Ulcers occur in the pylorus or duodenal bulb and are prone to cause pyloric obstruction. There are two types, temporary and permanent, which may coexist. Approximately 10% of ulcer patients develop pyloric obstruction. In the initial stage of obstruction, the discharge of gastric contents becomes difficult, leading to reflexive enhancement of gastric peristalsis. By the advanced stage, compensatory function becomes insufficient, muscles atrophy, peristalsis becomes extremely weak, and the stomach enters a state of dilation.

bubble_chart Pathogenesis

There are four types of ulcer disease complicated by pyloric obstruction:

1. Spastic obstruction: Caused by reflex spasm of the pyloric sphincter due to irritation from ulcers near the pylorus.
2. Inflammatory edematous obstruction: Resulting from inflammation and edema of ulcers in the pyloric region.
3. Cicatricial obstruction: Caused by callus induration and scar contracture after ulcer healing.
4. Adhesive obstruction: Due to adhesions or traction following ulcer inflammation or perforation.

In the initial stage of obstruction, gastric peristalsis strengthens to overcome the obstruction, leading to relative hypertrophy of the gastric wall muscles and grade I gastric dilation. In the advanced stage, compensatory function declines, gastric peristalsis weakens, and the gastric wall relaxes, resulting in significant gastric dilation. Prolonged retention of large amounts of gastric contents irritates the mucous membrane, causing chronic inflammation, which further exacerbates the obstruction, creating a vicious cycle. Due to prolonged inability to eat and frequent vomiting, water-electrolyte imbalance and severe malnutrition occur. Large amounts of hydrogen and chloride ions are lost with gastric fluid, reducing chloride ions in the blood and increasing bicarbonate ions, leading to metabolic alkalosis. Potassium is lost not only through vomiting but also excreted in large amounts in urine, potentially causing hypokalemia. Therefore, hypokalemic hypochloremic alkalosis is relatively common in patients with pyloric obstruction.

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1. vomiting: Vomiting is a prominent symptom of pyloric obstruction, characterized by: vomiting often occurring in the afternoon or evening, large amounts of vomitus (up to more than one liter at a time), the vomitus consisting of stagnant food with a sour odor and no bile. After vomiting, the abdomen feels more comfortable, so patients often induce vomiting themselves to relieve symptoms.
2. Gastric peristaltic waves: The abdomen may show a distended gastric outline, and sometimes gastric peristaltic waves can be observed. These waves start below the left costal arch, move toward the right abdomen, and may even peristalt in the opposite direction.
3. Succussion splash: Due to the large amount of distended contents, a splashing sound can be heard when tapping the upper abdomen.
4. Others: Oliguria, constipation, dehydration, and weight loss; in severe cases, cachexia may occur. After oral administration of barium, the barium has difficulty passing through the pylorus. Gastric dilation, weak peristalsis, and a large amount of fasting retention fluid are observed, with barium sinking to create a phenomenon of gas, liquid, and barium layers.

bubble_chart Diagnosis

Patients with a long history of ulcers and typical symptoms of gastric retention and vomiting can be diagnosed without difficulty, with X-rays or gastroscopy performed when necessary.

bubble_chart Treatment Measures

1. Non-surgical therapy: For obstruction caused by pylorospasm or inflammatory edema, non-surgical treatment should be adopted. The methods include gastrointestinal decompression, maintaining water and electrolyte balance, and systemic supportive therapy.
2. Surgical therapy: Pyloric obstruction caused by scarring and cases where non-surgical treatment is ineffective should be considered as surgical indications. The purpose of the surgery is to relieve the obstruction, allowing food and gastric juice to enter the small intestine, thereby improving the patient's overall condition. Common surgical methods include:
   1. Gastrojejunostomy: This method is simple, has good short-term effects, and a low mortality rate. However, due to the high incidence of postoperative anastomotic ulcers, it is rarely used nowadays. It may still be considered for elderly and frail patients with low gastric acid and extremely poor overall condition.
   2. Subtotal gastrectomy: For patients in generally good condition, this is the most commonly used surgical method in China.
   3. Vagotomy: Vagotomy combined with antrectomy or vagotomy with gastric drainage is more suitable for young patients.
   4. Highly selective vagotomy: There have been reports of highly selective vagotomy combined with pyloric dilation achieving satisfactory results in recent years.
   Patients with pyloric obstruction require thorough preoperative preparation. Gastrointestinal decompression should be performed 2–3 days before surgery, with daily gastric lavage using warm saline to reduce gastric tissue edema. Blood transfusion, fluid infusion, and nutritional improvement are necessary to correct typical edema and electrolyte imbalances.

bubble_chart Differentiation

1. Active phase ulcer-induced pyloric spasm and edema: presents with ulcer pain symptoms, obstruction is intermittent, vomiting is severe but without gastric dilation, and vomitus does not contain retained food. Medical treatment can alleviate or relieve obstruction and pain symptoms.
2. Pyloric obstruction caused by stomach cancer has a shorter course, milder gastric dilation, and rare gastric peristaltic waves. In the advanced stage, a mass may be palpable in the upper abdomen. X-ray barium meal examination may reveal filling defects in the gastric antrum, and biopsy via gastroscopy can confirm the diagnosis.
3. Obstruction below the duodenal bulb due to sexually transmitted disease changes: such as duodenal tumors, annular pancreas, or duodenal stasis can cause duodenal obstruction, accompanied by vomiting, gastric dilation, and retention, but the vomitus often contains bile. X-ray barium meal or endoscopic examination can determine the nature and location of the obstruction.