The patient is told that he/she should not eat or drink anything for 4 hours in advance of having an echo (except from drinking pure water).

From what I understand, an echo works with ultrasonic sound. Would the echo really be able to see a difference depending on what beverage one drinks?

The purpose of the echo is to check for gall or kidney stones (in case that has anything to do with the matter).

  • 1
    I assume you mean ultrasonography with echo?
    – Narusan
    Commented Nov 30, 2017 at 14:29
  • Yes, thanks @Narusan-sedated I guess that would be the correct official name. In the Netherlands we simply call it "echo". Commented Dec 1, 2017 at 15:36
  • If they're looking your GI tract, the presence of food could easily interfere with or confuse the results.
    – Carey Gregory
    Commented Dec 2, 2017 at 2:27

1 Answer 1


There are two major issues with eating.

  1. Swallowing and digesting food allows air to get into the digestive tract. Air is a barrier to the ultrasound waves so renders tissues distal to the air invisible as the ultrasound will reflect off the tissue air interface
  2. Food can cause the gall bladder to contract pushing its contents into the small bowel. A contracted gall bladder is not easily identified

Carbonated beverages are also not advised due to the CO2 bubbles that form and release which can interfere with ultrasound interpretation.


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