Editing Gastric outlet obstruction

== Aetiology ==

* Previously mostly benign, but     with the improved treatment of PUD, now 50-80% malignant
* Malignancy
** 35% gastric CA
*** Adenocarcinoma 90%
** 20% pancreatic CA
** Gastric lymphoma
*** Most common of GIT       lymphomas
*** Treat with CTX alone
** Gallbladder CA with local      extension
** Duodenal CA - primary or      mets
** Gastric carcinoid
** GIST
*** Interstitial cells of Cajal
* Benign
** Intramural
*** PUD - rare complication       (<5%)
**** Acutely - inflammatory        swelling, accompanied by duodenal peristaltic dysfunction
**** Chronically - scarring at        gastric outlet
**** Manage with medical        therapy (PPIs, avoid risk factors), then endoscopic pneumatic dilation,        then surgical (truncal vagotomy)
*** Crohn's - 5% show       gastroduodenal involvement
**** Proximal Crohns =        nonspecific gastritis type symptoms
*** Pyloric stenosis
*** Caustic injury due to       poison ingestion
**** Occurs due to fibrosis,        6-12 weeks post injury
**** Incidence 5-10% after        caustic ingestion
*** Gastric TB
*** Gastric volvulus - seen in       older adults, generally related to hernia (greatest risk type III)
**** Borchardt's triad - sudden        epigastric pain, intractible retching/vomiting, inability to pass NGT
**** True surgical emergency
**** CT - GOO with abnormal        location of gastric outlet, non-passage of enteric contrast material,        gastric wall thickening, adjacent fluid or fat stranding
**** CR - NGT coiled in gastric        body, which is located in chest
**** Upper endoscopy can be        both diagnostic and therapeutic
*** Post-surgical complications
** Intraluminal
*** Bouveret syndrome - pyloric       impaction of a gallstone
*** Large gastric polyps
*** Bezoars
*** PEG migration
** External compression
*** Acute/chronic pancreatitis       - 1-5% show GOO
**** Can occur with        peripancreatic fibrosis or giant pseudocyst
*** Annular pancreas
** Dysmotility

== '''Pathophysiology''' ==

* Often see hypokalaemic,     hypochloraemic metabolic alkalosis
** Loss of gastric juice rich      in hydrogen, chloride and potassium
** Hypovolaemia causes ADH      activation which causes hyponatraemia
** Hypovolaemia and      hyponatraemia activates RAAS
** Kidney tries to correct      hyponatraemia by exchanging sodium for hydrogen and potassium ions (under      stimulation of RAAS), causing paradoxical aciduria and worsening      alkalosis/hypokalaemia
** Hypokalaemia is due to      gastric and renal losses as well as intracellular shift to maintain      membrane polarity

== '''Clinical manifestations''' ==

* Nausea/vomiting - with     undigested foodstuffs from days previously noted
** No bile staining in vomit
* Epigastric pain -     particularly post-prandial, and relieved by vomiting
* Weight loss
* Early satiety
* Abdo distension
* Examination
** Succussion splash
*** Listen to abdomen while       shaking patient from side to side
*** Pathologic if heard >3       hours post meal
** Virchow's node/sister mary      joseph node

== '''Investigation''' ==

* Electrolyte abnormalities as     above
* Plain film - enlarged gastric     bubble
* Barium swallow - can show a     complete obstruction, if no contrast in small bowel

== '''Management''' ==

* Not a surgical emergency -     aim to resuscitate, diagnose then treat
* NBM + IVF
** Normal saline + potassium      good for treating hypokalaemic, hypochloraemic metabolic '''alkalosis'''
* NGT
* Electrolyte replenishing
* PPI
* Endoscopy - rule out     malignancy and assess for H. pylori infection
* Consider TPN + nutritional     assessment
* Further management depends on     cause

== '''Gastric outlet obstruction secondary to PUD''' ==

* Results from chronic     inflammation and scar formation
* Medical treatment
** As above, with endoscopy and      H. pylori testing
** May be able to be treated      conservatively, with oedema improving over time
* Endoscopic treatment
** Endoscopic dilation +/-      stenting is the mainstay of therapy
** Novel techniques - US-guided      gastric bypass and POEM
* Surgical treatment
** Indications:
*** Obstruction refractory to       endoscopic treatment
** Gold standard operation is      vagotomy and antrectomy
** Other procedures
*** Bilroth II
*** Vagotomy with either       Jaboulay gastroduodenostomy or gastrojejunostomy

== Gastric resection ==

* May be able to just do a     wedge resection
* Malignancy - if aiming for     cure - oncologic gastric resection with wide margin
** Distal stomach - needs a      distal gastrectomy with a 6cm margin of normal gastric tissue
** Billroth II technique      preferred (decreased likelihood of obstructino with recurrence at      anastamosis)
**

[[Category:UGIS]]