Stomach and duodenum Basic Science Review

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Stomach and duodenumBasic Science Review

• Donald Baril
• October 21, 2004

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Embryology

• Stomach and duodenum develop from the caudal
  portion of the embryonic foregut
• Development starts in the 5th week of gestation
• Rate of growth of the left gastric wall gtright
  gastric wall

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Anatomy

• Cardia immediately distal to the GE junction
• Fundus above the GE junction
• Body central portion marked distally by the
  angularis incisura
• Pylorus distal segment

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Anatomic relationships

• Anteriorly left hemidiaphragm, left lobe of the
  liver, anterior portion of the right lobe of the
  liver, parietal surface of the abdominal wall
• Posteriorly left diaphragm, left adrenal, neck,
  tail, body of the pancreas, aorta and celiac
  trunk
• Inferiorly transverse colon and its mesentery

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Blood supply
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Lymphatic drainage
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Nervous supply

• Vagal trunks
• Left anterior
• Hepatic branch
• Anterior gastric wall
• Right posterior
• Celiac division
• Posterior gastric wall

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Gastric mucosa

• Lined by simple columnar cells with 3 types of
  gastric glands
• Cardiac contain mucus glands, undifferentiated
  glands and endocrine glands
• Oxyntic contain acid-secreting parietal cells
  and chief cells that synthesize pepsinogen
• Antral contain gastrin-secreting cells

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Pepsinogen

• Synthesized by chief cells
• Activated by falling pH level
• Catalyzes hydrolysis of peptide bonds
• Initiates protein digestion
• Most important stimuli for secretion is
  stimulation of muscarinic receptors

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Intrinsic factor

• Secreted by the parietal cells
• Necessary for the absorption of vitamin B12 from
  the terminal ileum
• Secretion stimulated by histamine, acetylcholine,
  and gastrin
• Atrophy of the parietal cells, characteristic of
  pernicious anemia, results in deficiency of IF

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Acid secretion

• Basal acid secretion is 2-5 mEq/hr
• 3 phases
• Cephalic mediated by cholinergic stimulation
• Gastric stimulated by presence of partially
  hydrolyzed food and gastric distension
• Small peptide fragments and amino acids -gt
  gastrin release
• Intestinal mediated by secretin, somatostatin,
  peptide YY, and gastric inhibitory peptide

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Gastric peristalsis

• Basic electrical rhythm of 3 cycles/minute
• Increased contractile activity with the ingestion
  of food
• Pylorus opens and closes every 2-3/seconds,
  allowing for passage of a small amount of fluid
• Remaining fluid is propelled retrograde

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Peptic ulcer disease

• 300,000 new cases/year in the U.S.
• 4 million people receiving medical therapy
• Pathogenic factors
• Acid secretion increased basal secretion,
  increased meal response, abnormal gastric
  emptying
• Environmental NSAID use, H. pylori infection,
  cigarette use
• Mucosal defense decreased bicarbonate
  production, decreased gastric mucosal
  prostaglandin production

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Peptic ulcer disease - Pathogenesis

• Cigarette smoking alters mucosal blood flow,
  decreased mucosal PGE2 production and increases
  acid stimulation
• NSAIDs systemic suppression of PGE2 production

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Peptic ulcer disease H. pylori

• 1886 - ? Relationship between peptic ulcer
  disease and spiral bacteria
• 1981 - Robin Warren, M.D., an Australian
  pathologist, discovered numerous bacteria living
  in tissue taken during a stomach biopsy.
• Spiral urease-producing, Gram-negative bacteria
  always accompanied changes in the stomach lining

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Peptic ulcer disease H. pylori

• 1982 - Barry Marshall, M.D., joined Dr. Warren in
  his research
• 1984 - The Lancet, 100 people undergoing
  endoscopy, all 13 people with duodenal ulcers and
  24 of 28 people with gastric ulcers were infected
  with Helicobacter pylori

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Peptic ulcer disease H. pylori

• 1984 - Dr. Marshall swallowed a large number of
  the bacteria himself to test his ideas about H.
  pylori
• For 5 days, he noticed nothing. Then, he began to
  experience nausea and vomiting
• Symptoms resolved on their own after 14 days, an
  endoscopy on the 8th day revealed that he had
  developed severe gastritis

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Peptic ulcer disease H. pylori

• 1988 - Marshall and Warren published a report
  demonstrating the effectiveness of antibiotics in
  the treatment of peptic ulcers
• Randomly assigned 100 people with duodenal ulcers
  to receive either cimetidine or an antibiotic
  regimen that targeted H. pylori
• Ulcers returned in 90 of people treated with
  cimetidine
• Ulcers returned in only 21 of those whose H.
  pylori infection was eliminated with an
  antibiotic and bismuth

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PUD Gastric ulcer types

• Type I lesser curvature
• Antral gastritis and H. pylori infection often
  present
• Type II prepyloric
• Occur in association with duodenal ulcers
• Type III antrum
• Result from NSAID use
• Type IV lesser curvature, near the GE junction
• Similar pathophysiology to type I

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PUD Clinical features

• Patients present with epigastric pain
• Typically worse in the morning
• Burning, stabbing, gnawing
• Commonly relieved by eating or taking antacids
• Patients may present acutely with bleeding,
  perforation, or obstruction

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PUD - Diagnosis

• Barium contrast study or endoscopy

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PUD H. pylori and diagnosis

• Serology reliable marker of initial infection
• Remains even after the eradication of bacteria
• Urea breath test more reliable marker of active
  infection
• Labeled urea is converted into ammonia and
  labeled carbon dioxide by the H. pylori urease in
  the stomach
• Endoscopic biopsy

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PUD Medical Treatment
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Surgical treatment of PUD

• Indicated for failures of medical treatment and
  in patients presenting with complications
• Truncal vagotomy with drainage (pyloroplasty,
  antrectomy, or gastrojejunostomy)
• Proximal gastric vagotomy
• Highly selective vagotomy

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• TV and drainage
• 1-2 operative mortality
• TV/antrectomy
• 1-2 risk of recurrent ulceration
• 10-15 risk of persistent dumping sxs
• TV/pyloroplasty
• 10 risk of recurrent ulceration
• 1 risk of persistent dumping sxs

• HSV
• lt1 operative mortality
• 1 risk of persistent dumping sxs
• 10-15 risk of recurrent ulceration

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Physiological changes after truncal vagotomy

• Gastric effects
• Decreased basal acid output
• Decreased maximal acid output
• Increased fasting and postprandial gastrin
• Gastrin cell hyperplasia
• Accelerated liquid emptying
• Nongastric effects
• Decreased pancreatic exocrine secretion
• Decreased postprandial bile flow
• Diminished release of vagally mediated peptide
  hormones

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Gastric surgery complications - Dumping syndrome

• Delivery of hyperosmotic fluid to the small bowel
  leading to massive fluid shifts
• Sxs postprandial palpitations, sweating,
  weakness, dyspnea, nausea, cramps, diarrhea,
  syncope
• Dx hyperosmolar glucose load will elicit sxs
• Tx multiple small, low-fat, low-carbohydrate
  meals that are high in protein
• Preprandial octreotide may reduce sxs

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Gastric surgery complications - Alkaline reflux
gastritis

• Reflux of bile into stomach following BI, BII, or
  pyloroplasty
• Sxs Postprandial pain, bilious emesis
• Dx Endoscopy, HIDA scan
• Tx Cholestyramine, reglan, acid-suppression
• Surgical tx conversion to Rou-en-Y
  gastrojejunostomy

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Gastric surgery complications
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Perforated peptic ulcer

• Incidence of perforation is 5-10 of all patients
  with peptic ulcer disease
• Incidence of perforation has not decreased
  proportional to the overall decline in peptic
  ulcer disease over the past few decades
• Perforation is often the first clinical
  presentation of the disease

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Perforated peptic ulcer

• Mortality of 1-20
• Accounts for 70 of deaths associated with PUD
• Negative prognostic factors include presence of
  comorbid conditions, gt 24 hours since time of
  perforation to time of repair, presence of shock

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Perforated peptic ulcer - Presentation

• Sudden onset of severe upper abdominal pain
• May be referred to back or shoulder
• Boardlike rigidity
• Mild leukocytosis
• Mildly elevated serum amylase levels
• Dx based on upright CXR in 85 of cases
• Most commonly occurs on anterior gastric or
  duodenal wall

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Perforated peptic ulcer Treatment options

• Simple closure
• Simple closure with overlying omental patch
• Simple closure with fibrin glue sealing
• Closure with Graham patch
• Simple closure with overlying omental patch or
  Graham patch closure with
• truncal vagotomy
• proximal gastric vagotomy
• highly selective vagotomy

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Timing of acid reduction

• Patients are selected for an immediate
  acid-reducing procedure after perforation if
• Perforation less than 24 hours
• No comorbid conditions
• No evidence of shock
• History of sxs gt 3 months
• In these patients, ulcer recurrence is lt 10 with
  no additional perioperative morbidity or
  mortality

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Timing of acid reduction

• If the traditional criteria are met,
  acid-reduction surgery is strongly indicated in
  patients who
• have previously failed an H. pylori eradication
  regimen
• are known to be not infected by H. pylori
• have suffered other complications of PUD
  (including bleeding and/or obstruction)
• are NSAID dependent

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Gastric cancer

• Incidence in U.S. 10/100,000
• Incidence in Japan 78/100,000
• 10th most common cancer
• 5-year survival in U.S. is 12
• 5-year survival in Japan in 53
• Overall incidence in U.S. is decreasing

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Gastric cancer Risk factors

• Environmental/general dietary nitrites, smoking,
  H. pylori infection, black race, male gender, low
  socioeconomic class
• Gastric chronic atrophic gastritis,
  hypochlorhydric or achlorhydric state, pernicious
  anemia, adenomatous polyp, previous gastric
  surgery

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Pathology of gastric cancer

• 95 of gastric cancers are adenocarcinomas
• Remaining 5 includes lymphoma, carcinoid, GISTs,
  and squamous cell
• Macroscopically divided into ulcerative (75),
  polypoid (10), scirrhous (10), and superficial
  (5)
• Histologically divided into intestinal and
  diffuse
• Over past few decades, increase in proximally
  occurring tumors

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Presentation of gastric cancer

• Vague epigastric discomfort
• Anorexia
• Weight loss
• Vomiting
• Dysphagia
• Palpable mass in up to 30 of patients
• 10 present with evidence of metastatic disease
  (Virchows node, Sister Mary Josephs node,
  Blumers shelf, ascites, jaundice)

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Surgical treatment of gastric cancer

• Total gastrectomy with Roux-en-Y reconstruction
• Advocated for proximal and midbody tumors
• Subtotal gastrectomy
• Advocated for distal tumors
• Entails resection of ¾ of the stomach
• 5-6 cm resection margin when possible
• ? Splenectomy
• Routine splenectomy does not improve survival but
  does increase morbidity and mortality

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Lymphadenectomy in gastric cancer

• Role of extended lymphadenectomy in gastric
  cancer remains controversial
• Current recommendation is D1 dissection
• D1 removal of all nodal tissue within 3 cm of
  the primary tumor
• D2 D1 clearance of hepatic, splenic, celiac,
  and left gastric lymph nodes
• D3 D2 omentectomy, splenectomy, distal
  pancreatectomy, and clearance of porta hepatis
  lymph nodes

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Gastric lymphoma

• Increasing in incidence
• Accounts for 2/3 of GI lymphoma
• Average age at presentation is 60
• Endoscopy permits diagnosis in 90 of patients
• Most lesions are located in the distal stomach,
  spread locally by submucosal infiltration
• Initial treatment is chemotherapy doxorubicin
  and cyclophosphamide
• Surgery reserved for patients with an incomplete
  response or a recurrence

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Gastroduodenal Crohns

• Prevalence of 0.5-13 in patients with
  ileocolonic disease
• UGI involvement is typically in the antrum and
  duodenal bulb
• Sxs include epigastric pain and dyspepsia
• Hematemesis and melena are rare

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Gastroduodenal Crohns

• Duodenal fistula are rare (0.5)
• Fistulae involving the stomach almost always
  originate from the colon or small bowel
• Corticosteroids are the mainstay of medical tx
• Unknown role of acid reduction therapy

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Surgery for gastroduodenal Crohns

• Gastrojejunostomy
• Most commonly performed surgery for
  gastroduodenal Crohns
• Indicated for obstruction and fistulization
• Unknown role for vagotomy
• Stricturoplasty
• ?Advantageous compared to gastrojejunostomy given
  less mobilization of small bowel

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Which of the following statements is/are true
regarding the arterial supply to the stomach

• A) The right gastric artery, a branch of the SMA
  supplies the gastric antrum
• B) Gastric viability may be preserved after
  ligation of all but one major artery
• C) In cases of celiac artery occlusion, gastric
  viability is maintained collaterally through
  pancreaticoduodenal arcades
• D) The left gastroepiploic artery is a branch of
  the celiac trunk

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At a cellular level, the major stimulant(s) of
acid secretion by the gastric parietal cell
is/are

• A) Histamine
• B) Prostaglandin E2
• C) Acetylcholine
• D) Gastrin
• E) Norepinephrine

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Which of the following statements is/are correct
regarding intrinsic factor

• A) Intrinsic factor is produced in chief cells
  located in the gastric fundus
• B) Total gastrectomy is following by folate
  deficiency caused by vitamin malabsorption due to
  intrinsic factor deficiency
• C) Secretion of intrinsic factor, like that of
  acid, is stimulated by gastrin, histamine, and
  acetylcholine
• D) Intrinsic factor deficiency accompanies antral
  gastritis caused by H. pylori infection

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Gastrin release is increased by which of the
following

• A) Antral acidification
• B) Ischemia
• C) Histamine
• D) Antral distension
• E) Trauma

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Appropriate treatment for a perforated ulcer in a
35-year old male who has been treated for peptic
ulcer disease for the past 7 years and is
hemodynamically stable is

• A) Nasogastric suction and antibiotics
• B) Closure of the perforation
• C) Parietal cell vagotomy and pyloroplasty
• D) Truncal vagotomy and gastroenterostomy

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Which of the following statements is/are correct
with regard to pyloric obstruction secondary to
peptic ulceration

• A) Pyloric obstruction is suggested by
  hypochloremic hyponatremic alkalosis
• B) Pyloric obstruction is suggested by
  hypochloremic hypokalemic alkalosis
• C) Approximately 80 of patients with benign
  gastric outlet obstruction obtain permanent
  relief with endoscopic balloon dilatation
• D) The lifetime risk of pyloric obstruction among
  patients with peptic ulcer is 40

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50 yo M underwent truncal vagotomy with BII
reconstruction 2 yrs ago. He now has postprandial
pain, nausea, bilious emesis. Endoscopy reveals
bile in the stomach evidence of severe gastritis.
Appropriate therapy would include

• A) Octreotide administration
• B) Conversion of BII gastrojejunostomy to BI
  gastroduondenostomy
• C) Conversion of BII gastrojejunostomy to
  Roux-en-Y gastrojejnostomy
• D) Roux-en-Y hepaticojejunostomy

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Which of the following conditions is considered
to increase the risk of gastric cancer

• A) Pernicious anemia
• B) Previous partial gastrectomy
• C) Gastric hyperplastic polyps
• D) Gastric adenomatous polyps

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With regard to operative management of gastric
carcinoma, which of the following is/are correct

• A) Resection margins of 2 cm are necessary to
  prevent recurrence due to intramural metastasis
• B) Prophylactic splenectomy has been shown to
  improve outcome among similarly staged patients
• C) Extended lymphadenectomy that includes nodes
  along the aorta and esophagus has not been shown
  to improve survival in North American trials
• D) Long-term survival is rare if adjacent organs
  must be resected to achieve local control

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Which of the following statements regarding
gastric lymphoma is/are correct

• A) More than one-half of GI lymphomas occur in
  the stomach
• B) The peak incidence of gastric lymphoma is in
  the 2nd and 3rd decades of life
• C) Endoscopic biopsy provides enough information
  for a diagnosis in 90 of cases
• D) Gastric perforation occurs among 40 of
  patients treated with cytolytic agents instead of
  gastrectomy