How would you describe gastric outlet obstruction?

Gastric Outlet Obstruction: Clinical Description

Gastric outlet obstruction (GOO) is a clinical syndrome characterized by mechanical obstruction at the level of the pylorus, distal stomach, or duodenum, resulting in impaired gastric emptying and manifesting with postprandial vomiting, nausea, early satiety, epigastric pain, abdominal distension, and progressive weight loss. 1, 2, 3

Pathophysiology and Mechanism

• GOO represents a mechanical blockage that prevents normal passage of gastric contents into the small intestine, distinct from functional disorders like gastroparesis where motility is impaired without anatomic obstruction 1, 4
• The obstruction occurs when tumor compression, infiltration, or cicatricial stricturing physically narrows the gastric outlet to a degree that prevents adequate emptying 2, 3
• This mechanical nature is critical to distinguish from gastroparesis, which presents with symptomatic delayed gastric emptying in the absence of mechanical obstruction 1

Clinical Presentation

Cardinal Symptoms

• Postprandial vomiting is the hallmark symptom, often containing undigested food from meals consumed hours earlier 5, 2
• Early satiety and epigastric fullness develop as the stomach becomes chronically distended proximal to the obstruction 1, 3
• Progressive weight loss results from inadequate oral intake and severe malnutrition 2, 6
• Nausea, bloating, and upper abdominal pain are common associated symptoms 1, 7

Physical Examination Findings

• Abdominal distension may be visible, particularly in the epigastric region 5
• Visible peristalsis can sometimes be observed through the abdominal wall as the stomach attempts to overcome the obstruction 5
• Succussion splash (a sloshing sound heard on auscultation while rocking the patient) indicates retained gastric contents 5
• Signs of dehydration and malnutrition may be evident in advanced cases 2

Etiologic Classification

Malignant Causes (Most Common in Adults)

• Malignancy now accounts for approximately 60% of adult GOO cases, representing a dramatic shift from historical patterns 4, 8
• Locally advanced pancreatic cancer (particularly head of pancreas) is one of the two most frequent malignant causes, causing extrinsic compression or direct duodenal invasion 1, 8
• Antral gastric adenocarcinoma represents the other most common primary malignancy, accounting for approximately 15% of all GOO cases 8
• Symptomatic GOO occurs in 10% to 25% of patients with pancreatic cancer 1
• Other malignant causes include duodenal/ampullary neoplasms, gastric lymphoma, and peritoneal carcinomatosis 4, 8, 3

Benign Causes (Now Less Common)

• Cicatrizing chronic duodenal ulcer was historically the most common cause but has dramatically decreased with widespread use of H2 blockers and proton pump inhibitors 4
• Crohn's disease with stricture formation can cause obstruction 4
• Other benign causes include endometriosis and caustic ingestion sequelae 4

Critical Diagnostic Distinction

A crucial pitfall is failing to distinguish mechanical GOO from functional gastroparesis, as these conditions require entirely different management approaches despite similar symptomatology 1, 4. Gastroparesis is defined as symptomatic delayed gastric emptying occurring in the absence of mechanical obstruction, with failure of antral contractions and/or pyloric relaxation rather than anatomic blockage 1. This distinction must be made through imaging (CT scan) and endoscopy to visualize whether a mechanical obstruction exists 5, 8.

Impact on Patient Outcomes

• GOO significantly impacts both survival and quality of life in patients with advanced malignancies 2, 9
• Patients often present with intractable vomiting and severe malnutrition, which further compromise therapeutic options 2
• The condition leads to decreased oral intake, dehydration, electrolyte abnormalities, and progressive debilitation 5, 7
• Without intervention, GOO results in complete inability to maintain adequate nutrition, necessitating prompt palliative or definitive treatment 2, 6