Gastric Outlet / Duodenal Obstruction
DEFINITION
Obstruction to the gastric outlet
including pylorus or duodenum leading to vomiting, electrolyte and
acid/base imbalance and inability to eat, due to a range of possible
causes.
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INCIDENCE
As per causes below
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AETIOLOGY
PUD.
- if close to pylorus; not a common complication in modern era
- most have longstanding PUD / symptoms
- typically due to DU and not GU, but occasionally recurrent GU
Cancer
Common cause of obstruction
Any cancer of the area can do this.
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BIOLOGICAL BEHAVIOUR
Pathogenesis
PUD: chronic inflammation --> oedema, spasm, and ongoing
scarring and fibrosis causes stricture of the pylorus.
Electrolytes
Lose K+, H+ and Cl-
- Extracellular HCO3- rises
- Kidney excretes HCO3- to maintain pH
--> Na+ follows the HCO3- out
--> Aldosterone secretion
--> Primacy of sodium leads to loss of more K+ and H+ from renal
tubules in return for retained Na+...
End result is dropping GFR, marked deficits of Na+, Cl-, K+ and H2),
and alkalosis.
--> Treat with NaCl until urine flowing, then replace K+.
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MANIFESTATIONS
Symptoms
Local
Prolonged continued vomiting.
- Lack of bile staining
Systemic
Dehydration.
Hypochloraemic, hypokalaemic metabolic alkalosis.
Malnutrition.
Signs
Palpate
Possibly epigastric mass.
Auscultation
Succussion splash (Hippocrates).
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INVESTIGATIONS
Endoscopy
Confirmatory
XR
Large gastric fluid level
CT with oral contrast
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MANAGEMENT
Basic
Large (32F) drainage tube --> empty, lavage until clean, then
replace with a smaller tube on free drain
"Saline load" test may be useful (load 750 ml then see what is
returned in 30min)
PPI and IV fluid replacement.
K+ and N Saline for losses.
Therapeutic balloon dilation or stenting
- can buy time but should not replace definitive surgical management
Surgical
As per specific causes
In PUD:
Antrectomy is procedure of choice.
Scarring may preclude a Billroth I
If concern re stump leak in a Billroth II
- then may need diverting gastrojejunostomy.
Stenting
Modern approach to duodenal obstruction is stenting. Better
outcomes across multiple categories.