Preparing for your scan

To fast or not to fast

According to Urban Dictionary, fasting is defined as when you consume no food or drinks, with the exception of water.

This entry was written because we had patients who fasted when they didn’t need to. And those who needed to fast didn’t do so. We are here to clarify this state of unsureness for better scan preparedness which in turn affects image quality and hence, diagnosis.

Abdomen scans

Fast at least 6 hours

Scans of the abdomen region comprise of any scan which includes images of the gallbladder, namely:-

  • US Abdomen
  • US Hepatobiliary System
  • MRI Abdomen
  • MRI Liver
  • MR Cholangiopancreatography
  • MRI Pancreas

Reason for fasting
The reason you need to fast before your abdominal scan is so that the gallbladder, a pear-shaped organ beneath your liver, remains distended just like an inflated mini balloon. An inflated mini balloon state of the gallbladder is necessary so accurate assessment of the inside of the gallbladder and its wall can take place. We assess the gallbladder for presence of stones, inflammation, small growths and cancer. If the gallbladder is ‘deflated’, it is difficult to check for these conditions as you would have already figured out.

Distend your gallbladder
Your gallbladder stores bile, a thick, yellow-green fluid produced by your liver. Before a meal, your gallbladder is filled with bile and looks like a mini balloon. After a meal, your gallbladder becomes empty and flat, like a deflated balloon. This is so because your gallbladder has emptied all the bile into the bile ducts which drain bile into the small intestine to aid digestion of food.

In a nutshell
For those preparing for an abdominal scan, do remember to fast. We really need to see that inflated mini balloon.

For those going for a non-abdominal scan that is those not listed above, no need to fast. Save yourself from some hunger.

Pelvis and prostate scans

US pelvis and prostate
Fill up your urinary bladder

It is important to drink at least 500 – 700 mls of water 1 hour before an US pelvis, for females or US prostate, for males. If you don’t drink, we will know because we first check if your urinary bladder is full when you arrive and this is done using ultrasound. So, don’t lie about having drank a gallon of water if you haven’t.

A water-filled urinary bladder will be distended just like a balloon, and is essential when doing an ultrasound, to enable us to see the womb, ovaries or prostate more clearly. The distended water-filled urinary bladder serves 2 functions in this scenario – i) as a ‘window’ to better visualise the womb, ovaries or prostate ii) in females, helps lift the womb and push away bowels for better visualization of the womb and ovaries.

Do not empty your urinary bladder until we tell you to!

US urinary bladder
Fill up your urinary bladder

Ultrasound of the urinary bladder will be part of the urinary tract examination which includes the kidneys. Just like the gallbladder, we need a distended urinary bladder filled with water to have a good look at the inside of this round pouch-like organ and its wall for stones, inflammation and cancer.

MRI pelvis and prostate
Empty your urinary bladder

In contradistinction to US pelvis and prostate, for MRI of these same regions, you have to empty your urinary bladder before your scan. This is to avoid artifacts that may arise from urine flow within the urinary bladder, the latter very closely related to your reproductive organs.

* US = Ultrasound * MRI = Magnetic Resonance Imaging
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