STOMACH Flashcards
mechanisms of Helicobacter pylori and its relation to duodenal ulceration.
H pylori infection of the antrum selectively blocks the inhibitory reflex pathways from the antrum to the gastrin-producing cells and the parietal cells of the proximal stomach.
results in local and regional effects, including hypergastrinemia and increased and prolonged acid secretion, thereby resulting in duodenal ulceration.
Although gastric and duodenal ulcer disease is currently believed to reflect H pylori infection in most cases, those infected with H pylori usually do not have peptic ulcers
Helicobacter pylori test
Many tests are available to the practicing clinician for the diagnosis of H pylori, including endoscopic biopsy, CLO tests, breath tests, and serum antibodies, but none is really a gold standard, particularly in young patients.
Urease testing yields false-negative results in about 10% of cases, and urease testing is much less expensive than histologic confirmation.
Eradication of H pylori in infected ulcer patients
bismuth PPI
metronidazole, tetracycline, clarithromycin, or amoxicillin
cure 90% of patients with one week of treatment.
Other regimens may require an additional week of treatment for cure.
Once cure is achieved, reinfection rates (in developed countries) are less than 0.5% / yr
Horizontal gastroplasty
stapling device to create a partition between upper and lower gastric pouches.
The failure rate (loss of <40% of excess weight) for horizontal gastroplasty ranges from 40% to 70%.
Vertical banded gastroplasty
stapled opening is made in the stomach with the stapling device 5 cm from the cardioesophageal junction.
Two applications of a 90-mm stapling device are made between this opening and the angle of His.
A 1.5- by 5-cm strip of polypropylene mesh is wrapped around the stoma on the lesser curvature and sutured to itself.
The vertical direction is preferred because there is less risk of gastric pouch devascularization or splenic injury.
With three superimposed applications of a 90-mm stapler, the incidence of staple line disruption has been less than 2%.
Roux-en-Y gastric bypass results in markedly better weight loss than does vertical banded gastroplasty. Although gastric bypass is unsuccessful for 10% to 15% of patients, weight loss seems to remain stable for most patients 5 years or more after surgery.
gastric Clinical features that prompt early endoscopic evaluation include
considerable weight loss,
symptoms of gastric outlet obstruction,
palpable abdominal mass,
positive stool Hemoccult result or blood loss anemia.
.
gastric Endoscopic features that suggest the presence of a malignant tumor
exophytic mass,
abnormal or disrupted mucosal folds,
necrotic ulcer crater,
bleeding from the edge of the ulcer crater,
stepwise depression of the ulcer edge,
heaped-up margins,
small extensions of the ulcer that blur a portion of the ulcer wall.
If initial gastric biopsies do not show malignant cells but the endoscopic appearance strongly suggests that carcinoma underlies the ulcer, what is mangement
another endoscopic examination with deeper biopsies should be undertaken
Dieulafoy lesion
vascular malformation
unusual cause of recurrent hematemesis
unusually large (1 to 3 mm in diameter) artery running through the gastric submucosa for variable distances.
Erosion of the gastric mucosa overlying the vessel results in necrosis of the arterial wall and brisk hemorrhage.
The mucosal defect usually is small, 2 to 5 mm, and without evidence of chronic inflammation.
diagnosis is most frequently made at endoscopy with the detection of an arterial bleed from a pinpoint mucosal defect.
In some instances, a small arterial vessel can be seen protruding from the gastric mucosa.
usually within 6 cm of the esophagogastric junction along the LESSER curvature.
Management
WEDGE resection excision of the proximal lesser curvature.
what percent of GI lyphomas present in the stomach
50% stomach - most common organ involved in extranodal lymphoma.
peak incidence 60-70s
Radiologic findings of gastric lymphoma
similar to adenocarcinoma.
Endoscopic examination has become the diagnostic method of choice!
ombined with endoscopic brush cytologic examination provides a diagnosis in approximately 90% of cases.
if When gastric lymphoma is first diagnosed by endoscopic what is next step
[evidence of systemic disease should be sought]
Computed tomography of the chest and abdomen to detect nodes
lymphangiography,
bone marrow biopsy,
biopsy of enlarged peripheral lymph nodes may be appropriate.
manage primary gastric lymphomas
Gastrectomy is the first step in the therapeutic strategy.
Increasing numbers of patients are treated with chemoradiation therapy alone.
The risk of perforation if primary gastric lymphoma is managed with cytolytic agents and not resected approximates 5%.
The risk fators of gastric cancer
Adenomatous polyps. The risk of cancer has been estimated at 10% to 20% and is greatest for polyps more than 2 cm in diameter.
NOT Hyperplastic polyps
Other risks:
chronic gastritis associated with pernicious anemia.
carcinoids also exists among patients with pernicious anemia, presumably because of the effects of long-standing hypergastrinemia.
previously undergone partial gastric resection.
Postgastrectomy cancer is a long-term concern; increased incidence of malignancy is not observed until 15 years postoperatively.
A 32-year-old otherwise healthy man has massive upper gastrointestinal bleeding. Upper endoscopic examination reveals a posterior duodenal ulcer with a visible, nonbleeding vessel. The patient responds to initial volume resuscitation and shows no evidence of active bleeding after 12 hours. Optimal care of this patient should include:
Proton pump inhibitors and management of H. pylori infection both have been shown to decrease the recurrence rate of hemorrhage. Antacids and H2 blockers have largely been supplanted by the more efficacious proton pump inhibitors.
Operation can be considered at this point in some cases because of the substantial risk of rebleeding associated with this lesion. This consideration is especially true in the care of older, debilitated patients.
In this young, otherwise healthy person, most surgeons would not recommend operation at this point. If bleeding reoccurs, the decision to operate or to perform a second endoscopic examination must be individualized. Either alternative would be appropriate in most cases.
Endoscopic signs of active gastric bleeding include
spurting or oozing of blood from under a clot
vissible vessel
Several risk factors or predisposing clinical conditions have been identified for stress ulceration
acute respiratory distress syndrome, severe burn of more than 35% oliguric renal failure, large transfusion requirements, hepatic dysfunction, hypotension, prolonged surgical procedures, sepsis from any source. multiple trauma
A direct correlation has been shown between acute upper gastrointestinal hemorrhage and the severity of critical illness.
Formation of duodenal ulcer depends on
duodenal ulcer have greater capacity for gastric acid secretion than do healthy persons.
increased basal acid secretion,
increased acid response to meal ingestion,
increased responsiveness to histamine stimulation.
Increased secretion of gastrin is a consequence of antral infection with Helicobacter pylori.
Maximal acid output in response to histamine averages 40 mEq/h in patients with duodenal ulcer, twice the output of healthy persons.
the surface epithelial cells of the stomach secrete
mucus
and
bicarbonate
secretion of bicarbonate helps to maintain a neutral pH of 7.0 in the gastric surface cell microenvironment, and the mucus secretion creates a viscous gel layer that serves as a protective cover.
Hydrochloric acid is secreted by
parietal cells
in response to stimulation by
gastrin,
acetylcholine,
histamine.
HCl secretion is inhibited by
prostaglandin.
