic technique evolving since the mid-1990s. The rationale for the laparoscopic approach exists as for other forms of surgery. There is a decreased incidence of post-operative wound infection, dehiscence and incisional hernia, reduced blood loss, faster recovery to daily activities and reduced hospital stay compared to the equivalent open procedure.12

Bariatric surgical techniques can be divided into restrictive, malabsorptive or combined restrictive/malabsorptive procedures.

Restrictive procedures include

Malabsorptive procedures include

The laparoscopic Roux-en-Y gastric bypass (LRYGB) is considered a combination of both restriction and mild mal-absorption.

The choice of procedure for any given patient is made on an individual basis, and relates to patient BMI and desired excess weight loss (EWL), eating behaviour, co-morbidities and previous surgical history.

Thorough pre-operative preparation of the morbidly obese patient by the MDT is essential to achieve good outcomes from bariatric surgery. Co-morbid conditions such as hypertension, DM, OSA must be optimised prior to surgery. Further information on pre-operative assessment and work-up can be found in the article by O'Neill and Allam.13 Prior to surgery, patients may be assessed by a clinical psychologist and may require counselling, in addition to education on diet alteration and advice to stop smoking. Venous thrombo-embolism (VTE) accounts for the majority of deaths in patients undergoing bariatric surgery hence the importance of intermittent pneumatic compression stockings peri-operatively and prophylactic low molecular weight heparins (e.g. enoxaparin 40mg SC bd) which should be continued for 2–4 weeks post-operatively depending on individual VTE risk. Patients must be prepared for frequent clinic follow-up, band adjustments in the case of LAGB surgery, the need for long-term vitamin and/or mineral supplementation (for LRYGB, BPD and BPD-DS patients), an alteration in eating habits and the possible need for re-operation.

4. Laparoscopic adjustable gastric band insertion 

The laparoscopic adjustable gastric band (LABG) has now superseded the VBG (also known as the Mason procedure or ‘stomach stapling’) as the favoured restrictive bariatric surgical technique. The LAGB is currently the most commonly performed bariatric procedure in Europe and Australia.

The gastric band is an implantable device made up of 2 parts; a round silicone band with an inflatable cuff that sits around the cardia and a reservoir that is placed over the fascia of the abdominal wall (Fig. 1). The components are connected by silicone tubing, to allow addition or removal of saline via the subcutaneous reservoir to adjust the cuff size and therefore the degree of gastric restriction.

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Fig. 1 Diagram of adjustable gastric band in situ.

Anatomically, the gastric band is placed just below the gastro-oesophageal junction (GOJ) around the gastric cardia, creating a 10–15ml gastric pouch. The band forms a stoma of about 12mm in diameter and works by reducing the rate of food entry, with stretching of the stomach wall leading to early satiety through signals transmitted via the nucleus tractus solitarius to the appetite centres in the hypothalamus thus reducing appetite. Maintenance of satiety is thought to be dependent on maintenance of the 15ml gastric pouch and stoma restriction. The LAGB is fully reversible, as there is no anatomical alteration to the bowel. Average operating time is 45–60min and it may be performed as a day case but usually involves overnight hospital stay. Most patients can return to work within 3–5 days.

5. Laparoscopic Roux-en-Y gastric bypass 

Over the past 10 years in the USA, the laparoscopic Roux-en-Y gastric bypass (LRYGB) has been considered the gold standard technique and is the most commonly performed bariatric operation. This is primarily due to its good long-term history for weight loss with minimal nutritional deficit. The procedure achieves weight loss by restricting food intake by reducing the size of the stomach and also by mild reduction of food absorption. In addition, the gut rearrangement achieved in this procedure induces significant changes in the production of several gastrointestinal hormones. The levels of ghrelin, a hormone primarily secreted by neuroendocrine cells of the gastric fundus and which acts on the hypothalamus to regulate appetite, are suppressed after LRYGB.25 Many studies have shown that Glucagon-like peptide-1 (GLP-1), Peptide YY (PYY) and Glucose-Dependent Insulinotropic Peptide (GIP) levels increase following LRYGB and could contribute to the observed weight loss, early resolution of type 2 DM and satiety.26 It has been proposed that changes in vagal control as a result of the gastric bypass, result in lowering of ghrelin levels providing a further mechanism to explain weight loss.

The first open gastric bypass operation was performed in 1969 by. Dr. Edward Mason.27 The operation originally involved a jejunal loop gastric bypass and a larger, horizontally orientated gastric pouch. Following a high incidence of bile reflux, this procedure has been somewhat modified over the years. Rather than a loop bypass, Roux-en-Y gastric bypass is now favoured in association with a smaller, divided and vertically orientated gastric pouch.28 The distal small bowel is anastomosed to the gastric pouch (alimentary limb) and the proximal small bowel (bilio-pancreatic limb) is re-attached more distally to produce a Y-shaped configuration. A significant change occurred in the mid-1990s when Dr. Alan Wittgrove performed the operation laparoscopically.29 Today, bariatric centres are increasingly performing this procedure laparoscopically.

5.1. Surgical technique 

There is wide inter-surgical variation seen with this technique, and the operating sequence often depends on surgical preference. However, there are a number of fundamental steps involved in the Roux-en-Y gastric bypass and these can be described as follows:

i)Port placement

ii)Creation of Roux limb and jejuno-jejunostomy

iii)Gastric pouch creation (15–20ml)

iv)Formation of the gastro-jejunostomy

v)Closure of mesenteric defects

The patient is positioned in the supine position with legs strapped together and often, steep reverse Trendelenburg position is employed at intervals during the procedure. After appropriate port placement, the greater omentum is displaced anteriorly and up towards the stomach and the small bowel followed proximally to expose the ligament of Treitz. At 15–50cm distally from this point, the jejunum is divided and this proximal part of the small bowel forms the bilio-pancreatic limb. Once the jejunum is divided, the alimentary or Roux limb is measured to the desired length (75–150cm). At this point, and following enterotomies in both limbs, the Roux limb is anastomosed to the bilio-pancreatic limb to form the jejuno-jejunostomy. The enterotomy defect is closed. The selected Roux limb length varies depending on surgical preference, patient BMI and required weight loss. Usually a Roux limb length of 75–100cm is adopted for patients with BMI <50kg/m2 while a length ≥150cm is recommended when BMI ≥50kg/m2. There is evidence that longer Roux limb lengths (≥150cm) in patients with BMI >50kg/m2 increase weight loss without an increase in nutritional deficit.30 The mesenteric defect created after performing the jejuno-jejunostomy is always closed as there is a risk of internal herniation. A linear stapler is applied in sequence to create a 15–20ml proximal gastric pouch. The distal stomach although now functionally separate, remains in situ. The Roux limb may then be advanced ante- or retro-colic and ante- or retro-gastric, depending on surgical preference. Most commonly, the ante-colic, ante-gastric approach is favoured as it is technically easier, but requires division of the greater omentum to allow the Roux limb to be brought up in front of the transverse colon and anastomosed to the gastric pouch without undue tension. If there is a concern over tension at the gastro-jejunal anastomosis, the retro-colic, retro-gastric approach should be considered as it requires a shorter distance for the Roux limb to be brought up to the gastric pouch. Indeed retro-colic, retro-gastric placement of the Roux limb requires a defect in the transverse mesocolon to be created allowing passage of it into the retro-gastric space. The major disadvantage is the creation of an extra defect, which may predispose to internal herniation of small bowel. The mesocolic defect must then be closed.

The gastro-jejunostomy may be created with either circular or linear staplers or handsewn depending on surgical preference.

Fig. 2 shows the typical appearance of a Roux-en-Y gastric bypass reconstruction. Alternative techniques of forming the gastro-jejunostomy include a per-oral technique using an anvil attached to an oro-gastric tube which is passed through the posterior wall of the gastric pouch allowing for anastomosis with the circular stapling gun introduced transabdominally.

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

Meticulous post-operative care of the patient undergoing LRYGB is as essential as the pre-operative and intra-operative care. Patients are usually nursed in a specialised bariatric ward and sometimes admitted to a High Dependency setting for the first 24h post-operatively. Close attention is placed on observations of vital signs especially a tachycardia >120bpm which in the first 24h may indicate intra-abdominal bleeding or technical anastomotic failure. Close observations of respiratory status is vital as this group of patients are prone to developing respiratory failure secondary to basal atelectasis or inadequate post-operative analgesia restricting inspiration. Patients suffering from OSA might need CPAP or BiPAP ventilatory support. Pre-operative and post-operative subcutaneous prophylactic enoxaparin are given. Intermittent pneumatic compression stockings are also continued for the duration of the patient's hospital stay to further reduce the risk of DVT and PE. An upper GI series is performed routinely by many units the next day to rule out a technical leak at the gastro-jejunostomy or jejuno-jejunostomy anastomoses. If this is satisfactory, the patient is commenced on a clear liquid diet for 1 week and is usually discharged on post-operative day 2 or 3. Simultaneous surgical and dietetic follow-up usually occurs 2 weeks post-surgery.

6. Laparoscopic biliopancreatic diversion and duodenal switch 

The bilio-pancreatic diversion and duodenal switch (BPD-DS) is a complex procedure, which has evolved over the last 30 years. Initially, Scopinaro in 1976 devised the BPD which consisted of a distal gastrectomy and formation of a gastro-ileostomy utilising the distal 250cm of ileum as shown in Fig. 3.

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Fig. 3 Diagram of bilio-pancreatic diversion.

The bilio-pancreatic limb was anastomosed to the final part of the ileum, at a distance of 50cm from the ileocaecal valve. This produced a 50cm common channel, significantly reducing food absorption.44 Although highly successful in terms of % EWL (78% at 5 years follow-up) the procedure resulted in a high rate of protein calorie malnutrition (7%), stomal ulceration (12.5%) and dumping syndrome.45 This procedure was later modified by Hess who performed a sleeve, rather than a distal gastrectomy and used DeMeester's concept of a duodenal switch (DS) to devise the BPD-DS in 1998.46

The rationale for consideration of the BPD-DS is that weight loss in super-obese patients is less successful following the LAGB and LRYGB. Indeed McLean et al. found a 43% failure rate (defined as a BMI >35kg/m2) in super-obese patients 5 years after LRYGB.47 The precise technical specifications of the BPD-DS have as yet not been standardised but typically consist of a vertical gastrectomy with resection of the greater curvature of the stomach and preservation of the antrum, pylorus and first part of the duodenum (D1). The distal 250cm of ileum is anastomosed to D1 thus permitting some duodenal contribution to the alimentary limb and the bilio-pancreatic limb is anastomosed to the distal 50–100cm of ileum. The remaining stomach volume is 150ml to reduce acid production and the incidence of marginal ulcers. The aim of this procedure was to maintain BPD- associated weight loss but to reduce the incidence of marginal ulceration, malnutrition and dumping syndrome.

Marceau et al. in 1990 modified the BPD-DS to include a longer common ileal channel of 100cm. He proposed by increasing the length of the common channel, there would be a decrease in both protein mal-absorption and diarrhoea.48 Marceau et al. also compared outcomes in 252 patients undergoing open BPD with 465 patients undergoing open BPD-DS. Mean % EWL was superior in the BPD-DS group (73%) compared to the BPD group (61%) with similar mortality rates (1.6% BPD versus 1.9% BPD-DS). The duodenal switch improved the absorption of iron and calcium and both procedures had an equivalent effect on co-morbid conditions. A laparoscopic version of this BPD-DS was performed in 1999.49 Today, the BPD-DS is usually performed laparoscopically with a 100cm common channel. As there are long-term nutritional implications with risk of anaemia and bone demineralisation, this operation is now reserved for patients with super morbid obesity (BMI >50kg/m2). Frequently, the BPD-DS will be offered to high-risk patients with very high BMI, as it may be performed in 2 stages at separate intervals. An isolated sleeve gastrectomy is initially performed and following a period of weight loss of 6–12 months, the duodenal switch may then be performed. The main contra-indications include inflammatory bowel disease (IBD), previous bowel resection, proteinuria, severe GORD, and duodenal ulceration. Some surgeons will routinely elect to perform a cholecystectomy at the time of surgery, as there is a high incidence of gallstones post-operatively.

6.1. Surgical technique 

i)Port placement

ii)Creation of sleeve gastrectomy

iii)Creation of duodeno-ileostomy

iv)Anastomosis of bilio-pancreatic limb to distal alimentary limb

v)Closure of mesenteric defects

The patient is usually placed in the reverse Trendelenburg position with legs abducted. After appropriate port placement, all branches of the gastro-epiploic arcade are divided up to the GOJ starting at the midpoint of the greater curvature. The posterior attachments of the stomach on the anterior surface of the pancreas are divided exposing the left crus of the diaphragm. Branches of the gastro-epiploic arcade are divided distally along the serosa of the stomach, stopping at 5–6cm from the pylorus. Staplers are used to create the sleeve gastrectomy. A Bougie of 32–50 French is inserted and the sleeve gastrectomy completed with the final staple firing aimed at the angle of His with complete resection of the gastric fundus. The ileum is divided 2.5m from the ileocaecal valve and the distal small bowel anastomosed to D1 with either a circular stapler technique or alternatively a side-to-side anastomosis with a linear stapler, followed by closure of the enterotomy with a running suture. The proximal divided ileum (bilio-pancreatic limb) is then anastomosed to the distal 100cm of ileum in a side-to-side fashion and the two mesenteric defects following ante-colic duodeno-ileostomy require closure. The final reconstruction is shown in Fig. 4.

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Fig. 4 Diagram of bilio-pancreatic diversion and duodenal switch.

7. Laparoscopic sleeve gastrectomy 

Laparoscopic Sleeve Gastrectomy (LSG) has emerged as a highly effective weight loss procedure (Fig. 5).

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Fig. 5 Diagram of sleeve gastrectomy.

Previously, LSG was used as the first stage of the BPD-DS but recently LSG alone is becoming a popular definitive weight loss surgery throughout the world. However, there is a paucity of long-term follow-up data for this procedure with most recent studies giving results at 1 to 2 year follow-up.53, 54, 55

LSG works to reduce weight through a combination of restrictive and hormonal mechanisms. The residual sleeve, which is formed by the lesser curvature, has low compliance thus causing significant restriction and early satiety. In addition, by resecting the greater curvature (including the fundus), the level of the “hunger” hormone ghrelin is reduced thus causing appetite reduction. The advantages of the LSG are that it is technically easier to perform and importantly, is not associated with the complications seen post-LRYGB, namely nutritional deficiencies, stomal ulceration, dumping syndrome and small bowel obstruction. The surgical technique of the LSG can be found in the section on Bilio-pancreatic Diversion and Duodenal Switch. The LSG can be performed as a first stage in high-risk super morbidly obese patients to induce weight loss and co-morbidity amelioration prior to a second stage LRYGB or BPD-DS.

Jacobs et al., in a study of 247 patients undergoing LSG, found a % EWL at 1 year of 78% (mean BMI=44.3kg/m2, n=157 patients) and a % EWL at 2 years of 75% (mean BMI 45.1kg/m2, n=40 patients).53 In the same study, the mortality was reported as 0.4% and morbidity 12%. The incidence of gastric staple line leak rate was 1.3%. Of the 39% diabetic patients, surgery resulted in cure in 82%. Menenakos et al. have also in a prospective study of 261 patients (with a median BMI of 45.7kg/m2) reported a low mortality rate of 0.7% and morbidity rate of 8.4% following LSG. The median % EWL at 1 year was 65.7% and median BMI at 1-year follow-up was 30.5kg/m2.54

8. Conclusions 

Bariatric surgery is currently the only weight loss approach that provides sustained weight loss in morbidly obese patients. The laparoscopic approach not only affords significant reductions in cardio-respiratory and surgical complications, such as incisional hernias and wound infections, but reduces length of inpatient stay and facilitates earlier return to work. The laparoscopic gastric band, laparoscopic and open gastric bypass, sleeve gastrectomy and bilio-pancreatic diversion-duodenal switch are the main weight loss surgeries currently practiced worldwide. Each procedure has its own inherent risks and weight loss profile, but overall these show low morbidity and mortality rates. These surgeries only work to reduce weight when combined with re-education of the patient in terms of diet, need for regular exercise as well as meticulous bariatric follow-up.

Conflict of interest 

None declared.