Basic Science: Stomach by 3LIxE4Wt

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									Basic Science: Stomach

     Grace Kim, MD
      May 23, 2007
Essential Anatomy
Beware: Aberrant L hepatic artery
• Parietal cell – BODY
  – Acid
  – Intrinsic Factor
• Mucus – BODY/ANTRUM
  – Mucus
• Chief – BODY
  – Pepsin
• G – ANTRUM
  – Gastrin
• D – BODY/ANTRUM
  – Somatostatin
• Surface epithelial – DIFFUSE
  – Mucus
  – Bicarb
  – ?Prostaglandin
                GI Hormones
• Gastrin – Antral G cells  increase acid
• Cholecystokinin - duo  GB contraction, pancreatic
  secretion
• Secretin – duo S cells  bicarb release, pancreatic
  secretion
• Glucagon – panc α cells  increase gluc release
• VIP – gut  SM relaxation, increase gut secretion
• Gastric inhibitory peptide = glucose insulinotropic
  peptide – K cells of gut  induce insulin secretion
• Somatostatin – gut  global gut inhibition
• Motilin – Mo cell of SB  upregulate MMC
• Peptide YY – gut  global inhibition
• Neurotensin – SB  bicarb release, decrease gastric
  motility
Benign Diseases of the
      Stomach
• Case: 80 yo woman with HTN and CAD is
  admitted with SBO. NGT decompression
  is initiated.

  – Is GI prophylaxis necessary? If yes, what
    kind?
  – What are we prophylaxing against?
            Stress Gastritis
• Develops within 48 hrs of stress
• Clinically-significant bleeding uncommon
  – 4% with risk factor, 0.1% without
Cook DJ, et al: Risk factors for gastrointestinal bleeding in critically ill patients.
Canadian Critical Care Trials Group. N Engl J Med 330:377-381, 1994
             Stress Gastritis
• Prophylaxis for critically-ill:
  – Mechanical vent > 48hrs
  – Coagulopathy
  – Spinal cord injury
  – Prior history of therapy
  – History of GI bleed
• +/- indications in the critically-ill
   – MODS
   – Cirrhosis
   – CNS injury
   – Steroids
   – Pressors
   – Multiple organ injuries
• General medical population
   – Data is sparse!
Treatment of Bleeding Stress Gastritis
 – Endoscopy
    • Coagulation
    • Injection
 – Interventional
    • Embolization
    • Selective vasopressin infusion
 – Surgical
    • Oversewing
    • Wedge resection
    • Total devascularization and vagotomy
        – Mucosal ischemia common, perforation uncommon
    • Total gastrectomy last resort
        Peptic Ulcer Disease
• Treated medically in most cases
• Elective surgery rare
• Emergency surgery still common
  – 130,000 cases/year
  – 9000 patient deaths/year
• GASTRIC ULCER            • DUODENAL ULCER
• 4 types, varying         • Usually associated
  etiologies                 with excess acid
• 75% HP                     production
• NSAID history more       • 90% HP
  common
• Usually older patients
         Type 3
Type 1




         Type 4
Type 2
                H. pylori
• Gram negative rod
• Produces urease (splits urea into
  ammonium and bicarb)
• Injury
  – Local toxins
  – Tissue immune response
  – Gastrin production
• 98% success in preventing recurrence if
  organism eradicated (vs. 75% without)
            Tests for H. pylori
•   Serology (90% sens/spec, + for > 1 yr)
•   Urea breath test (95% sens/spec)
•   Rapid urease test (90% sens/98% spec)
•   Histology (95% sens/98% spec)
•   Culture (to determine sensitivity to Abx)
             Pathogenesis
• Imbalance between acid secretion and
  mucosal defense

• “No acid, no ulcer”
• “No acid, no Factor X, no ulcer”
• Factor X = H. pylori, cigarette smoking,
  NSAIDs, steroids
• Case: 50 yo man, a smoker, with lower
  back pain on NSAIDs has an outpatient
  EGD for chronic melena. EGD
  demonstrates a 1 cm non-bleeding gastric
  ulcer in the body.
     -Management?
          Medical Treatment
• Stop NSAIDs
• Stop smoking
• Treat H. pylori
  – Triple therapy (OAC, OMC, OAM) x 1 week,
    PPI x 2 weeks
  – Success 90-95%
• PPI (96% ulcer healing at 8 weeks)
• Gastric ulcers: need rescope 8-12 weeks
• Case: 77 yo woman in the MICU is found
  to have a 5 cm gastric ulcer located along
  the lesser curvature. Multiple biopsies are
  taken which come back as chronic
  inflammatory tissue. She is on a PPI.
  – Management?
  Gastric ulcer: elective surgery
• Intractable ulcer
   –   Persist despite adequate treatment (3 mos)
   –   Recurs within 1 yr despite maintenance therapy
   –   Cycle of recurrence/remissions
   –   Cannot rule out malignancy
   –   ZE has been ruled out
• Giant gastric ulcer (> 3cm)

• OPERATION = Resection with reconstruction +/-
  vagotomy
   – Vagotomy for Type 2/3
Billroth reconstructions
Roux-en-Y reconstruction
Duodenal ulcer: elective surgery
• Intractable ulcer
  – Very rare



• Antrectomy or distal gastrectomy with
  truncal vagotomy
               Vagotomies
• Truncal vagotomy
• Selective vagotomy
  (not done any more)
• Highly selective =
  parietal cell =
  proximal gastric
  vagotomy
PUD: Emergent Surgical Indications

• Hemorrhage  oversew/excise/resect
  – Don’t forget to biopsy gastric ulcers
• Perforation  patch/excise/resect
  – Don’t forget to biopsy gastric ulcers
• Obstruction  resect

• Consider vagotomy if stable and HP(-),
  with recalcitrant disease, or NSAID-
  dependent
• Case: 30 yo otherwise healthy woman on
  no medications presents with peritonitis.
  On laparoscopy, you find a perforated
  duodenal ulcer.

• Management?
• Graham patch
• If known H. pylori negative – consider
  vagotomy and pyloroplasty
• PPI, HP treatment if positive
• Case: 65 yo man on NSAIDs for chronic
  lower back pain, smoker presents with
  hematemesis. On endoscopy, he has a
  gastric ulcer along the lesser curvature
  with a visible bleeding vessel. Heater
  probe is unsuccessful.

• Management?
•   OR
•   Gastrotomy – biopsy ulcer, oversew ulcer
•   Stop NSAIDs
•   Start PPI
•   Stop smoking
•   Test for H. pylori, treat if (+)
•   No vagotomy necessary
•   Rescope 8-12 weeks to document healing
• Case: 80 yo woman in MICU with bleeding
  duodenal ulcer, Hct 23 after 4U PRBCs.

• Management?
•   OR
•   Open pylorus
•   3-point vessel ligation
•   Pyloroplasty
•   Vagotomy if stable
•   PPI, test for H. pylori
• Case: 60 yo woman with long-standing
  history of PUD on multiple courses of PPI
  presents with chronic gastric outlet
  obstruction. H. pylori negative.
  Endoscopy demonstrates a pan-gastritis
  and a bulky antral ulcer. The scope
  cannot be passed into the duodenum.

• Management?
•   Hydrate, correct electrolytes
•   NGT decompression
•   Hyperalimentation or jejunal feeds
•   PPI
•   Antrectomy with BI with TV
• Case: The duodenum is stuck down and
  cannot be mobilized up for a BI. You
  proceed with a BII, however, it appears
  that your duodenal staple line is dehiscing.

• Management?
     Difficult Duodenal Stump
• Extra caution that the afferent loop is
  totally patent
• Buttress staple line with omentum
• Decompress afferent loop with Levin tube
• Lateral tube duodenostomy or retrograde
  jejunostomy
• Drain widely
• Leak mortality: 30 – 50%
Post-gastrectomy Issues
• Case: Your 70 yo woman who underwent
  a subtotal gastrectomy with Roux-en-Y for
  ulcer disease is recovering well. What
  supplements should she be placed on?
      Metabolic Disturbances
• Anemia
  – Iron-deficiency
  – B12-deficiency
• Impaired fat absorption
  – Fat-soluable vitamins (esp. Vit D)
• Impaired calcium absorption
• Case: You perform a truncal vagotomy
  and antrectomy with BII reconstruction for
  a 65 yo man with intractable ulcer disease.
  He begins to have severe pain in the RUQ
  on POD#5. CT demonstrates a large
  RUQ collection.
 Early Post-gastrectomy problems
• Leak at GJ, JJ (Roux-en-Y), or duodenal
  stump
  – Pain, fever, leukocytosis, biliary output from
    drains  reoperate
• Anastomotic bleed  EGD
• Obstruction  trial of conservative
  management, re-operate
• Delayed gastric emptying  conservative
  mangement and promotility agents
• Case: 80 yo man undergoes subtotal
  gastrectomy with Roux-en-Y for gastric
  cancer. He presents to your office with
  severe cramping, diaphoresis, and
  diarrhea after he eats.

• Diagnosis?
• Management?
 Late Post-gastrectomy problems
• Dumping
  – Early: Diaphoresis, weakness, tachycardia 15
    minutes after a meal
  – Late: Hypoglycemia 2 hours after meal

  – Etiology: Loss/bypass of pyloric sphincter,
    hormonal aberrations (VIP, cholecystokinin,
    neurotensin, peptide YY)
         Dumping Syndrome
• Medical management
  – Avoid sugars, carbs
  – Small, frequent meals with high protein, fat
  – Fiber
  – No liquids while eating
  – Octreotide
• Surgery = the last resort 1%
  – Isoperistaltic loop
  – Long-limb Roux-en-Y
  Late Post-gastrectomy problems
• Diarrhea
  – Medical management
  – Isoperistaltic loop as last resort
• Recurrent peptic ulcer
  – DDx: incomplete vagotomy, retained antrum,
    ZE, gastric stasis, NSAIDs, H. pylori infection,
    gastric cancer
      Recurrent Peptic Ulcer
• EGD: biopsy to r/o cancer, H. pylori
• Gastrin level and basal acid output: to
  evaluate for ZE and retained antrum
• Secretin stimulation test: ZE vs. retained
  antrum
• Check path report: incomplete vagotomy?
      Recurrent Peptic Ulcer
• Manage conservatively
• Operate for bleeding, perforation,
  obstruction, and “intractability”
• Operation: Step up from what was
  originally done
  – PCV  V and P
  – V and P  V and A
  – Subtotal gastrectomy  total gastrectomy
  – Consider thoracosopic truncal vagotomy
 Late Post-gastrectomy problems
• Gastroparesis
  – Loss of antral pump with vagotomy
  – Rule out mechanical obstruction
  – Treatment: Dietary modification, promotility
    agents
  – Surgery as last resort: Near total with Roux-
    en-Y
  Late Post-gastrectomy problems
• Bile reflux Gastritis
  – Workup: HIDA, EGD
  – No good medical treatment
  – Convert BII to long-limb RY (40-50 cm)
• Roux syndrome
  – Impaired gastric empyting without obstruction
  – Medical management
  – Last resort: Near-total gastrectomy with new
    Roux limb
• Case: 40 yo woman 7 days after Roux-en-
  Y gastric bypass has LUQ/epigastric pain
  and nausea. Patient has a palpable
  tender mass in the LUQ. CT
  demonstrates a dilated gastric remnant
  and duodenum.

• Diagnosis?
• Management?
  Late Post-gastrectomy problems
• Afferent Loop Obstruction
  – Pain after eating, relieved by projectile bilious
    emesis
  – Acute or chronic
  – Etiology: Adhesions, stenosis, volvulus,
    afferent limb too long
  – Treatment: Surgery (adhesiolysis, shorten
    afferent limb, convert BII to RY)
Other Gastric Pathology
• Case: 45 yo woman with long history of
  PUD on PPI presents with diarrhea
  epigastric pain. On endoscopy she is
  found to have multiple ulcers throughout
  her stomach.

• Diagnosis?
• Treatment?
   Zollinger-Ellison Syndrome
• Presentation: Abdominal pain, PUD,
  esophagitis
• Atypical PUD
  – Ulcers in atypical locations (distal duo/jej)
  – Multiple ulcers
  – Failure to respond to conventional treatment
  – Ulcers with diarrhea
                       ZE
• Dx
  – Serum gastrin level >1000 pg/ml diagnostic
    (off PPI)
  – Secretin-stimulation: check gastrin at 2,5,10,
    15, 30 minutes; increase more than 200 pg/ml
    diagnostic

  – DDX of hypergastrinemia: PPI, renal failure,
    G-cell hyperplasia, atrophic gastritis, retained
    or excluded antrum, gastric outlet obstruction
                     ZE
• Rule out MEN I (PPP)
  – Check serum calcium and PTH levels

• MEN I (25%)
  – Do total parathyroidectomy first
  – Medical management for metastatic
    gastrinoma – debulking has not been shown
    to enhance survival
  – Possible surgery for isolated gastrinoma
      ZE: Gastrinoma Triangle
• 70-90% located in
  triangle

• Junction of cystic
  duct/CBD
• 2nd/3rd portion of
  duodenum
• Neck/body of
  pancreas
      ZE: Tumor localization
• Octreotide scan (85% sens)
• Endoscopic ultrasound
• CT scan
               Treatment
• PPI
• Surgery for resection
  – Explore to find tumor and determine
    resectability
  – Local resection with lymphadectomy of nodes
    in gastrinoma triangle
  – Unresectable or gastrinoma cannot be
    identified: PCV
• Case: On laparotomy for a patient with a
  gastrinoma localized by octreotide scan,
  you cannot find the tumor.

• What are your options?
   Adjuncts to find gastrinoma
• Intraoperative ultrasound to examine duo,
  pancreas, liver
• Intraoperative EGD
• Transillumination with EGD
• Duodenotomy in proximal duo – palpate
  wall
    ZE: Postop considerations
• Follow patient with gastrin, calcium and
  PTH levels and octreotide scans
• Chemo: streptozocin, doxorubicin, 5-FU

• Prognosis: 15-yr without liver mets 80%,
  5-yr with liver mets 20-50%
• Case: 40 yo woman with DM, HTN, sleep
  apnea, chronic lower back pain, and
  arthritis who weighs 235 lbs and is 5’4”
  with a BMI of 40 presents to you. She is
  interested in weight-loss options.
A few words on bariatric surgery…
• NIH Guidelines
  – BMI > 40; or BMI > 35 with comorbidities
  – Failed previous attempts at nonsurgical
    weight loss
  – No active history of alcohol or substance
    abuse or uncontrolled psychiatric disease
  – Realistic expectations and commitment to
    followup
  – Acceptable risk for surgery
VBG
 • 40-50% EBW loss
   over 1-2 yrs
 • Pouch dilatation,
   staple line disruption,
   band migration, band
   obstruction common
 • Reop rate 30%
Gastric Bypass
       • 60-70% EBW loss
         over two years
Lap Adjustable Band
          • Allergan band FDA-
            approved in 2002
          • 40-50% EBW over 3-
            5 years
          • Complications: band
            slippage, erosion
          • Reop rate 10%
Biliopancreatic Diversion
             • Distal gastrectomy
             • Short common channel 
               50 cm
             • 80% EBW lost
             • Potential complications:
               severe protein-calorie
               malnutrition, fat-soluble
               vitamin deficiency,
               diarrhea, **marginal
               ulcers
Duodenal Switch
        • Pylorus is preserved
        • Can be 1- or 2- stage
        • Start with sleeve
          gastrectomy
        • Good for patients with
          scarring at GEJ
Gastric Neoplasms
• Case: 74 yo African-American man,
  smoker, who used to work in a coal mine
  40 years ago, presents with epigastric pain
  and weight loss.

• Workup?
            Gastric Cancer
• 10th most common malignancy in US
  – More common in males, African-Americans,
    Hispanics, Native Americans
• 2nd most common malignancy in world
  (after lung)
  – 75-100/100,000 in parts of Asia
  – 8-15/100,000 in US
                        Pathology
• 95% of US variety: adenocarcinoma
• Lauren classification
  – Intestinal
     •   Assoc with chronic H. pylori infection, gastritis
     •   Glandular
     •   Distal stomach more commonly affected
     •   Hematogenous spread
  – Diffuse
     • Poorly-differentiated
     • Arise from lamina propria, usu prox stomach
     • Lymphatic spread, early metastasis
• Most commonly located on lesser curvature
                 Risk Factors
•   Diet (smoked foods, low in fruits/veggies)
•   Smoking
•   Male gender
•   African-American race
•   Low socioeconomic status
•   Occupational hazards (metal, rubber)
•   H. pylori infection
•   Adenomatous polyps
•   EBV
•   HNPCC
• Presentation
  – Abdominal pain
  – Weight loss
  – Chronic blood-loss anemia
• Diagnosis
  – EGD
  – Staging: CXR and CT abdomen/pelvis,
    consider EUS, diagnostic laparoscopy
                  Staging
• AJCC/UICC Staging system
• T1-4 (submucosa-muscularis propria-
  serosa-adjacent organs)
• N0-3 (none, 1-6, 7-15, >15)
  – Need at least 15 nodes to N stage
• Stage 1 (T1N0-1 or T2N0), Stage 2 (T1N2,
  T2N1, T3N0), Stage 3 (T1-3N1-2, T4N0),
  Stage 4 (T4N1-3, etc.)
• Case: The patient has a 5 cm fungating
  antral mass which is adenocarcinoma on
  biopsy. On ultrasound it appears to be a
  T3 lesion.

• Management?
               R Status
• R0 – microscopically-negative margin
• R1 – macroscopically-negative margin
• R2 – gross residual disease
         Surgical Treatment
• Resection with en-bloc lymphadenectomy
  – 6 cm margin ideal

• Proximal tumors: total gastrectomy or
  esophagogastrectomy
• Midbody tumors: total gastrectomy
• Distal tumors: distal subtotal gastrectomy
• Local en-bloc organ resection only done to
  perform R0 resection
                 D Status
• Extent of LN dissection
• D1 – only perigastric nodes
• D2 – perigastric, hepatic, L gastric, celiac,
  splenic, and perigastric nodes > 3 cm
  away from primary tumor
• D3 – D2 plus porta hepatis,
  retropancreatic, and paraaortic nodes
• Case: Will you do a D1, D2, or D3
  dissection?
         Lymphadenectomy
• 5 prospective-randomized trials
  – South African trial: no benefit
  – Dutch trial: no benefit, more morbid
  – MRC trial: no benefit
  – Hong Kong trial: improved survival D3
  – JCOG: overall mortality 1% for D2 or D3
• No definite consensus
• D2 dissections considered investigational
  in USA
               Treatment
• Adjuvant: Chemo/XRT (5-FU/leucovorin,
  XRT)
• Neoadjuvant: investigational

• Palliative: resection, bypass, chemo/RT,
  laser recanalization, dilation, stents
               Prognosis
• Overall 5-yr survival 10-21%
• Recurrence 40-80% (usu. In first 3 yrs)
        Gastric Lymphoma
• Stomach: most common location for GI
  lymphoma
• RX: Chemo/XRT (controversial)

• MALToma: treat H. pylori
• Case: 50 yo woman complains of early
  satiety. CT of the abdomen/pelvis
  demonstrates a 5-cm well-circumscribed,
  vascular mass abutting the posterior
  stomach in the lesser sac.

• Diagnosis?
• Treatment?
             Gastric GIST
• 65% stomach, 25% small intestine
• Symptoms related to
  compression/displacement
• Radiologically-unique: vascular, well-
  circumscribed, closely-associated with the
  stomach on CT; intense uptake on FDG
  PET
• Bx not indicated (unless r/o lymphoma)
                Genetics
• C-kit proto-oncogene encodes KIT protein
  – Trans-membrane receptor tyrosine kinase
• KIT gene mutation in 75-90% of GISTs
• STI571 (Gleevac) selectively inhibits
  tyrosine kinases
• Response rate of 60% to Gleevac in
  metastatic GIST
                  Treatment
• Surgical resection: segmental en-bloc resection
  with negative margins
• Prognostic factors
  – Size
  – Histology (>5 mitoses/50 HPF)
  – Tumor location
• Follow with serial CT
• Gleevac only FDA-approved for
  recurrent/metastatic disease, other use in setting
  of clinical trial
          Recurrent GIST
• Gleevac
• Conventional chemo
• Consider surgery
Other Benign Pathologies
• Case: 18 yo college student has multiple
  episodes of hematemesis after binge
  drinking.

• DDx?
• Management?
             Mallory-Weiss
• Etiology of UGI in 5-15% cases
• Pathophysiology: acute increase in
  intraabdominal pressure
  – Forceful emesis
  – CPR
  – Blunt trauma
  – Childbirth
  – Straining for BM
• Usually a single tear involving the lesser
  curve below GEJ (50-80%)
• Co-existent with other sources of UGI in
  30-80% patients
• Resolves without surgery 90%
  – Endoscopy, angiography
• Surgery: High gastrotomy, oversewing
  – Check for other UGI bleeding points*
• Case: 80 yo woman wih chronic microcytic
  anemia presents to the ED with acute-onset
  chest pain. Cardiac workup is negative. She is
  retching but there is no emesis. CXR
  demonstrates a large gastric air bubble behind
  the heart and free air under the diaphragm.

• Diagnosis?
• Management?
             Gastric volvulus
• Present with
  abdominal pain,
  distention, UGIB,
  vomiting, retching
• Acute volvulus is an
  emergency
• Reduce volvulus,
  repair hiatal defect,
  gastropexy or tube
  fixation

								
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