Bariatric Surgery
Bariatric Surgery
Obesity is classically described as BMI greater than 30 kg/m. However, there is an increasing recognition that not all individuals within this category are at risk of metabolic or cardiovascular disease. This may lead to a revision of existing guidelines for bariatric surgery referral, prioritising metabolic disease rather than body weight. As data accumulates, bariatric surgery may become indicated to improve glycaemic control, reduce microvascular complication rates or induce remission in those with type 2 diabetes, irrespective of BMI.
At present, the National Institute of Clinical Excellence and the American National Institute of Health guidelines state that bariatric surgery should be offered to patients with a BMI of 35–40 kg/m who have obesity related conditions such as diabetes mellitus or obstructive sleep apnoea (OSA), or in those with a BMI of 40 kg/m or greater regardless of weight related co-morbidities. Bariatric surgery for individuals with a BMI less than 35 kg/m with obesity related co-morbidities has been recommended by the International Diabetes Federation for patients with poorly controlled type 2 diabetes despite best medical care. The expansion of indications is under investigation, but bariatric surgery in people with BMIs less than 30 kg/m is not currently recommended.
If a candidate meets the criteria for surgery, then a multi-disciplinary team assessment is made as to the suitability of the candidate. This is a complex process involving psychological, surgical, dietetic and medical review to ensure that the individual is physically and psychologically fit to proceed to surgery.
The main contraindications to surgery are psychological features that indicate that a patient would not be able to cope with the impact of the procedures. There are no evidence based exclusion criteria, and pragmatic decisions based on opinion after a multi-disciplinary team assessment is currently the best that we can offer patients. Other anaesthetic risks such as the presence of cardiovascular disease have to be assessed on a case-by-case basis. The decision to operate will take into account the benefits the candidate is likely to gain and the risks peri-operatively and post-operatively. This decision is based on the available scientific evidence and the multi-disciplinary teams' experience.
The most commonly performed procedures are Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB) and sleeve gastrectomy (SG). Biliopancreatic diversion, with or without duodenal switch (BPD and BPD-DS), is best for extremely obese individuals. All procedures can be performed laparoscopically with a low rate of complications such as wound infection and incisional hernias.
There are endoscopic techniques such as intra-gastric balloons and endoscopically placed synthetic duodenojejunal bypass liners such as the EndoBarrier, which have been developed as an alternative to bariatric surgery. They are associated with a mean weight loss of 10–20%, and a complication rate of up to 20%. Complications include sleeve migration and bowel obstruction. Given the lack of long-term data at present, the role for devices such as Endobarrier remains to be determined.
RYGB involves the division of the stomach into an upper gastric pouch, which is 15–30 ml, and a lower gastric remnant. The gastric pouch is anastomosed to the jejunum after it has been divided some 30–75 cms 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 cms distal to the gastrojejunostomy (figure 1).
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Figure 1.
Roux-en-Y gastric bypass.
AGB and SG are considered restrictive procedures, although SG has been increasingly recognised to have metabolic effects comparable with RYGB. In AGB a silastic band is applied around the stomach just below the gastro-oesophageal junction, and is tightened through a subcutaneous access port by the injection or withdrawal of a saline solution (figure 2). In SG the stomach is transected vertically creating a high-pressure gastric tube and leaving a pouch of up to 200 ml (figure 3).
(Enlarge Image)
Figure 2.
Adjustable gastric banding.
(Enlarge Image)
Figure 3.
Sleeve Gastrectomy.
BPD includes a partial gastrectomy with formation of a 400 ml gastric pouch. The small bowel is divided 250 cms proximal to the ileocaecal 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 50 cms proximal to the ileocaecal valve. In BPD-DS, a vertical SG is constructed and the division of the duodenum is performed immediately beyond the pylorus. The alimentary limb is connected to the duodenum, whereas the biliopancreatic limb is anastomosed to the ileum 75–100 cms proximal to the ileocaecal valve (figure 4).
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Figure 4.
Biliopancreatic Diversion.
For each patient, the benefits of the procedure should outweigh the operative risk. Several risk factors for morbidity and mortality post-operatively have been identified in multi-centre reviews; these include male gender, age older than 50 years, congestive heart failure, peripheral vascular disease and renal impairment. While these factors may increase risk, they do not necessarily preclude an individual from bariatric surgery and need to be considered in the individual clinical context.
Obese individuals have an increased prevalence of cardiopulmonary disease, which may be undiagnosed pre-operatively. An individualised pre-operative assessment should be completed with an emphasis on screening for cardiac arrhythmia and cardiomyopathy. OSA is diagnosed in almost 70% of individuals awaiting bariatric surgery, with over 40% meeting the criteria for severe disease. However, this is not associated with a greater rate of peri-operative complications.
Predicting individual outcomes following bariatric surgery is difficult. Several predictive models have been trialled including the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) and the artificial neural network. These models incorporate psychological and biological measurements but may incorrectly predict response in as many as 30% of bariatric surgery recipients.
Investigation of genetic factors that may predict individual responses to bariatric surgery is on-going and controversial. At present, there is no recommendation to include genotyping or biomarkers in patient assessment or in the selection of bariatric procedure. However, as data accumulate, we may find serum markers or genotypes that are of clinical use in predicting individual response to bariatric surgery.
Bariatric surgery produces many benefits for the recipient, including;
Airway. Bariatric surgery can improve the severity of OSA or result in full remission. The improvement can still leave the individual in a moderate or severe category. The symptoms of asthma also improve after bariatric surgery. The mechanism of this effect is unknown, though reduction of subcutaneous tissue with improvement of the restrictive effect on the chest wall may be involved.
Body Weight. Bariatric surgery effectively induces weight loss in most surgical recipients. RYGB often results in greater weight loss than AGB, but good quality post-operative care can improve weight loss after AGB, with results comparable with RYGB. Weight loss is comparable between RYGB and SG at 36 months post-operatively. BPD results in greater weight loss but higher complication rates than RYGB.
Weight loss usually reaches a maximum 12–18 months post-operatively, and some weight regain is common thereafter. The mean 20 years weight reduction in the large Swedish Obese Subjects' study was 25% for RYGB and 15% for AGB. The aetiology of this weight regain remains poorly understood, but psychological factors including food urges and low levels of wellbeing have been implicated but not yet substantiated.
Cardiac. Obesity is a risk factor for cardiovascular disease, and bariatric surgery is associated with reduced cardiovascular mortality and morbidity. RYGB reduces cardiovascular morbidity by approximately 50% when compared with BMI and age matched controls, or those with non-surgical weight loss. The mechanism is unclear but improvements in hyperinsulinism, dyslipidaemia and hypertension probably contribute. The reduction in hypertension and dyslipidaemia does remit somewhat post-operatively but both blood pressure and serum cholesterol remain reduced from baseline at 10 years.
Cardiomyopathy in obesity is associated with left ventricular hypertrophy and diastolic dysfunction with a longer exposure to obesity associated with worse cardiac function and larger ventricular mass. Left atrial dilatation and systolic dysfunction can also develop. This is likely due to a combination of increased cardiac output and increased circulatory volume. Bariatric surgery has been shown to result in improved cardiac function and 'reverse remodelling' of the left ventricle up to 3 years post-operatively.
Type 2 Diabetes. Bariatric surgery can induce remission of obesity associated diabetes mellitus. There are enteroendocrine effects following RYGB, BPD and SG that have been associated with the greater remission rates for diabetes in these modalities when compared with patients who have had similar weight loss after AGB. Diabetes remission is greatest for patients undergoing BPD-DS, followed by RYGB and then AGB. SG only has a slightly lower remission rate compared with RYGB. The remission of diabetes may be transient, with 72% having impaired fasting glycaemia or normoglycaemia 2 years after bariatric surgery but only 36% remaining free of diabetes at 10 years.
However, these data are based on a prospective study in which the majority of participants underwent vertical banded gastroplasty. None underwent BPD or SG. The effect on diabetes remission may be greater in these groups over this timeframe. In the previous study, the RYGB group (N=34) had lower serum glucose measurements at 10 years when compared with the remainder of the cohort (N=6080). Retrospective data from 9 years following RYGB report a reduction of up to 65% in the medical treatment of diabetes.
Diabetes remission is more likely in those with a lower glycosylated haemoglobin (HbA1c) levels and pre-operative insulin independence. In those who do not achieve remission, bariatric surgery, including AGB, results in better glycaemic control and a reduced medication burden compared with intensive medical therapy. Bariatric surgery may also facilitate remission of microvascular complications. The only predictor of cardiovascular benefit after bariatric surgery appears to be raised fasting insulin levels, suggesting that patients with diabetes or insulin resistance may be the group who have most to gain in terms of cardiovascular risk reduction.
Economic. Medical costs are higher for obese individuals, mainly due to the cost of diabetic, hypertensive and lipid therapy, but with additional costs secondary to analgesia, respiratory and psychiatric treatments. There are broader socio-economic effects. Obesity is associated with reduced productivity and increased rates of sick leave. Bariatric surgery can result in increased productivity and reduced sick leave. It also reduces healthcare utility, and a return of investment can be achieved within 4 years.
Functional. Activities of daily living can be impaired by severe obesity, and this loss of autonomy is distressing for the affected individuals. Joint pain is common in obese populations and can impinge on individual functional status. Bariatric surgery results in improved function status and reduced levels of back pain. Asking a patient whether they can tie their shoes may be the diagnostic test that yields the most information. Moreover, in our clinical experience, asking a patient to climb three flights of stairs every time they attend the clinic, and noting how far they get before taking a break, can be much more informative than weighing them.
Gonadal. Obesity can be associated with sub-fertility with reduced serum testosterone levels, when corrected for sex hormone binding globulin, and reduced sperm quality found in obese men. In women, obesity is associated with high rates of ovulatory dysfunction, increased risk of spontaneous abortion and increased materno-fetal risk in pregnancy.
The data on male fertility following bariatric surgery are conflicting. Weight loss after bariatric surgery may increase serum testosterone levels but paradoxically can be associated with reduced sperm quality. Bariatric surgery can improve ovulatory cycles and reduce hyperandrogenism in women. It also probably reduces materno-fetal risk, although the current evidence is mainly limited to observational data. To date, there are no randomised controlled data or long-term prospective data available, and therefore no strong recommendation can be made on advising reproductively active men and women considering bariatric surgery.
Health Status. People who are classified as obese often report poor health perceptions and altered mood. Anxiety, depression and eating disorders are also common. Bariatric surgery improves quality of life and perceived health status, with changes seen in the 1st year and benefit retained up to 10 years. It is also associated with less depression and aggression, improved self-concept and remission of eating disorders.
While the improvements in perceived health status and quality of life may be correlated to weight loss, other factors may also contribute as the benefits have been reported in the immediate post-surgical phase. Weight regain is associated with deterioration in health status and depressive symptoms.
Image. Body image dysphoria is often found in obese cohorts. Bariatric surgery improves self-concept. The improvement in body image satisfaction is associated with improved quality of life scores, but weight regain can result in deterioration in self-concept.
Junction: Gastro-oesophagus. Gastro-oesophageal reflux disease (GORD) is found in higher frequencies in obese populations and RYGB is more effective than fundoplication to reduce GORD symptoms. Therefore, the presence of GORD supports use of RYGB as a first line procedure. SG and AGB have been associated with worsening GORD and patients with pre-existing disease may not be suitable candidates.
Kidney. There is debate on the effect of obesity on renal function. The measurement of glomerular filtration rate in obese cohorts is not well validated, but obesity has been associated with chronic kidney disease. Renal parameters such as serum creatinine and urinary protein excretion may improve after bariatric surgery, but it remains unclear if this translates to improved renal function as significant amounts of lean mass are also lost, making the interpretation of serum creatinine difficult.
Liver. Liver disease such as non-alcoholic steatohepatitis and hepatic fibrosis are associated with obesity, and can progress to cirrhosis.
Bariatric surgery improves the histological appearance of the liver, and can lead to regression of established liver disease. However, these data are often uncontrolled and some data have reported worsening in fibrosis after bariatric surgery.
Medication. Bariatric surgery results in a significant reduction in medical burden and cost, and this can take effect within 2 weeks of surgery. However, the burden and cost reduction may be partially offset in those requiring increased GORD treatment and nutritional supplementation.
Other Clinical Outcomes. There is emerging evidence that bariatric surgery may reduce the incidence of cancer, with a stronger protective effect reported in women only. In some circumstances, this effect can be understood. For example, the presence of obesity and GORD has been associated with pre-malignant metaplasia of the gastro-oesophageal junction, and frank adenocarcinoma of the oesophagus. RYGB can improve GORD and is associated with regression of pre-malignant metaplasia. The mechanisms underlying the reduced risk in other cancers are unclear, but may involve mediation of inflammatory pathways and attenuation of obesity associated hyperinsulinism.
Adjustable Gastric Banding. AGB is a safe procedure with a total mortality rate of less than 0.3%. There is a wide range in the reported complication rates, and the Longitudinal Assessment of Bariatric Surgery consortium is taken as a benchmark in bariatric centres of excellence. Vomiting is common after AGB, but bowel obstruction secondary to band migration should be considered. This is uncommon with rates as low as 1.4%.
There is no anastomosis in AGB but gastro-oesophageal perforation is an early complication that can result in abdominal sepsis with an incidence of less than 0.5%. Infections of the adjustment port can present years post-operatively, with abdominal pain or port site erythema. If caused by band erosion, then intra-abdominal sepsis can ensue and the patient requires urgent admission and intra-venous antibiotics.
Given the lack of any intestinal bypass, AGB is not likely to be associated with significant nutritional complications, although this should always be considered. The risk of nutritional deficiencies depends on post-operative weight loss and patient compliance with follow up. Post-operative hair loss has been reported in up to 4.5% following AGB, but is usually mild and non-progressive.
Roux-en-Y Gastric Bypass. RYGB is one of the most studied of the contemporary bariatric procedure, and hence has a greater volume of data on complications than other procedures. The total mortality rate for RYGB performed in centres of excellence is 0.4%. Pulmonary or venous thromboembolism are early complications and occur in less than 0.5% of recipients. Haemorrhage can occur early, with a rate of up to 4%. Anastomotic leak and bowel perforation are feared early complications in RYGB, and higher BMI, male gender, older age, re-operation and surgeon experience are all associated with higher rates of anastomotic leakage. Leakage can occur at any of the anastomotic junctions and can result in severe peritonitis, sepsis and multi-organ failure.
Vomiting is frequent after RYGB, but should be considered to be pathological until proven otherwise. Vomiting can be the result of overeating or rapid eating, and the individuals eating habit should be assessed. Cholelithiasis can occur frequently following bariatric surgery, with up to 2% of recipients affected in the first 12 months after surgery. Ultrasound of the bladder is the diagnostic tool of choice. Ursodeoxycholic acid is recommended for prevention, and should be continued for at least 6 months in those who have not undergone cholecystectomy.
Late complications that present with vomiting or bowel obstruction include internal hernias and anastomotic stricture. Internal hernias may become more common with the increased use of laparoscopic techniques. However, the use of new surgical techniques that avoid division of the mesentery may reduce the rate to as low as 1%. Often, a diagnostic laparoscopy is the investigation of choice with a much better sensitivity and specificity compared with abdominal CT.
Anastomotic stricture is a late complication that can occur at any of the anastomotic sites. It is most commonly described at the gastrojejunostomy in RYGB and is associated with dysphagia and vomiting. The mean incidence of gastrojejunal stricture is approximately 10%, but rates of as high as 20% are reported.
Marginal ulcers are another late complications of bariatric surgery. These occur in 2% of patients within the first post-operative year, and then in 0.5% for up to 5 years. Diagnosis is via gastroscopy and proton pump inhibition is the preferred treatment, but ulcers can be refractory and will then require surgical treatment.
Diarrhoea can also occur following bariatric surgery with an incidence of up to 40%. Rarely, this can deteriorate to the point of faecal incontinence. The aetiology of this is unclear and treatment is based on appropriate dietary modification and anti-diarrhoeal pharmacotherapy. A full assessment including appropriate endoscopic studies should be considered if the symptoms persist despite therapy, or if faecal incontinence develops.
There is a variable incidence of the dumping syndrome after RYGB. The clinical presentation of dumping syndrome includes abdominal pain, diarrhoea, nausea, facial flushing, palpitations, hypotension and syncope. These symptoms are so-called 'early symptoms' and usually occur within 1 h of eating. The 'late symptoms' can occur up to 3 h after the meal and include perspiration, palpitations, hunger, tremor, agitation and syncope. The treatment of dumping syndrome is dietary modification, with small regular low glycaemic index meals. Pharmacotherapy with acarbose or somatostatin analogues may be needed, with transient enteral feeding required in severe cases.
Eating disorders are often diagnosed in bariatric surgical recipients, either before or after surgery. Eating disorders, depression and anxiety disorders may negatively affect weight outcomes, although the evidence base is inconsistent to date. Additive behaviours can emerge following surgery, with substance abuse developing in some individuals.
While there are no formal recommendations on post-operative surgical psychological care, it is likely to be vital to the on-going care of the bariatric patient, as well as optimising weight loss. Screening for psychological or behavioural disturbance is encouraged, and appropriate therapy should be offered when these conditions are found.
Deficiencies in iron, vitamin B12, folate and fat-soluble vitamins occur commonly after RYGB. Nutritional supplementation needs to be individually prescribed, and regularly reviewed depending on weight loss and the presence of gastrointestinal symptoms. Serum monitoring is indicated, and the bariatric multi-disciplinary team can decide the schedule of serum monitoring. Guidelines are available, but must be individualised to be effective.
Hyperinsulinemic hypoglycaemia is an increasingly recognised complication of RYGB. Symptoms are aggravated by glucose consumption, and include palpitations, tremor, sweating and hunger, similar to the dumping syndrome. Nesidioblastosis can be considered, although the data supporting this are controversial. A GLP-1 effect may be causal in this syndrome. However, the precise aetiology is unclear to date and the current treatment is regular low glycaemic index meals. Octreotide and acarbose can also be used if needed.
Sleeve Gastrectomy. Following its introduction as a stand-alone bariatric procedure in 2004, SG has been found to be safe and effective. Given its relatively recent introduction into widespread bariatric practice, the volume of data is not as extensive as RYGB. The complications of SG include haemorrhage, anastomotic leaks and stenosis, and are found at rates that are comparable with RYGB. However, SG has been found to result in less operating time and shorter hospital stays when compared with RYGB.
While data is still being accumulated on SG, nutritional complications should still be expected, with a particular emphasis on vitamin B12 and iron. Dumping syndrome can occur following SG, but the prevalence of these and other gastrointestinal disorders remains to be established. Eating disorders should be screened for before and after SG, as in RYGB, until specific data is available.
Biliopancreatic Diversion, With or Without Duodenal Switch. As with RYGB and SG, haemorrhage, anastomotic leak and stenosis can all occur in BPD or BPD-DS. Historically, BPD has been considered a high-risk procedure, with higher rates of complications than the other major modalities. Early complications can occur more frequently, but this is in the context of higher BMI and a greater number of co-morbidities when compared with RYGB.
Long-term data records an excess weight loss of more than 65% with an incisional hernia rate of 38% in BPD/BPD-DS. There is a higher rate of discontinuation of glycaemic therapy in those with diabetes, with up to 90% of individuals discontinuing oral therapy.
Long-term follow-up of patients in bariatric surgery practice is poor, even in the best centres. We find that patients who regain weight, or who have complications, often stop attending for follow-up as they feel that they have done something wrong. Healthcare professionals could contribute to the low long-term follow-up rates as there is little to offer patients who regain weight, and patients are too easily blamed.
All bariatric recipients should however attend for regular follow-up, especially as surgery does not 'cure' obesity or the associated co-morbidities, but rather controls obesity associated disease. Follow-up can thus be used to screen for the benefits and complications of bariatric surgery mentioned above. The exact schedule will depend on the procedure and the perceived risk of complications. This will be determined by the bariatric multidisciplinary team. The following points are discussed in more detail in the previous passages, but a short synopsis of the key areas of follow-up review would include:
Airway. As the symptoms of OSA can remit, sleep apnoea therapy should be reviewed following bariatric surgery. Weight regain can lead to a relapse of OSA, requiring resumption on continuous positive airway pressure (CPAP) therapy.
Body Weight. Weight loss is expected to peak between 12 and 18 months post-operatively. Following this period, some weight gain is expected and the individuals should be supported through this phase, as it can result in psychological deterioration that can exacerbate weight regain. If the weight regain exceeds what is physiologically expected then additional interventions such as pharmacotherapy or further surgery should be considered.
Cardiovascular Disease. Blood pressure and lipid profiles should be reviewed regularly post-operatively, as both will improve while the patient remains in a negative energy balance, but can approach pre-operative levels once weight stabilises. Some patients may have continued benefit, but anti-hypertensive and lipid therapy should not be discontinued routinely. Cardiomyopathy may also remit, and in those with pre-existing cardiomyopathy, repeated echocardiograms annually may demonstrate improvement up to 3 years post-operatively.
Diabetes. The remission of diabetes has recently been defined following bariatric surgery. HbA1c levels should be measured between 3 and 6 months post-operatively, and glycaemic therapy adjusted as appropriate. Patients should remain in screening programmes to evaluate retinopathy, neuropathy and nephropathy for at least 5 years following surgery, as they can develop microvascular disease despite early remission of diabetes. If patients had pre-existing microvascular complications, or they have a fasting blood glucose above 5.6 mmol/l or a HbA1c greater than 42 mmol/mol (6% DCCT), then they should continue with screening programmes as all patients with type 2 diabetes would.
Yearly fasting glucose and HbA1c measurements remain the best methods of monitoring long-term glycaemic control, as oral glucose tolerance tests can provoke dumping syndromes, and could therefore generate false results. This is especially true of RYGB, where exaggerated postprandial secretion of insulin can cause hypoglycaemia when patients are challenged with glycaemic stimuli.
Weight regain is often associated with relapse of diabetes and screening frequency may therefore need to be adapted in patients with more than 2 kg in weight gain per year.
Economic. Medical use and costs are likely to decrease following surgery, and prescribed therapy should be reviewed at each post-operative visit. Many people increase their productivity and reduce healthcare expenditure in the months after bariatric surgery. Therefore, individuals who have recovered from the surgery can expect to return to work within 2–8 weeks, depending on the local bariatric teams' practice and the individual post-operative recovery.
Functional. The individuals' functional status is expected to improve post-operatively. In rare and extreme cases of dysfunction, physiotherapists and occupation therapists may need to re-evaluate patients 12 months following surgery. The individuals' needs may change with respect to mobility devices and other aids, and the rate of any change will be specific to the individual. Therefore, the bariatric multidisciplinary team should schedule a functional review at an appropriate stage post-operatively.
Gonadal. Gonadal function and fertility may improve very quickly after bariatric surgery. In couples who do not wish to become pregnant, they should be advised on appropriate barrier contraception until weight loss stabilises, and formal gonadal reassessment is appropriate.
Menstrual history should be reviewed at each clinic visit as appropriate. In couples considering pregnancy, a period of 9–18 months after surgery is usually recommended before considering reproductive assessment, but if they remain sub-fertile after peak weight loss, referral to a reproductive medical clinic is indicated.
Health Status. The immediate post-operative phase is associated with improved psychological health, but depression and eating disorders can emerge, especially in those with weight regain. In those struggling with their new eating pattern, dietetic and psychological input is needed. If a serious problem is suspected, then specialist psychological input is urgently required. Increased incidence of alcohol abuse is controversial, but patients should be questioned about their alcohol intake as routine after surgery. Pre-operative expectations of what surgery can achieve are often not met and patients should be counselled that mood and anxiety usually remains unchanged, but that depression secondary to obesity related problems improves.
Image. Body image and self-concept should be assessed regularly, and can be expected to return to the baseline. There is not a linear relationship between improvement and weight loss. Depression and low self-esteem can deteriorate, and psychological support should be available to those who need it, and especially those with weight regain.
Junction: Gastro-oesophagus. GORD symptomatology improve after RYGB. However, it can occur de novo or become worse after AGB and SG. Therefore, follow-up should include a screen for GORD symptoms and initiation of appropriate therapy as needed.
Kidney. Serum creatinine should be monitored in those with pre-existing renal impairment. After discharge, a repeated sample at 4 weeks post-operatively and then 6-monthly is prudent but not strongly evidence based. Serum creatinine will reduce secondary to weight loss, and this should not be mistaken as improved renal function. Post-operative urinary collections for proteinuria should be completed in those with pre-operative proteinuria. An interval of no sooner than 4 weeks and no later than 6 months should be planned for the first post-operative collection.
Theoretical concerns have centred on the rapid improvement in glycaemic control in patients with type 2 diabetes mellitus, and the possible deleterious effects that this could have on microvascular disease. Current prospective studies in relevant cohorts have not identified any consistent problems with regards to kidney disease.
Liver. The prognosis for obesity associated liver disease remains unclear. Therefore, liver function tests are an important part of post-operative care, especially in those with pre-surgical diseases. A standard liver enzyme panel is acceptable, with measurement of prothrombin time and albumin in those with cirrhotic disease. The interval at which this should be processed depends on the individual circumstance, but a routine panel at 3 months and then 6 monthly until weight loss stabilises is reasonable, although not evidence based.
Medication. Bariatric surgery results in a significant reduction in medical burden and cost in most recipients, and the indication for all prescribed medical therapy should be kept under regular review. Many pre-operatively prescribed anti-hypertensive, lipid and glycaemic therapies could have dose reductions in the 12 months after surgery. Medication that may cause hypoglycaemia should be carefully titrated.
Nutritional Screening. Given the propensity for micronutrient deficiencies in the obese with altered absorption after surgery, regular serum monitoring of calcium, albumin, vitamin B12, folate and iron studies with a full blood count is essential. In those with hypocalcaemia, or those otherwise at risk of vitamin D deficiency, this should also be monitored. The individual schedule should be determined by the multidisciplinary team, but a full nutritional panel should be completed within the first 3 months post-operatively. The value of regular trace elements and vitamin supplementation has not yet been established.
Review
Obesity: The Diagnosis and Candidate Selection
Obesity is classically described as BMI greater than 30 kg/m. However, there is an increasing recognition that not all individuals within this category are at risk of metabolic or cardiovascular disease. This may lead to a revision of existing guidelines for bariatric surgery referral, prioritising metabolic disease rather than body weight. As data accumulates, bariatric surgery may become indicated to improve glycaemic control, reduce microvascular complication rates or induce remission in those with type 2 diabetes, irrespective of BMI.
At present, the National Institute of Clinical Excellence and the American National Institute of Health guidelines state that bariatric surgery should be offered to patients with a BMI of 35–40 kg/m who have obesity related conditions such as diabetes mellitus or obstructive sleep apnoea (OSA), or in those with a BMI of 40 kg/m or greater regardless of weight related co-morbidities. Bariatric surgery for individuals with a BMI less than 35 kg/m with obesity related co-morbidities has been recommended by the International Diabetes Federation for patients with poorly controlled type 2 diabetes despite best medical care. The expansion of indications is under investigation, but bariatric surgery in people with BMIs less than 30 kg/m is not currently recommended.
If a candidate meets the criteria for surgery, then a multi-disciplinary team assessment is made as to the suitability of the candidate. This is a complex process involving psychological, surgical, dietetic and medical review to ensure that the individual is physically and psychologically fit to proceed to surgery.
The main contraindications to surgery are psychological features that indicate that a patient would not be able to cope with the impact of the procedures. There are no evidence based exclusion criteria, and pragmatic decisions based on opinion after a multi-disciplinary team assessment is currently the best that we can offer patients. Other anaesthetic risks such as the presence of cardiovascular disease have to be assessed on a case-by-case basis. The decision to operate will take into account the benefits the candidate is likely to gain and the risks peri-operatively and post-operatively. This decision is based on the available scientific evidence and the multi-disciplinary teams' experience.
Techniques: Available Options in Bariatric Surgery
The most commonly performed procedures are Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB) and sleeve gastrectomy (SG). Biliopancreatic diversion, with or without duodenal switch (BPD and BPD-DS), is best for extremely obese individuals. All procedures can be performed laparoscopically with a low rate of complications such as wound infection and incisional hernias.
There are endoscopic techniques such as intra-gastric balloons and endoscopically placed synthetic duodenojejunal bypass liners such as the EndoBarrier, which have been developed as an alternative to bariatric surgery. They are associated with a mean weight loss of 10–20%, and a complication rate of up to 20%. Complications include sleeve migration and bowel obstruction. Given the lack of long-term data at present, the role for devices such as Endobarrier remains to be determined.
RYGB involves the division of the stomach into an upper gastric pouch, which is 15–30 ml, and a lower gastric remnant. The gastric pouch is anastomosed to the jejunum after it has been divided some 30–75 cms 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 cms distal to the gastrojejunostomy (figure 1).
(Enlarge Image)
Figure 1.
Roux-en-Y gastric bypass.
AGB and SG are considered restrictive procedures, although SG has been increasingly recognised to have metabolic effects comparable with RYGB. In AGB a silastic band is applied around the stomach just below the gastro-oesophageal junction, and is tightened through a subcutaneous access port by the injection or withdrawal of a saline solution (figure 2). In SG the stomach is transected vertically creating a high-pressure gastric tube and leaving a pouch of up to 200 ml (figure 3).
(Enlarge Image)
Figure 2.
Adjustable gastric banding.
(Enlarge Image)
Figure 3.
Sleeve Gastrectomy.
BPD includes a partial gastrectomy with formation of a 400 ml gastric pouch. The small bowel is divided 250 cms proximal to the ileocaecal 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 50 cms proximal to the ileocaecal valve. In BPD-DS, a vertical SG is constructed and the division of the duodenum is performed immediately beyond the pylorus. The alimentary limb is connected to the duodenum, whereas the biliopancreatic limb is anastomosed to the ileum 75–100 cms proximal to the ileocaecal valve (figure 4).
(Enlarge Image)
Figure 4.
Biliopancreatic Diversion.
Risk: Pre-operative Assessment and Predicting Outcomes
For each patient, the benefits of the procedure should outweigh the operative risk. Several risk factors for morbidity and mortality post-operatively have been identified in multi-centre reviews; these include male gender, age older than 50 years, congestive heart failure, peripheral vascular disease and renal impairment. While these factors may increase risk, they do not necessarily preclude an individual from bariatric surgery and need to be considered in the individual clinical context.
Obese individuals have an increased prevalence of cardiopulmonary disease, which may be undiagnosed pre-operatively. An individualised pre-operative assessment should be completed with an emphasis on screening for cardiac arrhythmia and cardiomyopathy. OSA is diagnosed in almost 70% of individuals awaiting bariatric surgery, with over 40% meeting the criteria for severe disease. However, this is not associated with a greater rate of peri-operative complications.
Predicting individual outcomes following bariatric surgery is difficult. Several predictive models have been trialled including the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) and the artificial neural network. These models incorporate psychological and biological measurements but may incorrectly predict response in as many as 30% of bariatric surgery recipients.
Investigation of genetic factors that may predict individual responses to bariatric surgery is on-going and controversial. At present, there is no recommendation to include genotyping or biomarkers in patient assessment or in the selection of bariatric procedure. However, as data accumulate, we may find serum markers or genotypes that are of clinical use in predicting individual response to bariatric surgery.
Benefits: Clinical Outcomes Following Bariatric Surgery
Bariatric surgery produces many benefits for the recipient, including;
Airway. Bariatric surgery can improve the severity of OSA or result in full remission. The improvement can still leave the individual in a moderate or severe category. The symptoms of asthma also improve after bariatric surgery. The mechanism of this effect is unknown, though reduction of subcutaneous tissue with improvement of the restrictive effect on the chest wall may be involved.
Body Weight. Bariatric surgery effectively induces weight loss in most surgical recipients. RYGB often results in greater weight loss than AGB, but good quality post-operative care can improve weight loss after AGB, with results comparable with RYGB. Weight loss is comparable between RYGB and SG at 36 months post-operatively. BPD results in greater weight loss but higher complication rates than RYGB.
Weight loss usually reaches a maximum 12–18 months post-operatively, and some weight regain is common thereafter. The mean 20 years weight reduction in the large Swedish Obese Subjects' study was 25% for RYGB and 15% for AGB. The aetiology of this weight regain remains poorly understood, but psychological factors including food urges and low levels of wellbeing have been implicated but not yet substantiated.
Cardiac. Obesity is a risk factor for cardiovascular disease, and bariatric surgery is associated with reduced cardiovascular mortality and morbidity. RYGB reduces cardiovascular morbidity by approximately 50% when compared with BMI and age matched controls, or those with non-surgical weight loss. The mechanism is unclear but improvements in hyperinsulinism, dyslipidaemia and hypertension probably contribute. The reduction in hypertension and dyslipidaemia does remit somewhat post-operatively but both blood pressure and serum cholesterol remain reduced from baseline at 10 years.
Cardiomyopathy in obesity is associated with left ventricular hypertrophy and diastolic dysfunction with a longer exposure to obesity associated with worse cardiac function and larger ventricular mass. Left atrial dilatation and systolic dysfunction can also develop. This is likely due to a combination of increased cardiac output and increased circulatory volume. Bariatric surgery has been shown to result in improved cardiac function and 'reverse remodelling' of the left ventricle up to 3 years post-operatively.
Type 2 Diabetes. Bariatric surgery can induce remission of obesity associated diabetes mellitus. There are enteroendocrine effects following RYGB, BPD and SG that have been associated with the greater remission rates for diabetes in these modalities when compared with patients who have had similar weight loss after AGB. Diabetes remission is greatest for patients undergoing BPD-DS, followed by RYGB and then AGB. SG only has a slightly lower remission rate compared with RYGB. The remission of diabetes may be transient, with 72% having impaired fasting glycaemia or normoglycaemia 2 years after bariatric surgery but only 36% remaining free of diabetes at 10 years.
However, these data are based on a prospective study in which the majority of participants underwent vertical banded gastroplasty. None underwent BPD or SG. The effect on diabetes remission may be greater in these groups over this timeframe. In the previous study, the RYGB group (N=34) had lower serum glucose measurements at 10 years when compared with the remainder of the cohort (N=6080). Retrospective data from 9 years following RYGB report a reduction of up to 65% in the medical treatment of diabetes.
Diabetes remission is more likely in those with a lower glycosylated haemoglobin (HbA1c) levels and pre-operative insulin independence. In those who do not achieve remission, bariatric surgery, including AGB, results in better glycaemic control and a reduced medication burden compared with intensive medical therapy. Bariatric surgery may also facilitate remission of microvascular complications. The only predictor of cardiovascular benefit after bariatric surgery appears to be raised fasting insulin levels, suggesting that patients with diabetes or insulin resistance may be the group who have most to gain in terms of cardiovascular risk reduction.
Economic. Medical costs are higher for obese individuals, mainly due to the cost of diabetic, hypertensive and lipid therapy, but with additional costs secondary to analgesia, respiratory and psychiatric treatments. There are broader socio-economic effects. Obesity is associated with reduced productivity and increased rates of sick leave. Bariatric surgery can result in increased productivity and reduced sick leave. It also reduces healthcare utility, and a return of investment can be achieved within 4 years.
Functional. Activities of daily living can be impaired by severe obesity, and this loss of autonomy is distressing for the affected individuals. Joint pain is common in obese populations and can impinge on individual functional status. Bariatric surgery results in improved function status and reduced levels of back pain. Asking a patient whether they can tie their shoes may be the diagnostic test that yields the most information. Moreover, in our clinical experience, asking a patient to climb three flights of stairs every time they attend the clinic, and noting how far they get before taking a break, can be much more informative than weighing them.
Gonadal. Obesity can be associated with sub-fertility with reduced serum testosterone levels, when corrected for sex hormone binding globulin, and reduced sperm quality found in obese men. In women, obesity is associated with high rates of ovulatory dysfunction, increased risk of spontaneous abortion and increased materno-fetal risk in pregnancy.
The data on male fertility following bariatric surgery are conflicting. Weight loss after bariatric surgery may increase serum testosterone levels but paradoxically can be associated with reduced sperm quality. Bariatric surgery can improve ovulatory cycles and reduce hyperandrogenism in women. It also probably reduces materno-fetal risk, although the current evidence is mainly limited to observational data. To date, there are no randomised controlled data or long-term prospective data available, and therefore no strong recommendation can be made on advising reproductively active men and women considering bariatric surgery.
Health Status. People who are classified as obese often report poor health perceptions and altered mood. Anxiety, depression and eating disorders are also common. Bariatric surgery improves quality of life and perceived health status, with changes seen in the 1st year and benefit retained up to 10 years. It is also associated with less depression and aggression, improved self-concept and remission of eating disorders.
While the improvements in perceived health status and quality of life may be correlated to weight loss, other factors may also contribute as the benefits have been reported in the immediate post-surgical phase. Weight regain is associated with deterioration in health status and depressive symptoms.
Image. Body image dysphoria is often found in obese cohorts. Bariatric surgery improves self-concept. The improvement in body image satisfaction is associated with improved quality of life scores, but weight regain can result in deterioration in self-concept.
Junction: Gastro-oesophagus. Gastro-oesophageal reflux disease (GORD) is found in higher frequencies in obese populations and RYGB is more effective than fundoplication to reduce GORD symptoms. Therefore, the presence of GORD supports use of RYGB as a first line procedure. SG and AGB have been associated with worsening GORD and patients with pre-existing disease may not be suitable candidates.
Kidney. There is debate on the effect of obesity on renal function. The measurement of glomerular filtration rate in obese cohorts is not well validated, but obesity has been associated with chronic kidney disease. Renal parameters such as serum creatinine and urinary protein excretion may improve after bariatric surgery, but it remains unclear if this translates to improved renal function as significant amounts of lean mass are also lost, making the interpretation of serum creatinine difficult.
Liver. Liver disease such as non-alcoholic steatohepatitis and hepatic fibrosis are associated with obesity, and can progress to cirrhosis.
Bariatric surgery improves the histological appearance of the liver, and can lead to regression of established liver disease. However, these data are often uncontrolled and some data have reported worsening in fibrosis after bariatric surgery.
Medication. Bariatric surgery results in a significant reduction in medical burden and cost, and this can take effect within 2 weeks of surgery. However, the burden and cost reduction may be partially offset in those requiring increased GORD treatment and nutritional supplementation.
Other Clinical Outcomes. There is emerging evidence that bariatric surgery may reduce the incidence of cancer, with a stronger protective effect reported in women only. In some circumstances, this effect can be understood. For example, the presence of obesity and GORD has been associated with pre-malignant metaplasia of the gastro-oesophageal junction, and frank adenocarcinoma of the oesophagus. RYGB can improve GORD and is associated with regression of pre-malignant metaplasia. The mechanisms underlying the reduced risk in other cancers are unclear, but may involve mediation of inflammatory pathways and attenuation of obesity associated hyperinsulinism.
Complications After Bariatric Surgery
Adjustable Gastric Banding. AGB is a safe procedure with a total mortality rate of less than 0.3%. There is a wide range in the reported complication rates, and the Longitudinal Assessment of Bariatric Surgery consortium is taken as a benchmark in bariatric centres of excellence. Vomiting is common after AGB, but bowel obstruction secondary to band migration should be considered. This is uncommon with rates as low as 1.4%.
There is no anastomosis in AGB but gastro-oesophageal perforation is an early complication that can result in abdominal sepsis with an incidence of less than 0.5%. Infections of the adjustment port can present years post-operatively, with abdominal pain or port site erythema. If caused by band erosion, then intra-abdominal sepsis can ensue and the patient requires urgent admission and intra-venous antibiotics.
Given the lack of any intestinal bypass, AGB is not likely to be associated with significant nutritional complications, although this should always be considered. The risk of nutritional deficiencies depends on post-operative weight loss and patient compliance with follow up. Post-operative hair loss has been reported in up to 4.5% following AGB, but is usually mild and non-progressive.
Roux-en-Y Gastric Bypass. RYGB is one of the most studied of the contemporary bariatric procedure, and hence has a greater volume of data on complications than other procedures. The total mortality rate for RYGB performed in centres of excellence is 0.4%. Pulmonary or venous thromboembolism are early complications and occur in less than 0.5% of recipients. Haemorrhage can occur early, with a rate of up to 4%. Anastomotic leak and bowel perforation are feared early complications in RYGB, and higher BMI, male gender, older age, re-operation and surgeon experience are all associated with higher rates of anastomotic leakage. Leakage can occur at any of the anastomotic junctions and can result in severe peritonitis, sepsis and multi-organ failure.
Vomiting is frequent after RYGB, but should be considered to be pathological until proven otherwise. Vomiting can be the result of overeating or rapid eating, and the individuals eating habit should be assessed. Cholelithiasis can occur frequently following bariatric surgery, with up to 2% of recipients affected in the first 12 months after surgery. Ultrasound of the bladder is the diagnostic tool of choice. Ursodeoxycholic acid is recommended for prevention, and should be continued for at least 6 months in those who have not undergone cholecystectomy.
Late complications that present with vomiting or bowel obstruction include internal hernias and anastomotic stricture. Internal hernias may become more common with the increased use of laparoscopic techniques. However, the use of new surgical techniques that avoid division of the mesentery may reduce the rate to as low as 1%. Often, a diagnostic laparoscopy is the investigation of choice with a much better sensitivity and specificity compared with abdominal CT.
Anastomotic stricture is a late complication that can occur at any of the anastomotic sites. It is most commonly described at the gastrojejunostomy in RYGB and is associated with dysphagia and vomiting. The mean incidence of gastrojejunal stricture is approximately 10%, but rates of as high as 20% are reported.
Marginal ulcers are another late complications of bariatric surgery. These occur in 2% of patients within the first post-operative year, and then in 0.5% for up to 5 years. Diagnosis is via gastroscopy and proton pump inhibition is the preferred treatment, but ulcers can be refractory and will then require surgical treatment.
Diarrhoea can also occur following bariatric surgery with an incidence of up to 40%. Rarely, this can deteriorate to the point of faecal incontinence. The aetiology of this is unclear and treatment is based on appropriate dietary modification and anti-diarrhoeal pharmacotherapy. A full assessment including appropriate endoscopic studies should be considered if the symptoms persist despite therapy, or if faecal incontinence develops.
There is a variable incidence of the dumping syndrome after RYGB. The clinical presentation of dumping syndrome includes abdominal pain, diarrhoea, nausea, facial flushing, palpitations, hypotension and syncope. These symptoms are so-called 'early symptoms' and usually occur within 1 h of eating. The 'late symptoms' can occur up to 3 h after the meal and include perspiration, palpitations, hunger, tremor, agitation and syncope. The treatment of dumping syndrome is dietary modification, with small regular low glycaemic index meals. Pharmacotherapy with acarbose or somatostatin analogues may be needed, with transient enteral feeding required in severe cases.
Eating disorders are often diagnosed in bariatric surgical recipients, either before or after surgery. Eating disorders, depression and anxiety disorders may negatively affect weight outcomes, although the evidence base is inconsistent to date. Additive behaviours can emerge following surgery, with substance abuse developing in some individuals.
While there are no formal recommendations on post-operative surgical psychological care, it is likely to be vital to the on-going care of the bariatric patient, as well as optimising weight loss. Screening for psychological or behavioural disturbance is encouraged, and appropriate therapy should be offered when these conditions are found.
Deficiencies in iron, vitamin B12, folate and fat-soluble vitamins occur commonly after RYGB. Nutritional supplementation needs to be individually prescribed, and regularly reviewed depending on weight loss and the presence of gastrointestinal symptoms. Serum monitoring is indicated, and the bariatric multi-disciplinary team can decide the schedule of serum monitoring. Guidelines are available, but must be individualised to be effective.
Hyperinsulinemic hypoglycaemia is an increasingly recognised complication of RYGB. Symptoms are aggravated by glucose consumption, and include palpitations, tremor, sweating and hunger, similar to the dumping syndrome. Nesidioblastosis can be considered, although the data supporting this are controversial. A GLP-1 effect may be causal in this syndrome. However, the precise aetiology is unclear to date and the current treatment is regular low glycaemic index meals. Octreotide and acarbose can also be used if needed.
Sleeve Gastrectomy. Following its introduction as a stand-alone bariatric procedure in 2004, SG has been found to be safe and effective. Given its relatively recent introduction into widespread bariatric practice, the volume of data is not as extensive as RYGB. The complications of SG include haemorrhage, anastomotic leaks and stenosis, and are found at rates that are comparable with RYGB. However, SG has been found to result in less operating time and shorter hospital stays when compared with RYGB.
While data is still being accumulated on SG, nutritional complications should still be expected, with a particular emphasis on vitamin B12 and iron. Dumping syndrome can occur following SG, but the prevalence of these and other gastrointestinal disorders remains to be established. Eating disorders should be screened for before and after SG, as in RYGB, until specific data is available.
Biliopancreatic Diversion, With or Without Duodenal Switch. As with RYGB and SG, haemorrhage, anastomotic leak and stenosis can all occur in BPD or BPD-DS. Historically, BPD has been considered a high-risk procedure, with higher rates of complications than the other major modalities. Early complications can occur more frequently, but this is in the context of higher BMI and a greater number of co-morbidities when compared with RYGB.
Long-term data records an excess weight loss of more than 65% with an incisional hernia rate of 38% in BPD/BPD-DS. There is a higher rate of discontinuation of glycaemic therapy in those with diabetes, with up to 90% of individuals discontinuing oral therapy.
Investigations and Follow-up
Long-term follow-up of patients in bariatric surgery practice is poor, even in the best centres. We find that patients who regain weight, or who have complications, often stop attending for follow-up as they feel that they have done something wrong. Healthcare professionals could contribute to the low long-term follow-up rates as there is little to offer patients who regain weight, and patients are too easily blamed.
All bariatric recipients should however attend for regular follow-up, especially as surgery does not 'cure' obesity or the associated co-morbidities, but rather controls obesity associated disease. Follow-up can thus be used to screen for the benefits and complications of bariatric surgery mentioned above. The exact schedule will depend on the procedure and the perceived risk of complications. This will be determined by the bariatric multidisciplinary team. The following points are discussed in more detail in the previous passages, but a short synopsis of the key areas of follow-up review would include:
Airway. As the symptoms of OSA can remit, sleep apnoea therapy should be reviewed following bariatric surgery. Weight regain can lead to a relapse of OSA, requiring resumption on continuous positive airway pressure (CPAP) therapy.
Body Weight. Weight loss is expected to peak between 12 and 18 months post-operatively. Following this period, some weight gain is expected and the individuals should be supported through this phase, as it can result in psychological deterioration that can exacerbate weight regain. If the weight regain exceeds what is physiologically expected then additional interventions such as pharmacotherapy or further surgery should be considered.
Cardiovascular Disease. Blood pressure and lipid profiles should be reviewed regularly post-operatively, as both will improve while the patient remains in a negative energy balance, but can approach pre-operative levels once weight stabilises. Some patients may have continued benefit, but anti-hypertensive and lipid therapy should not be discontinued routinely. Cardiomyopathy may also remit, and in those with pre-existing cardiomyopathy, repeated echocardiograms annually may demonstrate improvement up to 3 years post-operatively.
Diabetes. The remission of diabetes has recently been defined following bariatric surgery. HbA1c levels should be measured between 3 and 6 months post-operatively, and glycaemic therapy adjusted as appropriate. Patients should remain in screening programmes to evaluate retinopathy, neuropathy and nephropathy for at least 5 years following surgery, as they can develop microvascular disease despite early remission of diabetes. If patients had pre-existing microvascular complications, or they have a fasting blood glucose above 5.6 mmol/l or a HbA1c greater than 42 mmol/mol (6% DCCT), then they should continue with screening programmes as all patients with type 2 diabetes would.
Yearly fasting glucose and HbA1c measurements remain the best methods of monitoring long-term glycaemic control, as oral glucose tolerance tests can provoke dumping syndromes, and could therefore generate false results. This is especially true of RYGB, where exaggerated postprandial secretion of insulin can cause hypoglycaemia when patients are challenged with glycaemic stimuli.
Weight regain is often associated with relapse of diabetes and screening frequency may therefore need to be adapted in patients with more than 2 kg in weight gain per year.
Economic. Medical use and costs are likely to decrease following surgery, and prescribed therapy should be reviewed at each post-operative visit. Many people increase their productivity and reduce healthcare expenditure in the months after bariatric surgery. Therefore, individuals who have recovered from the surgery can expect to return to work within 2–8 weeks, depending on the local bariatric teams' practice and the individual post-operative recovery.
Functional. The individuals' functional status is expected to improve post-operatively. In rare and extreme cases of dysfunction, physiotherapists and occupation therapists may need to re-evaluate patients 12 months following surgery. The individuals' needs may change with respect to mobility devices and other aids, and the rate of any change will be specific to the individual. Therefore, the bariatric multidisciplinary team should schedule a functional review at an appropriate stage post-operatively.
Gonadal. Gonadal function and fertility may improve very quickly after bariatric surgery. In couples who do not wish to become pregnant, they should be advised on appropriate barrier contraception until weight loss stabilises, and formal gonadal reassessment is appropriate.
Menstrual history should be reviewed at each clinic visit as appropriate. In couples considering pregnancy, a period of 9–18 months after surgery is usually recommended before considering reproductive assessment, but if they remain sub-fertile after peak weight loss, referral to a reproductive medical clinic is indicated.
Health Status. The immediate post-operative phase is associated with improved psychological health, but depression and eating disorders can emerge, especially in those with weight regain. In those struggling with their new eating pattern, dietetic and psychological input is needed. If a serious problem is suspected, then specialist psychological input is urgently required. Increased incidence of alcohol abuse is controversial, but patients should be questioned about their alcohol intake as routine after surgery. Pre-operative expectations of what surgery can achieve are often not met and patients should be counselled that mood and anxiety usually remains unchanged, but that depression secondary to obesity related problems improves.
Image. Body image and self-concept should be assessed regularly, and can be expected to return to the baseline. There is not a linear relationship between improvement and weight loss. Depression and low self-esteem can deteriorate, and psychological support should be available to those who need it, and especially those with weight regain.
Junction: Gastro-oesophagus. GORD symptomatology improve after RYGB. However, it can occur de novo or become worse after AGB and SG. Therefore, follow-up should include a screen for GORD symptoms and initiation of appropriate therapy as needed.
Kidney. Serum creatinine should be monitored in those with pre-existing renal impairment. After discharge, a repeated sample at 4 weeks post-operatively and then 6-monthly is prudent but not strongly evidence based. Serum creatinine will reduce secondary to weight loss, and this should not be mistaken as improved renal function. Post-operative urinary collections for proteinuria should be completed in those with pre-operative proteinuria. An interval of no sooner than 4 weeks and no later than 6 months should be planned for the first post-operative collection.
Theoretical concerns have centred on the rapid improvement in glycaemic control in patients with type 2 diabetes mellitus, and the possible deleterious effects that this could have on microvascular disease. Current prospective studies in relevant cohorts have not identified any consistent problems with regards to kidney disease.
Liver. The prognosis for obesity associated liver disease remains unclear. Therefore, liver function tests are an important part of post-operative care, especially in those with pre-surgical diseases. A standard liver enzyme panel is acceptable, with measurement of prothrombin time and albumin in those with cirrhotic disease. The interval at which this should be processed depends on the individual circumstance, but a routine panel at 3 months and then 6 monthly until weight loss stabilises is reasonable, although not evidence based.
Medication. Bariatric surgery results in a significant reduction in medical burden and cost in most recipients, and the indication for all prescribed medical therapy should be kept under regular review. Many pre-operatively prescribed anti-hypertensive, lipid and glycaemic therapies could have dose reductions in the 12 months after surgery. Medication that may cause hypoglycaemia should be carefully titrated.
Nutritional Screening. Given the propensity for micronutrient deficiencies in the obese with altered absorption after surgery, regular serum monitoring of calcium, albumin, vitamin B12, folate and iron studies with a full blood count is essential. In those with hypocalcaemia, or those otherwise at risk of vitamin D deficiency, this should also be monitored. The individual schedule should be determined by the multidisciplinary team, but a full nutritional panel should be completed within the first 3 months post-operatively. The value of regular trace elements and vitamin supplementation has not yet been established.
