Gastric outlet obstruction
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Overview
GASTRIC OUTLET OBSTRUCTION: Pyloric obstruction
Gastric outlet obstruction (GOO,) is the result of any pathology that provides mechanical obstruction to emptying of gastric contents. Two important causes of GOO include: Benign: 37 percent of cases, includes peptic disease Malignant: 53 percent of cases
Anatomy and pathophysiology
Location of the stomach: Left upper quadrant of the abdomen Parts of the stomach: Cardia Body Antrum Pylorus INTRINSIC OBSTRUCTION In GOO, the antrum and pylous are mainly involved. Infiltration, scar formation or inflammation of these structures leads to intrinsic obstruction, resulting in GOO. EXTRINSIC OBSTRUCTION The pylorus extends into the duodenum and is surrounded by the liver, gallbladder and pancreas. Malignancy of any of these neighbouring structures may lead to extrinsic obstruction of the gastric outlet.
History History of PUD or its complications: Indigestion Anorexia nausea, vomiting epigastric pain
History of abdominal pain and weight loss in cases of pancreatic cancer
Clinical presentation: Nausea Vomitting: characteristic feature Intermittent Occurs one hour after ingestion Nonbilious Contains undigested particles of food Intolerance to solids, followed by liquids Dehydration Electrolyte abnormalities
Late stages: Weight loss Malnutrition: more pronounced in patients with malignancy Abdominal distension Features of incomplete obstruction: gastric retention: presenting as early satiety bloating fullness of epigastrium Aspiration pneumonia: due to dilatation of stomach, loss of contractility and accumulation of undigested food contents
Etiology
Benign causes:
Acquired: PUD: 5 % cases ( most commonly affecting pylorus and initial part of the duodenum): Acute- edema and inflammation Chronic- due to intrinsic obstruction as a result of fibrosis and scar formation Gastric polyps Caustic ingestion Obstruction by gallstones (Bouveret syndrome) Complication of acute pancreatitis: pancreatic pseudocyst formation bezoars
Congenital: Pyloric stenosis: most common cause in children more common in boys> girls due to hypertrophy of pyloric circular smooth muscles Congenital duodenal webs
Malignant causes- Malignancies involving neighbouring structures: Pancreas: Pancreatic cancer: most common malignancy leading to extrinsic obstruction of the pylorus, occurs in one fifth of patients Stomach: Gastric cancer Duodenum: Duodenal cancer Ampullary cancer Bile duct: Cholangiocarcinomas Secondary metastases to the gastric outlet by other primaries