Download Basic Science: Stomach

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
• 4 types, varying
etiologies
• 75% HP
• NSAID history more
common
• Usually older patients
• DUODENAL ULCER
• Usually associated
with excess acid
production
• 90% HP
Type 3
Type 1
Type 2
Type 4
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 NSAIDdependent
• 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 Rouxen-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-enY 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 FDAapproved in 2002
• 40-50% EBW over 35 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 propriaserosa-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, wellcircumscribed, 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