Bariatric surgery

From Ganfyd

Surgery aimed at controlling weight. Adjunct to diet and exercise, not magic cure.

Evidence

Reduces mortality and morbidity associated with obesity^[1][2].

• mortality from myocardial infarction reduced by about 50% at 11 years, malignancy reduced by 40%^[3].

• Greatly reduces the rate of type II diabetes ^[4].

Pre-operative Investigations

• Pre-operative upper GI endoscopy - to detect incidental pathology^[5] and to ensure anatomy is suitable (e.g. certain approaches more difficult in the presence of large hiatus hernia).
• Exclude metabolic causes (rare).

A risk score exists.

Surgical Approaches

Essentially, surgery works in one or more ways:

1. Controlled, iatrogenic malabsorption, or
2. Reduced stomach capacitance by reducing the volume available as a reservoir.
3. Changes in physiological response following eating, e.g. dumping syndrome or hormonal effects in some procedures which deliver calories direct to jejunum or ileum.

Historical

Jejunoileal bypass

The stomach, duodenum and a short stretch of jejunum was anastomosed to either the terminal ileum or colon, substantially reducing the absorptive area by bypassing most of the absorptive surface of the jejunum and ileum. The operation was effective, but resulted in increased stool frequency and metabolic abnormalities.

Gastric bypass with loop gastrojejunostomy

The stomach was transected, with the upper half anastomosed to a loop of jejunum. This reduced the reservoir capacity of the stomach and may also have reduced eating due to the unpleasant symptoms of dumping brought on by eating. Reflux from the jejunal loop into the proximal gastric remnant and oesphagus, caused gastritis and oesophagitis.

Horizontal Gastroplasty

The traditional 'stomach stapling'. Effective stomach capacity was reduced by a putting an almost complete horizontal row of staples across the stomach. This created a small proximal reservoir and a small outlet at the corner. Weight gain was frequent.

Current

Adjustable gastric banding

Laparoscopic adjustable gastric band.

Usually performed laparoscopically. A small stomach reservoir is created by a row of vertical staples. The outlet to this reservoir is controlled by a inflatable, adjustable band which is adjustable through a port implanted subcutaneously. The small reservoir results in early satiety and a narrow outlet prolongs this. The texture and, therefore, choice of foods is limited. Initially the patient is restricted to a pureed diet, relaxed after a couple of weeks to mashed.

The advantages are the relative simplicity of the procedure. Little handling of the bowel is required and no anastomoses are performed, with a smaller morbidity and mortality compared to bypass.

Vertical banded gastroplasty

• Slightly better longer term weight loss than banding- about 20%^[6])

Roux-en-Y gastric bypass

Roux-en-Y gastric bypass.

The laparoscopic approach is preferred, but open surgery is sometimes necessary. The upper stomach is transected to form a small stomach pouch, which in turn is anastomosed to jejunum (the Roux loop). The remainder of the stomach, duodenum and a portion of the jejunum is anastomosed to the Roux loop.^[7]

• Results in greatest weight loss, about 30%, ^[8] with benefit only in those with BMI ≥45 kg/m².^[9]

Biliopancreatic diversion (Scopinaro operation; BPD)

A variant of roux-en-y with a distal gastrectomy and common channel of 50cm, with a very long biliopancreatic limb and shorter 200cm alimentary limb. This leaves a very small common area for digestion and absorption of fats. It allows >70% excess weight loss ^[10]; however it has a greater incidence of nutritional complications than roux-en-y ^[11]. Morbidity may be decreased by increasing the common limb length ^[12]

The duodenal switch is a variant of BPD in which a partial gastrectomy is performed, keeping the pyloris intact. It may have improved outcomes as compared to BPD ^[13].

• NICE Guidelines^[14]

Complications

Short Term

• Gallstones - consider ursodeoxycholic acid prevention.^[15]

Long Term

• Vitamin A deficiency ^[16][17]

References