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4. TYPE of gastric content

Gastriccontenttable

Empty stomach

  • The antrum has no appreciable content in both supine and RLD (Grade 0 antrum)
  • It appears flat and collapsed or with a round-to-ovoid shape (“bull’s eye” or “target” pattern)

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fig1

A: antrum; Ao: aorta; D: diaphragm;  L: liver; P: pancreas; R: rectus abdominis muscle; Sma: superior mesenteric artery

solid EARLY STAGE

  • The antrum appears distended with thin walls
  • The content is of high or mixed echogenicity
  • Specific patterns:
  • “Frosted-glass” pattern (usually shortly after a solid meal). It is due to a mix of air and solid along the anterior wall, blurring the posterior wall and deeper structures

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fig4

A: antrum; Ao: aorta; L: liver; R: rectus abdominis muscle

solid late stage

  • Heterogeneous, particulate content (usually after 1-2 hours following a solid meal)
  • Homogeneous hyperechoic content: characteristic of dairy products or particulate fluids

 

  • Milk curdles and can have a typical biphasic (hyperechoic/hypoechoic) appearance (see additional material)

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fig5

A: antrum; Ao: aorta; L: liver;  P: pancreas; R: Rectus Abdominis muscle; S: spine; Sma: superior mesenteric artery

 

Clear fluid

  • The antrum is round and distended with thin walls
  • The content appears anechoic or hypoechoic
  • The size of the antrum is proportional to the gastric volume
  • The antrum will appear larger in the RLD compared to the supine position

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fig2

A: antrum; Ao: aorta; D: diaphragm; L: liver; P: pancreas; R: rectus abdominis muscle; S: spine; Sma: superior mesenteric artery

fluid WITH AIR BUBBLES

  • Special pattern:
    • “Starry night” (multiple air bubbles on a hypoechoic background) usually seen shortly after ingestion of clear fluids or effervescent drinks
  • A volume assessment can differentiate a low (normal) quantity of baseline gastric secretions from a higher (non-fasting)volume

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fig3

A: antrum; Ao: aorta; L: liver; P: pancreas; R: rectus abdominis muscle; S: spine; Sma: superior mesenteric artery