Gastric outlet obstruction

Overview

Gastric outlet obstruction (GOO) is a clinical condition in which there is a blockage at the level of the pylorus or the proximal part of the duodenum, impeding the normal passage of stomach contents into the small intestine. This obstruction can be partial or complete and results in symptoms related to gastric retention, such as nausea, vomiting, and abdominal distension. GOO is not a disease itself but a manifestation of an underlying pathology, which can be benign or malignant. The condition requires timely diagnosis and management to prevent nutritional deficiencies and other complications.

Causes

Gastric outlet obstruction can result from a variety of causes, broadly classified as benign or malignant:

Benign Causes:

• Peptic ulcer disease: Chronic inflammation and scarring near the pylorus can lead to narrowing and obstruction.

• Chronic pancreatitis: Inflammation and fibrosis can compress the duodenum externally.

• Gastric polyps: Large polyps may block the gastric outlet.

• Bezoars: Accumulation of undigested material forming a mass in the stomach.

• Post-surgical adhesions or strictures

Malignant Causes:

• Gastric cancer: Tumors in the antrum or pylorus can cause mechanical obstruction.

• Pancreatic cancer: Especially tumors in the head of the pancreas compressing the duodenum.

• Duodenal cancer or metastatic lesions

Symptoms

The symptoms of gastric outlet obstruction are largely due to impaired gastric emptying and include:

• Persistent vomiting, often containing undigested food from previous meals

• Nausea

• Abdominal bloating and distension

• Early satiety (feeling full quickly)

• Epigastric pain or discomfort

• Weight loss and dehydration

• Visible peristalsis in advanced cases

Symptoms may be intermittent in partial obstruction and become progressively severe as the blockage worsens.

Diagnosis

Diagnosis of GOO involves clinical evaluation, imaging, and endoscopic assessment:

• History and physical examination: Evaluates symptoms and identifies signs of dehydration and malnutrition.

• Abdominal X-ray: May show a dilated stomach with an air-fluid level.

• Upper gastrointestinal (GI) endoscopy: Visualizes the obstruction and allows for biopsy if a malignancy is suspected.

• CT scan of the abdomen: Useful for detecting masses, external compression, and surrounding organ involvement.

• Barium meal study: Highlights delayed gastric emptying and the site of obstruction.

• Laboratory tests: May show electrolyte imbalances (e.g., hypokalemia, hypochloremia) and metabolic alkalosis.

Treatment

Treatment of gastric outlet obstruction depends on the underlying cause and the severity of the condition:

Initial Management:

• Nasogastric decompression: Relieves gastric distension and vomiting.

• Fluid and electrolyte correction: IV fluids to rehydrate and correct metabolic imbalances.

• Nutritional support: May be required through parenteral or enteral routes.

Definitive Treatment:

• Endoscopic balloon dilation: Effective in benign strictures.

• Surgical intervention: Includes vagotomy with pyloroplasty, antrectomy, or gastrojejunostomy, especially in cases of ulcer-related or malignant obstruction.

• Stenting: Endoscopic placement of a self-expanding metallic stent for palliation in inoperable malignancies.

• Oncologic treatment: Chemotherapy or radiation for cancer-related obstruction, if appropriate.

Prognosis

The prognosis of gastric outlet obstruction varies depending on its cause. Benign causes, such as peptic ulcer disease, often have an excellent outcome with appropriate medical or surgical treatment. Malignant causes, on the other hand, tend to carry a poorer prognosis and may require palliative care. Prompt recognition and management can prevent complications such as severe dehydration, electrolyte imbalance, and malnutrition. Long-term follow-up may be necessary to monitor recurrence or progression, especially in malignancy-associated cases.