Duodenal obstruction

Duodenal obstruction in the adult is usually due to malignancy, and cancer of the pancreas is the most common cause. About one-third of patients with pancreatic cancer treated by endoscopic stenting will develop obstruction. Treatment is by gastroenterostomy. In patients having a surgical biliary bypass for pancreatic cancer gastric drainage may be necessary.

A variety of other malignancies can cause duodenal obstruction including metastases from colorectal and gastric cancer. Primary duodenal cancer is much less common as a cause of obstruction than these other malignancies.

Annular pancreas may rarely cause duodenal obstruction. Obstruction usually follows an attack of pancreatitis and on occasions the obstruction may be mistaken for malignancy. Arteriomesenteric compression is an ill-defined condition in which it is proposed that the fourth part of the duodenum is compressed between the superior mesenteric artery and the vertebral column. Where it is convincingly demonstrated and causing weight loss duodenojejunostomy may be performed. 

Gastroplasty for morbid obesity

A number of surgical treatments has been devised for morbid obesity, but of these the most commonly used is the vertical banded gastroplasty (Mason). Some surgeons prefer a gastric bypass operation which has some similarities. Indeed, gastric bypass can be used as a revisional procedure following stomal obstruction, one of the more common complications of gastroplasty. 

Indications for operation

Selection of patients for operation should ideally be made by a team that includes a nutritionist/endocrinologist and a psychiatrist, as well as a surgeon, as it is important that major metabolic problems and severe psychiatric disorders are elucidated before operation. The patient should be 100 per cent over their ideal weight for height or have a body mass index [weight (kg)/height (in)2] of greater than 45. This figure is selected because the increase in morbidity and mortality at this level of obesity is excessive. Very often the patient will have some of the morbidity associated with severe obesity such as hypertension, diabetes or osteo­arthritis. Preoperative counselling should include discussion of the possibility of perioperative mortality (which is in the region of 1—4 per cent). This is very much an elective procedure and the patient is at risk of postoperative respiratory problems and pulmonary thrombo­embolism. Intensive or high-dependency care facilities must be available. 

Operation

The operation is performed under general anaesthesia and the addition of an epidural greatly aids both the perioperative and postoperative management. The procedure should be undertaken by an anesthetist very experienced in this area.

The abdomen is opened from the midline incision and adequate retraction provided to gain access to the upper part of the stomach. Approximately 50 per cent of patients will already have gallstones and, if this is the case, cholecystectomy should be carried out. Some surgeons advocate prophylactic cholecystectomy but this is difficult to substantiate. A large orogastric tube is placed in the stomach and the lesser sac is opened through the greater omentum by careful blunt dissection. A window is made between the lateral side of oesophagus and the lesser sac (Fig. 51.35). It is important to take great care during this part of the operation to avoid damaging the spleen or short gastric arteries. Once this has been carried out it is convenient to place a tape through this window to avoid losing access. A position is selected on the anterior wall of the stomach above the level of the incisura. A circular stapler with the head removed and the spike inserted is placed in the lesser sac with edge of the instrument up against the tube in the stomach. The handle of the stapler is then rotated to introduce the spike through the front and back wall of the stomach. Once this has been done the spike can be removed and the anvil of the stapler inserted in the usual fashion. Tightening up and firing the stapler produces a stapled circular defect in the mid body of the stomach with the space about 15 mm between the lesser curve and the window. Following this a stapler, such as the Auto suture TA90B, is inserted through the circular window and through the gap made at the lateral side of the oesophagus. This instrument is particularly recommended as it places four rows of staples in the stomach (Fig. 51.35) which greatly reduces the possibility of staple line disruption. These manoeuvres lead to the creation of a pouch of about 30 ml, the volume being checked before the linear stapler is fired. It is then important to band the outlet of this pouch to avoid dilatation with time. A number of materials may be used including polypropylene mesh and expanded polytetrafluoroethylene (PTFE). Whatever material is used, the width should be approximately 1.5 cm and the circumference of the band about 5 cm. It has been shown in a variety of studies that if the band has a larger circumference than this there is a high incidence of inadequate weight loss, and if it made as small as 4.5 cm there is a high incidence of stomal stenosis. The exact dimensions of the band, however, are a critical part of the operation and the experience of the surgeon will often subtly alter the band circumference.

Postoperatively the patients should be managed on an intensive care or a high-dependency care unit until the possibility of apnoea and other complications is diminished. Epidural anaesthesia is useful as it avoids the amount of opiate given to the patient. The patient may be introduced to fluids on the first postoperative day and small quantities of food around the fourth or fifth day. Dietary advice is very important at this point. It is important that the patient understands that liquidized food or high-calorie supplements ate to be avoided and that only small quantities of food are to be eaten to avoid blocking the narrow pouch outlet.

Patients can be expected to lose between a third and a half of their body weight in the 2 years following operation. Over this period it is advisable to take a vitamin supplement to avoid deficiencies which may otherwise occur. Following the first 2 years it is possible for the patient to begin weight gain, and it is important that they understand that moderation and self-control will be necessary in the long term. This is often possible because after 2 years the patient’s eating habits have been quite radically changed and the apparently insurmountable task of losing almost a half of their body weight has been overcome. 

Complications

Pulmonary embolism is a risk for all such patients and hence they should be managed with adequate doses of prophylaxis (5000 units of heparin tid). Although it might be expected that wound herniation would be a common sequel of this operation, in practice if the abdominal wound is repaired well with a continuous nonabsorbable suture such problems are uncommon. As with any procedure that involves opening the gastrointestinal tract, prophylactic antibiotics are important. Unlike small bowel bypass, vertical banded gastroplasty is not associated with major metabolic consequences or liver disease. The two commonest long-term complications are inadequate weight loss, which usually relates either to technical aspects of the procedure or to patient noncompliance, and stomal stenosis which may occur if the band is too tight or if fibrosis occurs in this region. The former complication can be dealt with only by revisional surgery. Stomal stenosis can be treated endoscopically by balloon dilatation, although very often this is unsuccessful in the long term.