Gastric outlet obstruction
Gastric outlet obstruction is blockage of the passage from the stomach into the duodenum. The stomach fills and cannot empty. It is a presentation rather than a disease, and the first and most important question is always what is causing it — because the balance of causes has shifted decisively over the past few decades, and malignancy now accounts for the majority of cases in adults.
How it develops
The stomach narrows at the antrum and pylorus, the muscular ring controlling emptying. Obstruction here arises in one of three ways.
Malignant obstruction
Now the commonest cause. A tumour either grows into the lumen or infiltrates the wall, making it rigid and unable to propel contents. The responsible tumours are gastric antral carcinoma, pancreatic cancer of the head invading the duodenum, duodenal or ampullary carcinoma, lymphoma, and metastatic disease involving the region.
Benign peptic obstruction
Once the dominant cause, and now much less common because peptic ulcer disease is usually cured before it reaches this stage. The mechanism has two components, which matters because they respond differently:
- Acute oedema and spasm around an active ulcer — reversible, and improves with acid suppression and eradication
- Chronic fibrotic stricture from repeated cycles of ulceration and healing — fixed scar tissue, which will not respond to medical treatment
Most patients have a mixture of the two, which is why some improve substantially on medical treatment alone and others do not.
Other causes
- chronic pancreatitis, with inflammation and fibrosis in the head of the pancreas compressing the duodenum
- caustic ingestion, producing a dense antral stricture some weeks later
- Crohn's disease of the duodenum
- a large gastric polyp prolapsing through the pylorus
- gallstone obstruction of the duodenal bulb through a cholecystoduodenal fistula — Bouveret's syndrome, a rare variant of gallstone ileus
- previous surgery, with stricture at an anastomosis or adhesions
- adult idiopathic hypertrophic pyloric stenosis, rare
What obstruction does to the body
Persistent vomiting of gastric contents loses hydrogen, chloride, potassium and water, producing a hypochloraemic, hypokalaemic metabolic alkalosis. The kidney, attempting to conserve volume, retains sodium in exchange for hydrogen, and the urine becomes paradoxically acidic despite the systemic alkalosis. This is a genuine trap in management: correction requires normal saline and generous potassium replacement, not bicarbonate, and correcting it before any intervention is not optional. Malnutrition follows quickly, and a chronically obstructed stomach becomes dilated and atonic, which delays recovery even after the obstruction is relieved.
Symptoms
- Vomiting — characteristically large volume, projectile, of undigested food eaten many hours or even a day earlier, and notably not containing bile, because the obstruction lies above where bile enters
- early satiety and a sensation of fullness
- epigastric bloating and discomfort, often relieved by vomiting
- weight loss and dehydration, frequently marked
- a succussion splash — an audible splash on shaking the abdomen more than three hours after eating, indicating a stomach full of retained fluid
- visible gastric peristalsis in thin patients
- lethargy and weakness from electrolyte disturbance
Features suggesting malignancy rather than benign disease: shorter history, older age, pronounced weight loss, anaemia, a palpable mass, jaundice, and the absence of any previous history of ulcer symptoms.
How the diagnosis is made
- Blood tests — electrolytes and blood gas define the metabolic disturbance; anaemia and low albumin indicate chronicity and nutritional depletion.
- Endoscopy is essential and is both diagnostic and potentially therapeutic. The stomach usually requires decompression and washout first. Biopsies must be taken from any stricture, however benign it appears, and repeated if initially negative but suspicion persists, since a malignant stricture may be covered by inflamed but benign-looking mucosa.
- CT of abdomen and pelvis identifies a mass, defines the level, assesses the pancreas, and stages malignancy.
- Endoscopic ultrasound where a submucosal or pancreatic cause is suspected and biopsy is needed.
- Contrast study demonstrates the degree of hold-up and the gastric capacity, and is occasionally useful in planning.
Treatment
First, correct the patient
This deserves emphasis because it is where mistakes are made. Nasogastric decompression, intravenous normal saline with potassium, and correction of the alkalosis come before any procedure. Nutritional assessment and support — enteral where a tube can be passed beyond the obstruction, otherwise parenteral — are started early, since these patients are often profoundly depleted and will not heal an anastomosis otherwise.
Benign obstruction
- Medical treatment — high-dose proton pump inhibitor and H. pylori eradication resolve the oedematous component, and a proportion of patients settle completely.
- Endoscopic balloon dilatation is effective for short fibrotic strictures, often requiring repeated sessions. Perforation is the principal risk.
- Surgery for strictures that fail dilatation. Options are pyloroplasty, gastrojejunostomy (bypassing the obstruction), or antrectomy with reconstruction. Modern practice avoids the extensive acid-reducing operations of the past, since acid is now controlled medically.
Malignant obstruction
Treatment depends on whether the tumour is resectable.
- Resectable disease — resection of the tumour deals with the obstruction as part of curative treatment.
- Unresectable disease — the aim is to restore eating with the least intervention and the shortest recovery, and the choice between the two main options is genuinely individualised:
- Self-expanding metal stent, placed endoscopically. Restores oral intake within a day or two, requires no operation, and is preferred for patients with a short expected survival or who are unfit for surgery. Stent blockage or migration may require reintervention.
- Gastrojejunostomy, joining the stomach to a loop of jejunum beyond the obstruction, performed laparoscopically where possible. Recovery takes longer but the result is more durable, and it is the better option for patients with a longer expected survival.
- Endoscopic ultrasound-guided gastroenterostomy, creating the same bypass endoscopically using a lumen-apposing metal stent, combines the durability of bypass with the recovery of an endoscopic procedure, and is increasingly used in specialist centres.
Where the biliary tree is also obstructed, as is common with pancreatic head tumours, both obstructions are addressed.
Recovery
After stenting, oral fluids usually begin within a day and soft diet within two to three days. After gastrojejunostomy, hospital stay is typically five to eight days. Delayed gastric emptying is common after any treatment, because the stomach has been chronically distended and its muscle has lost tone; it recovers over days to weeks, and patients should be forewarned so that slow initial progress is not taken as failure of the procedure.
A period of small, frequent, soft, low-residue meals is needed in all cases, with dietetic input.
Follow-up
For benign disease, confirmation of H. pylori eradication, repeat endoscopy to confirm healing and patency, and re-biopsy of any persisting abnormality. For malignant disease, follow-up as determined by the oncological plan, with attention to nutrition throughout.
When to seek an opinion
Persistent vomiting of undigested food, particularly with weight loss, needs prompt investigation and should not be treated as simple indigestion. Vomiting with dehydration, weakness or confusion requires emergency assessment, since the electrolyte disturbance can be dangerous in itself.
Common questions
Why am I vomiting food I ate yesterday?
Because the exit from the stomach is blocked, so food cannot pass on into the intestine and accumulates. The fact that the vomit contains recognisable food and no bile points to a blockage at the stomach outlet rather than further down.
Does this mean cancer?
Not necessarily, but it must be excluded properly. In adults, a tumour is now the commonest cause, though scarring from a long-standing ulcer, inflammation of the pancreas and other benign conditions also cause it. An endoscopy with samples taken from the narrowed area is how the question is answered, and it is worth having done promptly.
Can it be opened up without an operation?
Often, yes. A narrowing from ulcer scarring can be stretched with a balloon at endoscopy, sometimes more than once. A blockage from a tumour that cannot be removed can be relieved by placing a metal tube, or stent, across it, which usually allows eating again within a day or two.
Why do I need drips before anything is done?
Because prolonged vomiting loses large amounts of fluid and salts, particularly chloride and potassium, and disturbs the acid balance of the blood. Correcting this first makes any procedure considerably safer, and it usually also makes you feel a good deal better.
Will I be able to eat normally afterwards?
Most people eat well again, but not immediately. A stomach that has been stretched and blocked for weeks takes time to regain its muscle tone, so emptying can be slow at first. Small, frequent, soft meals for a few weeks are the usual advice, and progress is gradual rather than instant.
Stent or bypass operation — which is better?
It depends on your situation rather than on one being generally superior. A stent works quickly, involves no operation and suits those who are frail or whose outlook is measured in months. A bypass operation takes longer to recover from but lasts better, and is usually preferred when the expected outlook is longer.
Could this have been prevented?
Where it is caused by ulcer scarring, yes — treating the infection and stopping anti-inflammatory tablets prevents the repeated ulceration that produces the scar. Where it is caused by a tumour, it is usually the first sign of the problem rather than something that could have been headed off.
Related conditions
Other conditions of the stomach covered on this site:
- Peptic ulcer disease
- Perforated and bleeding peptic ulcer
- Gastric polyps
- Gastrointestinal stromal tumour (GIST)
- Gastric neuroendocrine tumours (gastric carcinoids)
- Stomach cancer (gastric cancer)
This page provides general information and does not replace an individual medical consultation. Assessment and treatment are decided for each patient after review of their history, examination and investigations.