Gastric Outlet Obstruction

Gastric Outlet Obstruction (GOO)

Introduction to Gastric Outlet Obstruction

Definition: Gastric Outlet Obstruction (GOO) is a clinical syndrome resulting from diseases that impede gastric emptying.
Symptoms: Includes abdominal pain, postprandial vomiting, early satiety, and weight loss.
Location of Obstruction: May occur at the distal stomach, pyloric channel, or duodenum. The obstruction can be intrinsic or extrinsic to the stomach.

Etiology of GOO

Mechanical Obstruction:
- Benign Causes: Peptic ulcer disease, NSAID use, H. pylori inflammation, polyps, corrosive substance ingestion, gastric tuberculosis, anastomotic strictures, Crohn disease, gastric bezoars, gastric volvulus, eosinophilic gastroenteritis.
- Malignant Causes: Most commonly pancreatic cancer, followed by ampullary, duodenal, and gastric cancers.
Motility Disorders: Contributing to the obstruction but not mechanical in nature.

Clinical Consequences of GOO

Acute and Chronic Phases: Characterized by continuous vomiting, leading to dehydration and electrolyte abnormalities.
Progression: Persistent obstruction can cause gastric dilatation, loss of stomach contractility, and risk of aspiration pneumonia due to undigested food accumulation.

Treatment Approaches

General Strategy: Treatment depends on the underlying cause, and it can be surgical or medical.
Surgical Intervention: Indicated for significant obstruction or failure of medical therapy. Options include endoscopic balloon therapy and surgery.
Medical Management: Primary approach for benign causes, surgery is a last resort after medical management and endoscopic dilation fail.
Management of Malignant GOO: Aims to improve symptoms and restore oral diet tolerance.

Epidemiology of Gastric Outlet Obstruction (GOO)

Historical Perspective

In the past, peptic ulcer disease (PUD) was the predominant benign cause of GOO, accounting for up to 90% of cases.
In 1990, GOO was estimated to occur in 5% to 10% of all hospital admissions for ulcer-related complications.

Shift in Causes

With the advent of treatments like Helicobacter pylori eradication and the widespread use of proton pump inhibitors (PPIs), the landscape of GOO causes has shifted.
Currently, benign causes, particularly duodenal ulcers, account for fewer than 5% of cases.

Recent Trends

A retrospective study conducted between 2006 and 2015 sheds light on the contemporary scenario.
In this study, 38% of GOO cases were attributed to malignancies, while 62% were linked to benign factors.

Etiology

Gastric outlet obstruction (GOO) is a clinical syndrome characterized by impediments in gastric emptying, attributed to either mechanical obstruction or motility disorders. The etiology of GOO encompasses two broad categories: mechanical obstruction and motility disorders.

Mechanical Obstruction:

Mechanical obstruction can arise from various factors, including both benign and malignant conditions.
Benign causes encompass peptic ulcer disease, nonsteroidal anti-inflammatory drug (NSAID) usage, Helicobacter pylori-related inflammation, polyps, ingestion of corrosive substances, gastric tuberculosis, anastomotic strictures, Crohn’s disease, gastric bezoars, gastric volvulus, and eosinophilic gastroenteritis.
Peptic Ulcer Disease
- Once the most common cause of GOO
- Incidence has declined with the discovery of Helicobacter pylori and the introduction of proton pump inhibitors
Crohn’s Disease
- Clinically significant gastroduodenal Crohn’s disease is uncommon, occurring in fewer than 5 percent of patients
- When present, about 60 percent of patients have continuous disease involving the antrum, pylorus, and proximal duodenum
- Obstruction due to Crohn’s-related strictures is the most common complication of gastroduodenal disease

Malignant Causes:

Pancreas Adenocarcinoma: Malignant conditions are often responsible for mechanical obstruction in GOO cases. Fifteen to 25 percent of patients with pancreatic cancer present with GOO.
Gastric Cancer: Distal gastric cancer remains a relatively common cause of malignant GOO, accounting for up to 35 percent of GOO.
Other Causes
- Gastric lymphoma
- Large neoplasms of the proximal duodenum and ampulla
- Local extension of advanced gallbladder carcinoma or cholangiocarcinoma
- Metastatic or primary malignancy in the duodenum
- Gastric carcinoid

Clinical Presentation of Gastric Outlet Obstruction (GOO)

Gastric outlet obstruction (GOO) is a clinical syndrome characterized by a range of symptoms, each contributing to its diagnostic complexity.

Key Symptoms:

Abdominal pain
Postprandial vomiting
Early satiety
Weight loss

Prominent Symptoms:

Nausea and vomiting are cardinal symptoms of GOO. Vomiting often contains undigested food particles.
In the early stages, vomiting may be intermittent and typically occurs within 1 hour of a meal.
Patients with GOO may also experience symptoms of gastric retention, including early satiety, bloating or epigastric fullness, indigestion, anorexia, nausea, vomiting, epigastric pain, and weight loss.
Weight loss tends to be more frequent as the condition becomes chronic, with significant weight loss often observed in patients with malignant disease.
Abdominal pain is less frequent and is typically linked to the underlying cause, such as peptic ulcer disease or pancreatic cancer.

Recognizing these diverse symptoms and their progression is crucial for early diagnosis and the effective management of GOO.

Diagnostic Tests for Gastric Outlet Obstruction

Laboratory Studies

Complete Blood Count (CBC): Used to check for anemia.
Electrolyte Panel: Identifies and corrects any electrolyte abnormalities.
Liver Function Tests: Particularly relevant when a malignant etiology is suspected.
Helicobacter Pylori Test: Conducted when peptic ulcer disease is a suspected cause.

Imaging Studies

Plain Abdominal Radiography: Basic imaging technique for initial assessment.
Contrast Upper Gastrointestinal (GI) Studies: Involves using Gastrografin or barium for detailed imaging.
Computed Tomography (CT) with Oral Contrast: Provides comprehensive visualization of the gastric anatomy.

Diagnostic Procedures

Upper Endoscopy: Primary tool for visualizing the gastric outlet and obtaining tissue diagnosis.
Sodium Chloride Load Test: Involves infusing 750 mL of sodium chloride solution into the stomach; more than 400 mL remaining after 30 minutes indicates GOO.
Nuclear Gastric Emptying Studies: Measures the passage of orally administered radionuclide to assess gastric emptying time.

Optimal Diagnostic Approach

Esophagogastroduodenoscopy (Upper Gastrointestinal Endoscopy): Considered the best test for diagnosing GOO. This procedure involves using a long, flexible tube with a camera to directly visualize the gastric outlet and potentially obtain tissue samples.

Differential Diagnosis

The differential diagnosis for gastric outlet obstruction (GOO) includes a variety of conditions that can cause similar symptoms. These conditions can be broadly categorized into gastrointestinal disorders, metabolic disorders, and neurological disorders.

Gastrointestinal Disorders

These include:

Peptic ulcer disease
Gastric cancer
Gastric polyps
Gastric volvulus
Crohn’s disease
Gastric bezoars

Metabolic Disorders

These include:

Hypercalcemia
Hypokalemia
Uremia

Neurological Disorders

These include:

Parkinson’s disease
Diabetic gastroparesis
Myotonic dystrophy

It’s important to note that the exact differential diagnosis will depend on the individual patient’s symptoms, medical history, and the results of diagnostic tests. A thorough evaluation is necessary to accurately diagnose the cause of the symptoms and to rule out other potential conditions.

Treatment for Gastric Outlet Obstruction (GOO)

Conservative Management

For benign causes such as peptic ulcer disease, initial treatment often involves conservative management. This includes:

General Measures:

Patients suspected of having GOO should be made nothing per os (NPO).
Adequate fluid and electrolyte replacement is essential.
Placement of a nasogastric tube for gastric decompression is recommended.
Parenteral Proton Pump Inhibitors: Regardless of the underlying cause, parenteral proton pump inhibitors are suggested as they reduce gastric secretions and address inflammatory aspects of GOO.
Avoidance of nonsteroidal anti-inflammatory drugs (NSAIDs)
Testing for and treating Helicobacter pylori

If these measures fail, endoscopic dilation or surgery may be attempted.

Endoscopic Treatments

Endoscopic treatments include:

Balloon dilation
Placement of self-expandable stents
Endoscopic ultrasound-guided gastroenterostomy (EUS-GE)

Surgical Interventions

Surgical interventions can include procedures such as:

Vagotomy and antrectomy
Vagotomy and pyloroplasty
Gastrojejunostomy

The choice of surgical procedure depends upon the patient’s particular circumstances.

Malignant Obstruction

In cases of malignant obstruction, the extent of surgical intervention for the relief of GOO is weighed against the malignancy’s type and extent. Endoscopic stenting is an effective, minimally invasive treatment for patients with malignant GOO and poor prognosis, allowing resumption of oral intake and improving quality of life.

Benign Obstruction:

Peptic Ulcer Disease (PUD):

Conservative measures are often attempted initially, including:
- Acid suppression
- Avoidance of nonsteroidal anti-inflammatory medications
- H. pylori eradication when applicable
Medical therapy may involve nasogastric tube suction, IV proton pump inhibitors, and parenteral nutritional supplementation.
A trial of medical therapy typically spans three to seven days, followed by reevaluation.
Endoscopic therapy is an option, particularly in recent studies.
Surgical intervention is considered if conservative measures fail.

Chronic Pancreatitis:

Chronic pancreatitis-related GOO typically requires surgery, with limited data on conservative approaches.

Pancreatic Pseudocyst:

Various options exist for managing GOO resulting from large pancreatic pseudocysts, including:
- CT-guided percutaneous drain placement
- Transpapillary endoscopic drainage
- Endoscopic cyst gastrostomy or duodenostomy
- Surgical internal drainage
Treatment choice depends on the specific circumstances.

Crohn’s Disease:

Management approaches for GOO in Crohn’s disease encompass medical, endoscopic, and surgical interventions.
Medical treatment may involve acid suppression, H. pylori eradication, and corticosteroids.
Endoscopic balloon dilation may be attempted but often requires repeated sessions.
Surgery becomes necessary for some patients with frequent symptoms.

Caustic Ingestion:

Traditionally, surgery has been the preferred treatment for GOO resulting from corrosive agent ingestion.
Temporary interventions during the subacute phase may include gastrostomy or feeding jejunostomy.
Endoscopic balloon dilation has shown limited success in select cases.

Bouveret’s Syndrome:

This condition usually requires surgical intervention to remove the impacted gallstone, repair the fistula, and possibly remove the gallbladder.
Endoscopic removal after stone disruption via extracorporeal shockwave lithotripsy is an alternative.

Large Gastric Polyps:

GOO due to large gastric polyps can often be treated endoscopically.

Gastric Bezoars:

Treatment options for gastric bezoars encompass medical, endoscopic, and surgical approaches, depending on the specific situation.

The prognosis of gastric outlet obstruction (GOO) depends on the underlying cause.

Benign causes:
- Early surgery is recommended for patients with GOO secondary to chronic peptic ulcer disease (PUD).
- Without surgery, there is a high likelihood of recurrent obstruction, hemorrhage, and perforation.
Malignant causes:
- Generally poor prognosis compared to other causes of GOO.
- Due to advanced stage of the disease at diagnosis and poor prognosis of the underlying malignancies.
Long-term prognosis:
- A retrospective study found that 92% of patients who lived for more than 3 years after their presentation with GOO due to peptic ulcer required surgery for relief of obstruction.
- Conservative management may be initially attempted, but most patients eventually require surgical intervention for definitive treatment.