Gastric outlet obstruction: symptoms, causes and treatment

The stomach empties into the first part of the small bowel (the duodenum) through a muscular valve called the pylorus. If this exit is narrowed or blocked, the stomach cannot empty. A 2025 review in the medical literature describes gastric outlet obstruction (GOO) as a clinical syndrome characterised by mechanical blockage at the level of the pylorus or proximal duodenum, leading to vomiting after meals, upper abdominal pain and early satiety, with chronic gastric distension and malnutrition often following when emptying is impaired.

GOO is different from gastroparesis, in which the stomach empties slowly because of poor muscle or nerve function rather than a physical blockage. The distinction matters because the investigations and treatment differ.

NHS inform lists the symptoms of gastric outlet obstruction, in the context of a stomach ulcer, as follows. The 2025 review adds nausea and describes the vomiting as postprandial, meaning after eating, with malnutrition and gastric distension as consequences of long-standing obstruction.

• Vomiting large amounts of undigested food.

• A constant feeling of bloating or fullness.

• Feeling more full than usual after eating less food.

• Unexplained weight loss.

• Nausea and upper abdominal pain, according to the 2025 review.

The NHS stomach ulcer page lists, among reasons to ask for an urgent GP appointment or get help from NHS 111, tummy pain that is getting worse or does not go away, loss of appetite, feeling full after a very small amount of food, weight loss without trying, feeling as if there is a lump in the tummy, trouble swallowing, being sick repeatedly and feeling tired all the time.

It says to call 999 or go to A&E if you are vomiting bright red blood or your vomit looks like ground coffee, your poo has blood in it or is black, sticky and very smelly, you have severe tummy pain, it is painful to touch your tummy or you have chest pain that started suddenly. Persistent vomiting with inability to keep fluids down needs same-day assessment because of the risk of dehydration; this is general medical advice rather than a statement from the cited pages.

NHS inform explains that an inflamed (swollen) or scarred stomach ulcer can obstruct the normal passage of food. The NHS says the main causes of stomach ulcers are infection with Helicobacter pylori and regular use of anti-inflammatory painkillers such as ibuprofen, with smoking and older age increasing the risk.

The 2025 review explains that peptic ulcer disease was historically the commonest cause but its incidence has declined thanks to H. pylori eradication and proton pump inhibitors, and that malignant causes now account for 50 to 80% of cases in many regions. It lists pancreatic cancer (50 to 60% of malignant cases in the figures it cites), gastric cancer (about 35%) and less frequently duodenal cancer, cholangiocarcinoma and metastatic disease. Because cancer is a leading cause, a new obstruction in an older adult is always investigated.

NHS inform says an endoscopy can be used to confirm the obstruction. The NHS stomach ulcer page describes tests a GP may arrange for ulcer symptoms, including breath or stool tests for H. pylori and, where needed, referral for a gastroscopy. Imaging such as CT may be used, particularly where cancer is suspected, and a biopsy is taken at endoscopy from any suspicious area.

Blood tests are often done to check hydration, salts such as potassium, and nutritional status, because prolonged vomiting can upset them. These details are general clinical practice rather than statements from the pages cited.

NHS inform says that if the obstruction is caused by inflammation, proton pump inhibitors (PPIs) or H2-receptor antagonists can be used to reduce stomach acid levels until the swelling goes down. If it is caused by scar tissue, surgery may be needed, which can involve passing a small balloon through an endoscope and inflating it to widen the site of obstruction.

For blockages caused by cancer, the 2025 review describes endoscopic stenting and endoscopic ultrasound-guided gastroenterostomy as options, and surgical gastrojejunostomy (a bypass connecting the stomach to the small bowel), with surgery providing more durable palliation. It says the choice depends on the patient's condition, the tumour and available expertise, and reports a national study in which 68.4% of 8186 patients with GOO had endoscopic stenting and 31.6% had gastrojejunostomy.

Supportive care, including fluids and nutrition, is part of treatment while the obstruction is dealt with; the details are individual and decided by the hospital team.

The outlook depends mainly on the cause. A blockage from an ulcer scar can often be relieved and the underlying ulcer treated; a blockage from cancer is part of a wider cancer treatment plan, and the 2025 review frames the goal in advanced disease as symptom relief and improving quality of life.

In the NHS the route is generally GP or emergency department, then hospital gastroenterology and surgical teams, with a cancer multidisciplinary team where relevant. Private care offers endoscopy and specialist consultation, but urgent obstruction with vomiting and dehydration is usually dealt with through emergency pathways.