Gastric Outlet Obstruction - Causes, Symptoms, Diagnosis, and Treatment

Introduction

The human digestive system works sequentially while digesting food. The food in the stomach undergoes various absorption steps and reaches the small intestine through a pyloric sphincter - a muscle that connects the stomach and the small intestine and controls the passage of food, stomach fluids, etc.

The obstruction hampers the food emptying process from the stomach to the small intestine. This is a rare condition more commonly seen in males than females. The nature of the obstruction causing disease or condition can be benign or malignant. In general, surgical treatment is recommended to treat patients with gastric outlet obstruction.

What Is Gastric Outlet Obstruction (GOO)?

It is a syndrome resulting from a mechanical obstruction or impediment in the food emptying process from the stomach to the small intestine - gastric emptying.

What Is Malignant Gastric Outlet Obstruction?

It is a clinical condition in which mechanical obstruction is caused by the presence of a tumor in the pylorus or duodenum.

What Are the Causes of Gastric Outlet Obstruction?

The causes of gastric outlet obstruction are as follows:

Mechanical obstruction can be benign or malignant. The benign causes of gastric outlet obstruction are:

• Peptic Ulcer Disease - Sore formation on the lining of the esophagus, stomach, or small intestine.

• Nonsteroidal Anti-inflammatory Drugs- a therapeutic drug class that reduces pain, inflammation, fever, and prevents blood clots

• Polyps - An abnormal overgrowth of tissues that look like tiny mushroom stalks.

• Gastric Tuberculosis - Rare tuberculosis of the stomach, associated with pulmonary tuberculosis.

• Consumption of Corrosive Substances - Reactive substances or chemicals that cause injuries to the esophagus and stomach.

• Gastric Volvulus - Abnormal twisting of the stomach or its parts.

• Crohn’s Disease - Incurable inflammation of the bowel.

• Gastric Bezoars - A foreign body, such as a hard mass in the stomach when ingested substances accumulate in the stomach.

• Annular Pancreas - A birth defect in the pancreas. An extra ring is present surrounding the duodenum.

• Pancreatitis - Inflammation of the pancreas.

• Eosinophilic Gastroenteritis - It is a rare disorder caused by inflammation of the stomach and small intestine.

• Bouveret Syndrome - Obstruction in the gastric outlet caused by a gallstone in the distal part of the stomach.

• Anastomotic Strictures - It is the narrowing of the connection between the stomach and small intestine.

The malignant cause can be cancer or tumor. Most commonly, distal gastric cancer causes up to 35 % of gastric outlet obstruction cases.

Motility Disorder- Abnormal contractions in the gastrointestinal tract due to muscle spasms. The most common cause of gastric outlet obstruction is gastroparesis (a type of motility disorder in which the normal muscle movement of the stomach is affected).

Where Is Gastric Outlet Obstruction Located?

It can be present in the distal stomach (the lowest two parts - antrum and pylorus), the pyloric canal (junction between the stomach and duodenum), or the duodenum.

What Is the Most Common Cause of Gastric Outlet Obstruction in Adults?

Peptic ulcers and malignancy are the most common causes of gastric outlet obstruction.

What Is the Most Common Cause of Gastric Outlet Obstruction in Neonates?

Hypertrophic pyloric stenosis is the most common cause of gastric outlet obstruction in neonates. It is a condition of thickening of the opening or junction between the stomach and small intestine.

What Are the Symptoms of Gastric Outlet Obstruction?

The symptoms of gastric outlet obstruction depend on the underlying disease or cause. In general, the symptoms are:

• Nausea and vomiting are the most common symptoms.

• Loss of appetite due to a feeling of loss of hunger and/or thirst - early satiety.

• Feeling of fullness in the stomach due to gas-bloating.

• Loss of weight.

• Malnutrition.

• Pain in the stomach.

How to Diagnose Gastric Outlet Obstruction?

1. Physical Examination: The patient will have weight loss upon examination. Hypovolemia is also present - decreased flow of blood into the heart, leading to organ failure. A sloshing sound is heard from the stomach movement with a stethoscope. This sound can be heard during a sudden movement of the patient or the stomach. If the suction splash is present after eating food or meal by the patient, then it indicates gastric outlet obstruction. An abnormally swollen stomach may be present - abdominal distension.

2. Patient’s Medical History: The patient may give a history of taking nonsteroidal anti-inflammatory drugs, Aspirin, Opioids, or Anticholinergics. These medications may cause gastric outlet obstruction.

3. Blood Test: It may show lower levels of potassium (hypokalemia) and lower levels of chloride (hypochloremic alkalosis). Increased levels of serum gastrin are present.

4. Imaging Tests: X-ray may show the presence of air bubbles in the swollen or distended stomach. Sometimes, the small bowel is not visible in the X-ray, indicating the large size of the obstruction. Barium or water-based contrast may fail to get through the small bowel, indicating full obstruction. Computed tomography provides detailed information on the thickened pylorus or gastric wall and the presence of lymph nodes.

5. Endoscopy: It is done to confirm the cause of the obstruction. A thin tube with a camera is inserted into the stomach through the esophagus, and the internal structures, abnormalities, lesions, etc., are visualized on a screen or monitored by the doctor.

6. Saline Load Test: In this test, 750ml of saline is injected into the patient’s stomach with the help of a nasogastric tube. After 30 minutes, with the help of a needle, the fluid is pulled back or taken out (aspiration). If more than 400ml of fluid comes out, it suggests positive aspiration.

How to Treat Gastric Outlet Obstruction?

If the gastric outlet obstruction is caused by a benign disease or condition, then the treatment includes:

Conservative Approach:

1. Acid suppression should be done - a process of reducing the formation of acid in the stomach with the help of medications and proton pump inhibitors.

2. If the patient is taking nonsteroidal anti-inflammatory drugs, Aspirin, Opioids, or Anticholinergics, then these must be stopped immediately.

Surgical Approach:

1.Endoscopic Balloon Dilation (EBD):

• Endoscopy is performed to see the abnormality or the obstruction. A stricture - a scar restricting the flow of fluids - is also identified.

• After identifying the obstruction, the doctor inserts a balloon dilator with the help of a guidewire.

• The structure of the scarring extent decides the dilation to be done. If the stricture is narrow, then dilation should be performed in various steps. For example, strictures with a small diameter require more dilation. A dilation of up to 15 mm is suggested.

2. Placement of Stents With Self-Expandable Metal (SEMS):

• These are alternatives to endoscopic balloon dilation.

• Stents are made up of stainless steel or nitinol.

• The stent is inserted into the duct where the obstruction is present with the help of endoscopy to visualize the exact location.

If the gastric outlet obstruction is caused by malignancy or cancer, then the surgical treatment includes:

Laparotomy:

• An exploratory or diagnostic laparotomy is done to assess the severity and extent of the disease.

• It is an open surgery done to assess the internal structures.

Endoscopic Stent:

• It is done when there is no obstruction at the insertion site.

• A metal or plastic tube is inserted into the duct to allow the flow of fluids.

• These are hollow devices that prevent the collapse of the organ.

Decompressive Gastrostomy:

• Decompressive percutaneous gastrostomy tubes (PEG tubes) are inserted to decompress the symptoms of nausea and vomiting in the patient.

• These tubes help in draining out the gas or fluids from the stomach.

Lumen Apposing Metal Stent (LAMS):

• A stent is inserted into the stomach to the small bowel to create a bypass.

• This process is performed with the help of endoscopic ultrasound that guides the exact location for insertion.

Where Are Peg Tubes Placed in Abdomen With Gastric Outlet Obstruction?

The tubes are inserted into the jejunum, which is the second part of the small intestine or in the left upper quadrant of the stomach.

What Are the Complications of Gastric Outlet Obstruction?

• Perforation - Small holes or punctures created in the lining of the stomach or small intestine.

• Malnutrition is a major complication.

• Pain and bleeding from the obstruction site are seen during the surgical treatment.

Conclusion

Gastric outlet obstruction is a rarely occurring condition, mainly caused by peptic ulcer disease. Males are more likely to suffer from gastric outlet obstruction than females. The condition can have a benign or malignant cause and is best treated with a surgical approach such as endoscopic balloon dilation or stent placement. It is important to consider the nutritional status of the patient, which may deteriorate because of vomiting. Therefore, providing nutritional support before the surgery is important.