Acute Gastritis

Pathological aspects of stomach-I Acute Gastritis. Pathological aspects of stomach-I OBJECTIVES By the end of the session the students should be able to: a. Discuss Acute Gastritis. b. Enlist the common causative agents in various age groups c. Explain the pathogenesis and pathology d. Enlist clinical features.

Normal Gastric mucosa Mucosa, Mucin &cytoprotection : The entire gastric mucosal surface is replaced every 2 to 6 days, Formation of an “unstirred” layer of fluid that protects the mucosa. PH of mucin layer is neutral as a result of HCO3+ secretion. Prevents large food particles from directly touching the epithelium. Mucosa & synthesis of prostaglandins, Prostaglandins enhance bicarbonate secretion. Prostaglandins inhibit acid secretion. Prostaglandins promote mucin synthesis. Prostaglandins increase vascular perfusion. Mucosa & acidity: The gastric lumen is strongly acidic with pH close to 1, > than a 1000,000 “million” times more acidic than the blood.

a. Discuss Acute Gastritis What is gastritis? Gastritis is an inflammation of the lining mucosa of the stomach. It is a common disease that may occur in two forms: [1] Acute form (Sudden or transient) [2] Chronic form (prolonged). Acute gastritis: is a transient mucosal acute inflammatory process that may be asymptomatic or cause variable degrees of clinical features: {1} Epigastric pain. {2} Nausea. {3} Vomiting. Erosive Gastritis morphologically, when acute gastritis presents with shallow erosions of the mucosa. Severe cases of acute gastritis- may be associated with: {1} Mucosal erosion. {2} Ulceration. {3} Hemorrhage with hematemesis and melena. {4} Rarely, massive blood loss.

The common causative agents in various age groups What are the most common causes of acute gastritis? 1. Heavy use of Aspirin (most common) and others NSAIDs. 2. Infection- H.pylori infection (Urease positive bacilli). 3. Sepsis (Streptococcal sepsis& Viral gastritis in immunosuppression) e.g. CMV and Candida in AIDS patients 4. Excessive Alcohol consumption. 5. Heavy Smoking. 6.Stress (major surgery, burns and trauma). 7.Shock-related mucosa ischemia (burns, brain trauma, surgery). 8. Ingestion of acids and alkali (accidently, suicidal ingestion). 9. Parasitic: Anisakis (worm associated with eating raw fish) . 10. Radiation (radiotherapy), and chemotherapy. 11. Bile reflux gastritis and uremia 12. Mechanical trauma (nasogastric tube)

Mechanisms of Gastric injury and Protection .

Pathogenesis of Acute Gastritis Erosions may develop because of: The direct effects of a potentially toxic substance (e.g., alcohol, harsh chemicals=acids or bases). Reduced mucin synthesis as in the elderly. Hypoperfusion of the gastric mucosa in shock (Mucosal cells more susceptible to the action of pepsin &HCL). Aspirin and NSAIDs inhibit the local synthesis of prostaglandins & weaken mucosal defense system. 5. Radiation therapy, and chemotherapy (suppression of growth, usually regenerate every 2 to 6 days). Decreased oxygen delivery .

Pathology of Acute Gastritis=Morphology Four morphologic pattern: 1. Mild acute gastritis- difficult to recognize. 2. Acute (Active) inflammation- edema, congestion with neutrophilic infiltrates. 3. Gastric erosions- erosions, exudate, fibrin, localized. 4. Acute erosive hemorrhagic gastritis- When wide area of erosions with hemorrhage, may progress to ulcer.

Ulcer vs. Erosion of GIT Ulcer = Necrosis (or breach) involving the entire thickness of the mucosa that extend through the muscularis mucosa into the submucosa or deeper Erosion= Necrosis (or breach) involving only the superficial mucosa.

Morphology Active inflammation (Acute Gastritis) 1. Gross: diffusely hyperemic gastric mucosa. 2. Microscopic: {A} The surface epithelium& glands: is intact with scattered neutrophils among the epithelial cells “intraepithelial” or within mucosal glands. {B}The lamina propria: moderate edema & vascular congestion.

Morphology of Acute erosive hemorrhagic gastritis Define as concurrent erosions and hemorrhage, Hyperemic mucosa Large areas of the gastric surface erosions, the involvement is typically superficial. Pronounced neutrophilic. Fibrin-containing purulent exudate in the lumen Ulcer: erosions may progress to ulcers.

Clinical features of Acute gastritis Most critically ill patients admitted to hospital ICU. Asymptomatic. Epigastric pain. Nausea. Vomiting. Bleeding from superficial gastric erosions or ulcers that may require transfusion (Gastric Mucosal damage). Hemtamesis and melena. Rarely, massive blood loss. 6. Others Complications of Gastric ulcer: Bleeding. Perforation. Obstruction.

ACUTE GASTRIC ULCERATION The etiological factors of acute gastric ulceration are:: Well-known complication of therapy with NSAIDs. Severe physiologic stress. Types of acute gastric ulceration: given specific names, based on location and clinical associations: Stress ulcers: shock, sepsis, or severe trauma. (Stomach). Cushing ulcers- occurs Gastric, duodenal, and esophageal ulcers arising in persons with CNS injury with intracranial disease, carry a high incidence of perforation. NB: Curling ulcers: (Proximal duodenum), a\w Burn or trauma.

Acute gastric ulceration-Pathogenesis is complex & not well-understood. NSAID-induced ulcers are related to cyclooxygenase inhibition This prevents synthesis of prostaglandins. Lack of prostaglandins synthesis lead to: Deceased bicarbonate secretion. Reduced mucin synthesis. Reduced mucosal vascular perfusion. Lesions associated with intracranial injury- caused by direct stimulation of vagal nuclei, which lead to: Hypersecretion of gastric acid. Systemic acidosis evoke gastric acid secretion& damage to the cells. Hypoxia and reduced blood flow caused by stress-induced splanchnic vasoconstriction.

Acute gastric ulceration-Morphology Macroscopic: Site: anywhere in the stomach Shape: irregular, rounded. Size: < than 1 cm diameter. Number: Singly, often multiple Margins: not indurated. Base: stained brown to black by acid digestion of extra- vasated blood.

Acute gastric ulceration-Morphology Microscopic: Sharply demarcated& shallow. Transmural inflammation + Serositis. Suffusion of blood into the mucosa and submucosa. Absent scarring& thickening of blood vessels “chronic peptic ulcers” ** Healing with re-epithelialization, will take place within days to several weeks.

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