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NPO, or Nothing by Mouth: 3 Things You Need to Know

NPO, or Nothing By Mouth: 3 Things You Need to Know

When your doctor tells you to follow NPO for a medical imaging exam, it means you cannot eat or drink anything for a certain period of time before your exam. There are different reasons your doctor may instruct you to do this. Likewise, the reason for and length of the “fast” varies from case to case. Learn the 3 things you need to know about NPO.


1. NPO Means “Nothing by Mouth”

NPO means “nothing by mouth,” from the Latin nil per osThe acronym is simply a doctor’s shorthand for a period of time in which you may not eat or drink anything (ask about prescription medication).

Fasting is generally prescribed in preparation for an operation or exam. In medical imaging, doctors usually order it for CT scans that use iodine-based intravenous contrast or for exams that use sedation.

2. NPO is a Safety Precaution

NPO is usually prescribed as a safety precaution. Without it, you could become nauseous once contrast or sedation is administered because you have something in your stomach. This can lead to aspiration meaning you might uptake your stomach contents into your lungs. Aspiration can lead to pneumonia and other health issues.

To avoid potential safety concerns, abstaining from eating or drinking is recommended for children and adults receiving certain kinds of sedation or contrast.

3. The Length of Time Varies

For some exams and procedures, nil per os starts an hour before the exam.  For others it can start as early as midnight the night before the exam. You will receive special instructions for NPO based on the exam you are having.

Fasting and You

The most important thing you can do to prepare for your medical imaging exam, operation or procedure is to follow your NPO instructions as closely as you can. This will keep you safe during the procedure, or eliminate the need for any delay or repeat in testing.

As always, speak with your care provider if you have questions or concerns about not eating or drinking before your exam, or other aspects of your exam instructions. And click here to learn more about screenings and procedures performed by UVA Radiology and Medical Imaging.


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3 Things You Need to Know About NPO

  1. NPO means “nothing by mouth;” it refers to the time before an exam or procedure during which you can’t eat or drink.
  2. NPO is a safety precaution: if your stomach isn’t empty and you get nauseous during a procedure, your stomach contents can flow into your lungs.
  3. The length of time varies: NPO can begin at midnight the night before an exam, or as little as an hour before. It depends on the specific procedure or exam you are having.

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