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.


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