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.
Intrinsic factor is secreted by
parietal cells
necessary for the absorption of vitamin B12 in the terminal ileum.
Pepsinogen is secreted by
chief cells
in response to gastrin and vagal stimulation.
Pepsinogen is a zymogen which, when in an acidic environment, cleaves itself to form pepsin, a hormone responsible for the digestion of proteins.
Gastrin is released by
G cells in the antrum of the stomach.
It stimulates the secretion of gastric acid (HCl) by the parietal cells of the stomach.
CCK, which is released in response to and has what effect on the stomach
lipids in the duodenum,
CCK released from duodenal mucosa inhibits the motility of the proximal stomach through a vagovagal reflex pathway but stimulates pyloric contractile activity by an endocrine mechanism of action.
clinical features that mandate endoscopic hemostatic therapy
Hematemesis,
age older than 60 years,
serious medical comorbidity
RE-bleeding during hospitalization
endoscopic findings of:
visible vessel,
oozing,
bleeding associated with an adherent clot
When is Operative intervention is appropriate for upper GI bleed
massive hemorrhage leading to shock or cardiovascular instability,
prolonged blood loss necessitating continuation of transfusion,
recurrent bleeding during medical therapy or after endoscopic therapy,
recurrent hemorrhage necessitating hospitalization (this is different from rebleed during hospitalization
Operative therapy for upper GI bleed should consist of
duodenotomy
direct ligation of the bleeding vessel within the ulcer base
followed by antibiotic therapy against Helicobacter pylori to permanently reduce acid production
Whether a perforated peptic ulcer requires simple closure or definitive treatment hinges on all of the following
most series have shown no significant difference in morbidity or mortality for simple closure compared with a definitive ulcer operation,
unstable patients may not tolerate the longer operative times required for a definitive operation.
Patients undergoing definitive operation have a lower chance of ulcer recurrence.
The presence of a posterior (“kissing”) ulcer should lead to serious consideration of a definitive ulcer operation, to avoid the possibility of bleeding from this ulcer in the early postoperative period.
a history of chronic peptic ulcer disease
Kissing ulcers
ulcers opposite from each other on the anterior and posterior walls.
which are more common duodenal or gastric ulcers
duodenal 2-3 times more frequent than gastric ulcers
increase gastric bicarbonate secretion.
Cholinergic agonists,
vagal stimulation,
sham feeding
Prostaglandin E2 and its synthetic derivatives are potent stimulants of bicarbonate secretion.
Indomethacin and other drugs that inhibit prostaglandin formation decrease mucosal bicarbonate secretion.
effects of vagotomy of serum gastrin levels
INCREASE
Gastric ulcers in the stomach most often are found where
on the lesser curvature near the incisura angularis.
In addition, 97% of all gastric ulcers occur within 2 cm of the junctional zone between fundic and antral mucosa.
Approximately 60% of ulcers are located at or slightly above the angularis.
Fifteen to 23% of gastric ulcers are within the gastric antrum, and 10% are high on the lesser curvature.
Only 5% of gastric ulcers are found on the greater curvature.
Jejunoileal bypass complications
CIRRHOSIS!!
Bacterial overgrowth in the bypassed intestinal segment coupled with protein malabsorption is postulated to be responsible for development of cirrhosis, the most serious complication of jejunoileal bypass. Bacterial overgrowth can be temporarily suppressed by metronidazole. Development of hepatic dysfunction is an indication for reversal of the bypass.
abondoned type of bariatric surgery
GALLSTONES! - Malabsorption of bile salts coupled with rapid weight loss
Multiple kidney stones are caused by excessive absorption of oxylate from the colon, where oxylate is ordinarily chelated with calcium.
Malabsorption results in severe diarrhea, electrolyte abnormalities, metabolic acidosis, and anemia.
The best elective operation for benign gastric ulcer is
distal gastrectomy with gastroduodenal anastomosis.
The ulcer should be included in the antrectomy specimen.
The addition of truncal vagotomy does not appear to diminish the recurrence rate.
Definitive management of hemorrhage is a procedure designed to control bleeding and to prevent recurrent ulceration. Antrectomy, which includes the ulcer with gastroduodenostomy, is considered the best procedure for surgical management of this complication. The quoted operative mortality rates in this setting range from 10% to 40%
[Gastrojejunostomy is an acceptable alternative. ]
The operative mortality rate associated with this procedure is 2% to 3%, the recurrence rate is 3%, and good to excellent clinical results can be anticipated for more than 90% of patients.
Diagnostic angiography is used to examine patients when
cannot undergo endoscopy
or
endoscopy has been unsuccessful in finding the source of hemorrhage.
depends on the presence of active ARTERIAL bleeding at the time of the study.
]rate greater than 0.5 to 1 mL/min.
correlates with the loss of 4 to 5 units of blood per day by humans.
Patients are likely to be bleeding at a rate angiographically detectable if they need continuous volume infusion to maintain hemodynamic stability.
Selective visceral angiography and endoscopy are complementary in the evaluation of active bleeding. In examinations of massively bleeding patients, endoscopic visualization often is severely limited, and selective mesenteric arteriography often shows the site of bleeding.
With selective catheterization and injection of the celiac axis and superior mesenteric artery, the site of hemorrhage is identified in 40% to 60% of patients.
the most clearly established gastric inhibitory influence is
suppression of gastrin release by exposure of the antral mucosa to luminal acid.
Secretion of intrinsic factor is stimulated by
stimulated by gastrin, histamine, and acetylcholine.
like acid
A 40-year-old man is admitted to the hospital after vomiting blood. Endoscopy shows a bulging mass on the posterior wall of the mid-stomach covered by normal mucosa with a small bleeding ulcer in the center. The most likely diagnosis is
GIST
diagnose a gastrinoma
T, a secretin stimulation test is performed. A baseline gastrin level is drawn, then 2 units per kilogram of secretin are administered intravenously as a bolus, and gastrin levels are drawn at 5 minute intervals for 30 minutes. An increase in gastrin of more than 200pg/ml above the basal level supports the diagnosis of a gastrinoma.
GIST tumors On endoscopy the tumors are typically seen as
large bulge with overlying mucosa (that is normal)
typically do not involve the mucosal layer.
can present with small ulcer and bleeding
the most common presenting symptoms for a GIST are
pain, bloating and early satiety.
sometimes present:
melena or anemia from ulceration of the mucosal layer
reported patients that present with tumor rupture and hemorrhage.
The symptoms produced by gastric cancer
Pain is present in 70% - usually is constant, nonradiating, and NOT improved by food ingestion.
One third of patients have guaiac-positive stool.
The 5-year survival rate for patients with stage I-IV gastric cancer
stage I (in situ carcinoma!) is close to that of the healthy population.
For patients with disease in stage II, the 5-year survival rate approximates 45%, whereas 15% of patients with stage III disease survive 5 years. The long-term survival rate with systemic metastasis is negligible.
most common etiology of gastric outlet obstruction in adult
Gastric adenocarcinoma
sporadic versus inherited gastrinomas
CAREFUL - sporadic is BETTER in this case
Significant portion (~50%) of patients with sporadic-type gastrinomas are cured by surgical resection.
Surgical cure of MEN I tumors is seldom achieved, 0-10%, due to the aggressive growth pattern and occurrence of multiple tumors spread throughout the “gastrinoma triangle”. Once the tumor is >4cm in size, approximately 25-40% will have liver metastasis. Sporadic forms account for 80% of gastrinomas, and are often found as solitary tumors within the wall of the duodenum.
Ulcers along the greater curvature tend to have what association and how are they managed
prompt earlier intervention given the association of disease in this location with malignancy.
most common gastric ulcer
type I disease is the most common and comprises approximately 60% of benign gastric ulcers.
percent of H pylori associated gastric versus duodenal ulcers
It is now believed that 90% of duodenal ulcers and approximately 75% of gastric ulcers are associated with H. pylori infection.
The most common symptoms associated with duodenal ulcer disease are
midepigastric abdominal pain that is usually well localized. The pain is generally tolerable and frequently relieved by food.
Surgical Treatment Recommendations for Complications Related to Peptic Duodenal Ulcer Disease
Intractable: Parietal cell vagotomy ± antrectomy
Bleeding: Oversewing of bleeding vessel with treatment of H. pylori
Perforation: Patch closure with treatment of H. pylori
Obstruction: Rule out malignancy and gastrojejunostomy with treatment of H. pylori
Gastric carcinoid tumors list 3 types and associations and relative features.
three types, on the basis of their association (or lack thereof) with hypergastrinemia.
Type I associated with chronic atrophic gastritis, are generally small (< 1 cm), and are often multiple and polypoid. They grow slowly and only rarely metastasize to regional nodes or distant sites.
Type II tumors associated with the Zollinger-Ellison syndrome and multiple endocrine neoplasia type I. They also grow slowly but are more likely to metastasize to regional lymph nodes and distant sites.
Type III (sporadic) gastric carcinoid tumors are the most biologically aggressive type. They are often large (> 1 cm) at the time of diagnosis and are not associated with hypergastrinemia. Type III lesions frequently metastasize to regional nodes (54%) or the liver (24%).
