The sleeve gastrectomy has been gaining in popularity over the last decade. Laparoscopically, the surgeon uses a stapling device to staple along the length of the stomach, removing the majority of the fundus, leaving a thin tube of lesser curve (Fig. 15.2). Through this, food passes down and out of the stomach, but the volume is significantly restricted.

Although the sleeve gastrectomy is thought to alter metabolism slightly in that hormones produced in the stomach which affect eating (i.e. ghrelin) are reduced, the sleeve is primarily a restrictive operation. Patients require multivitamins lifelong to offset any nutritional abnormalities caused following the sleeve, and this is especially important in the context of post-operative fertility and pregnancy.

Weight loss is usually around 60–75 % of excess body weight [11] and this amount of weight can significantly alter comorbidities. Diabetes resolution for example has been shown in 50–90 % of patients at 3 years [12].

The sleeve gastrectomy is an irreversible procedure. In cases where significant weight loss has not been achieved, it can be converted to a roux-en-y gastric bypass with relative ease. The mortality for sleeve gastrectomy approaches zero [13], and long-term complications are significantly fewer than with gastric banding. In the short term following surgery, complications include staple line bleed or leak, port site haematoma and operative risks such as pulmonary embolism, myocardial infarction and wound infection. Long-term, the main complications include a stricture at the staple line, which may need endoscopic dilatation, or laparoscopic port site hernia.

As the sleeve is primarily a restrictive operation, it can also be cheated by the patient eating high calorie foods such as cream and chocolate, therefore, like with all operations, the patient needs to be committed to changing their eating habits and lifestyles before embarking upon surgery.

The gastric bypass is often considered the “gold standard” of bariatric operations. It contains both a restrictive and malabsorptive component, thereby assisting the patient to lose on average 60–80 % of their excess weight. A small pouch of stomach, around the size of an eggcup, is created by stapling off and separating the majority of the stomach. A loop of small bowel is disconnected downstream (distance dependent on surgeons practice) and the distal end brought up to anastomose with the stomach pouch (Fig. 15.3).

The proximal end of bowel, which is still connected to the duodenum and stomach, is then re-anastomosed at a variable distance downstream from the gastro-jejunal anastomosis. When consumed, foodstuffs pass through the pouch, and down the jejunum, where it is joined by the digestive juices from the stomach, pancreas and biliary tree at the distal jejunal-jejunal anastomosis. Form here on digestion is normal.

The bypass works by both restricting the volume of food that can be consumed in any one sitting as food has to pass out of the pouch before more can be eaten, and by limiting the absorption of food by bypassing on average around 2 m of small bowel. Although technically possible, reversal of the bypass is extremely difficult and will never fully restore normal anatomy. Therefore reversal will only be considered in the cases of extreme weight loss, although this is rare. Operative complication includes myocardial infarction, pulmonary embolism, anastomotic bleed or leak and port site haematoma. Longer-term complications include anastomotic strictures requiring endoscopic dilatation and hernias, both internal (due to the mesenteric defects created) and port site. Rarely, fistulae between the remnant stomach and bowel have been seen, which generally lead to weight regain.

Following the bypass, nutritional deficiencies are common and therefore patients require daily multivitamins, along with yearly blood tests with their general practitioner. This is particularly important for women attempting to conceive and carry a healthy child, therefore it is often advised that patients take pre-natal vitamins whilst attempting to conceive. There is some concern that in pregnant women, the growing fetus can stretch the bowel and damage the anastomosis, although this is not based in evidence and many successful pregnancies occur after roux-en-y gastric bypass.

The biliopancreatic diversion and duodenal switch operations work in a similar manner to the gastric bypass, although in many cases the majority of the stomach is physically removed. The amount of small bowel bypassed is longer, leading to an increased degree of malabsorption and malnutrition. Although excess weight loss can be as high as 90 %, this procedure is rarely performed in the UK due to its severe malnutrition side effects. Today, this operation is mainly reserved for those who have failed to lose weight following the roux-en-y gastric bypass. Given that it is more likely to cause nutritional abnormalities and malnourishment, it should perhaps not be considered for women who wish to have a family after surgery.

Not strictly an operation, the intra-gastric balloon is placed endoscopically into the stomach and inflated. It is left in situ for 6 months, after which it is removed endoscopically. This procedure does not require a general anaesthetic, therefore may seem attractive as a temporary weight loss solution. The balloon also works by restricting the amount of food that can be eaten as the balloon fills approximately half the stomach, inducing early satiety.

Weight loss following insertion of the intra-gastric balloon is usually limited, as the stomach can still stretch around it, admitting foodstuffs. The balloon is often used as a stop-gap measure in patients who are awaiting a bariatric operation, but whom desperately need to lose weight in order for them to safely undergo a general anaesthetic.

Weight regain is a common problem following bariatric surgery. Numerous studies have demonstrated significant levels of weight regain, in some cases more than 15 % of the excess weight lost. Bariatric clinics are increasingly receiving referrals from patients whom have previously undergone surgery but whom have regained their excess weight and who wish to be considered for further surgery. Although this is in part to the limited dietary and psychological follow up that patients receive it is also due to the unrealistic expectations of many patients [14, 15] who fail to adapt their eating habits following surgery, believing instead that surgery is a magic cure.

Although the concept of weight regain in the absence of obesity related comorbidities is less troublesome, where comorbidities exist before surgery, any weight regain could lead to a resurgence of these medical problems. Many patients find their type 2 diabetes or hypertension to recur, which will cause problems during pregnancy and can lead to hyperglycaemic infants, large for dates fetuses and delivery problems. For patients who have undergone surgery hoping that their fertility will improve, weight regain can prevent conception and therefore patients should be encouraged to maintain their weight as much as possible. Pregnancy itself causes a significant number of women to gain weight, much of which is not lost after the end of the pregnancy. Women who have previously undergone bariatric surgery should be aware of this side-effect of pregnancy, particularly if they wish to start or continue their family at a later date.

Weight loss is generally shown to restore the hormonal balance in male patients to normal [5, 8]. However there is one interesting case series that has reported complete azospermia in six males following roux-en-y gastric bypass, all previously successful at producing offspring. This study suggested that as a result of surgery, spermatogenesis was altered due to a change in the absorption of the nutrients required for this process [16]. However, no negative impact on sperm quality following surgery was seen in a further study [5], suggesting that there are other confounding factors in this original case series.