Over the past decade, following the publication of several long-term outcome studies that showed a significant improvement in cardiovascular risk and mortality after bariatric surgery, the number of bariatric procedures being carried out annually in the UK has grown exponentially. Surgery remains the only way to produce significant, sustainable weight loss and resolution of comorbidities. Nevertheless, relatively few surgeons have developed an interest in this field. Most bariatric surgery is now performed in centres staffed by surgeons with a bariatric interest, usually as part of a multidisciplinary team.
The commonest weight loss procedures performed around the world at present are the gastric band, the gastric bypass and the sleeve gastrectomy. In very obese patients, an alternative operation is the duodenal switch, while the new ileal transposition procedure represents one of the few purely metabolic operations designed specifically for the treatment of type II diabetes. Older operations such as vertical banded gastroplasty and jejuno-ileal bypass are now obsolete, although patients who have undergone such procedures in the distant past may still present to hospital with complications. The main endoscopic option at present is insertion of a gastric balloon, with newer procedures like the endoscopic duodenojejunal barrier and gastric plication on the horizon. Implantable neuroregulatory devices (gastric ‘pacemakers’) represent a new direction for surgical weight control by harnessing neural feedback signals to help control eating.
It should be within the capability of any abdominal surgeon to manage the general complications of bariatric surgery, which include pulmonary atelectasis/pneumonia, intra-abdominal bleeding, anastomotic or staple-line leak with or without abscess formation, deep vein thrombosis (DVT)/pulmonary embolus and superficial wound infections. Patients may be expected to present with malaise, pallor, features of sepsis or obvious wound problems. However, clinical features may be difficult to recognise owing to body habitus. Abdominal distension, tenderness and guarding may be impossible to determine clinically due to the patient’s obesity. Pallor is non-specific. Fever and leucocytosis may be absent. Wound collections may be very deep. These complications in a bariatric patient should be actively sought with appropriate investigations. In particular, it is vital for life-threatening complications such as bleeding, sepsis and bowel obstruction to be recognised promptly and treated appropriately. A persistent tachycardia may be the only sign heralding significant complications and should always be taken seriously. It is useful to classify complications as ‘early’, ‘medium’ and ‘late’ because, from the receiving clinician’s point of view, the differential diagnosis will differ accordingly.
Complications of bariatric surgery presenting to the GENERAL SURGEON
The SURGEON 
[…] the surgery for other reasons. Patients with NASH cirrhosis are at potentially higher risk for surgical complications, although some centers have demonstrated encouraging results with sleeve gastrectomy in patients […]