Gastric Outlet Obstruction

Gastric outlet obstruction is mechanical impairment of gastric emptying at the distal stomach, pylorus or proximal duodenum.

Major malignant causes are gastric, pancreatic and duodenal cancer. Benign obstruction is most commonly related to peptic ulcer scarring, although Crohn disease, caustic injury, pancreatitis and postoperative strictures also occur.

Persistent vomiting produces dehydration, chloride and potassium depletion and classically a hypochloraemic, hypokalaemic metabolic alkalosis.

Typical presentation is:

• Progressive postprandial vomiting
• Early satiety
• Epigastric fullness
• Weight loss
• Dehydration

Vomitus often contains food eaten many hours earlier and usually lacks bile when obstruction lies proximal to the ampulla.

Examination may show upper abdominal distension and a succussion splash several hours after eating.

Severe dehydration can produce tachycardia, hypotension, oliguria and acute kidney injury.

Check renal function, sodium, potassium, chloride and bicarbonate before intervention.

CT abdomen with IV contrast: define the obstructing lesion and determine whether malignant disease is locally advanced or metastatic.

Upper gastrointestinal endoscopy with biopsy: establish the cause and provide a route for dilation or stenting where appropriate.

Do not dilate an unexplained gastric outlet stricture before malignancy has been adequately excluded.

Keep fasting and decompress a markedly distended stomach with a nasogastric tube before endoscopy.

Correct extracellular fluid depletion and chloride deficit. 0.9% sodium chloride is appropriate when significant chloride responsive metabolic alkalosis is present. Add potassium only after assessing renal function and urine output.

Benign obstruction

Peptic ulcer related oedema can improve with gastric decompression and potent acid suppression.

A practical regimen is:

Pantoprazole 40 mg IV every 12 hours, changing to oral proton pump inhibition once intake resumes.

Test for and eradicate Helicobacter pylori.

One effective 14 day regimen is:

• Proton pump inhibitor standard dose twice daily
• Bismuth subsalicylate 524 mg orally four times daily
• Tetracycline 500 mg orally four times daily
• Metronidazole 500 mg orally three to four times daily

Confirm eradication after therapy.

A fixed benign pyloric or duodenal stricture can undergo endoscopic balloon dilation, generally in staged sessions rather than aggressive single session expansion. Persistent recurrence despite adequate dilation requires surgery.

Definitive benign surgery may involve pyloroplasty, antrectomy where ulcer pathology warrants resection, or gastrojejunostomy depending on anatomy.

Malignant obstruction

Palliative intervention should restore oral intake with the lowest burden appropriate to expected survival.

Endoscopic self expanding metal stent provides the fastest return to eating and shortest recovery and is particularly useful in patients with poor performance status or expected survival below approximately six months.

Surgical gastrojejunostomy has greater initial procedural burden but better long term patency and is preferable in fit patients expected to survive longer.

Endoscopic ultrasound guided gastroenterostomy is increasingly used in experienced centres because it combines minimally invasive access with a bypass that does not traverse the tumour.

Curable obstructing gastric cancer should undergo oncological treatment rather than purely palliative bypass whenever staging and physiology permit.