Gastric Outlet Obstruction

How it happens

After a meal, the stomach grinds food and pushes it through the pylorus, a muscular valve, into the duodenum. When this channel is narrowed or blocked, food and fluid accumulate in the stomach. The stomach stretches and, eventually, vomiting empties it. Repeated vomiting causes dehydration and loss of acid, potassium and chloride, leading to a characteristic metabolic alkalosis.

Causes

Malignant causes (most common in adults today)

• stomach cancer, especially in the lower stomach
• pancreatic cancer pressing on or invading the duodenum
• cancer of the duodenum, ampulla or bile duct
• lymphoma and metastases

Benign causes

• Peptic ulcer disease: active ulcer swelling or scarring from repeated ulcers near the pylorus. Less common now that H. pylori treatment and acid-suppressing medicines are widely used
• Caustic ingestion with scarring
• Crohn's disease of the stomach or duodenum
• Bezoars: masses of undigested material
• Gallstone ileus (Bouveret syndrome): a gallstone lodged in the duodenum
• Chronic pancreatitis and pancreatic pseudocysts
• Postoperative narrowing after stomach surgery
• Hypertrophic pyloric stenosis: in babies aged 2 to 8 weeks, causing projectile vomiting

Symptoms

• nausea and vomiting, often of undigested food eaten hours earlier, without bile
• early fullness (feeling full after a small amount)
• bloating and upper abdominal discomfort
• weight loss and reduced appetite
• signs of dehydration: thirst, dark urine, dizziness
• a sloshing sound when the belly is moved (succussion splash)
• sometimes visible waves of movement across the upper belly
• symptoms of the underlying cause, such as ulcer pain or jaundice in pancreatic cancer

Gastric outlet obstruction vs gastroparesis

Diagnosis

• blood tests: electrolytes (low potassium and chloride), kidney function, blood count
• nasogastric tube: large volumes of retained fluid support the diagnosis
• CT scan of the abdomen: shows a distended stomach and the site and cause of the blockage
• upper endoscopy: after the stomach is emptied. Shows ulcers, narrowing or tumors and allows biopsies and treatment
• barium studies sometimes
• H. pylori testing for ulcer-related cases

Treatment

Initial care

• nothing by mouth
• a tube through the nose into the stomach to drain it
• IV fluids and correction of potassium and other electrolytes
• IV proton pump inhibitors to reduce acid and ulcer swelling
• nutritional support, sometimes through a feeding tube or IV nutrition

Benign causes

• treat H. pylori and stop NSAIDs
• endoscopic balloon dilation of scarred narrowing, which may need repeating
• surgery (such as pyloroplasty or gastrojejunostomy) if dilation fails

Malignant causes

• endoscopic duodenal stent: a metal mesh tube that holds the channel open, allowing eating within days
• EUS-guided gastroenterostomy: an endoscopic bypass between the stomach and small intestine using a special stent, increasingly used where expertise exists, with longer-lasting results than duodenal stents
• surgical gastrojejunostomy: a bypass operation, often for patients expected to live longer
• treatment of the cancer itself, such as surgery, chemotherapy or radiotherapy

Outlook

Benign obstruction usually responds well to treatment of the ulcer and dilation or surgery. With malignant obstruction, relief of the blockage restores eating and improves quality of life, while overall outlook depends on the cancer.

Frequently asked questions

What are the symptoms of gastric outlet obstruction?

Typical symptoms are vomiting of undigested food hours after eating, early fullness, bloating, upper belly discomfort, loss of appetite and weight loss. Dehydration often follows repeated vomiting.

What causes gastric outlet obstruction?

In adults today, cancer of the stomach, pancreas or duodenum is the most common cause. Scarring from peptic ulcers is the main benign cause. Crohn's disease, bezoars, gallstones and pancreatitis are less common causes.

How is gastric outlet obstruction diagnosed?

Doctors use blood tests to check dehydration and electrolytes, a CT scan to find the blockage, and upper endoscopy to see it directly and take biopsies. Stomach drainage through a nasal tube is usually done first.

Can gastric outlet obstruction be treated without surgery?

Often, yes. Benign narrowing can be stretched with an endoscopic balloon, and malignant blockages can be bypassed with an endoscopic stent or an EUS-guided gastroenterostomy. Surgery is used when these are unsuitable or fail.

Why does vomiting with gastric outlet obstruction contain old food?

Because the blockage stops food from leaving the stomach, meals accumulate for hours or even days. When vomiting occurs, it often brings up recognizable food eaten long before, usually without green bile.