The Ultrasound Bladder Prep

Why do I have to drink a sea of water?

ultrasound bladder prep

To drink or not to drink! That is the dilemma, and the facility performing your test has the answer to your ultrasound preparation questions. Being required to fill your bladder depends on a few factors…how far along you are if you’re pregnant, the type of ultrasound exam performed, and the protocols of your doc’s office, hospital, or out-patient center where the ultrasound will be conducted. The protocol or policy for how to conduct your test varies from place to place.

I know what you might be thinking. Every site says something different. You’ll find the most comprehensive info here. Why? Because I performed these tests for years. The info here is accurate, and reflects most all scenarios. However, at the end of the day, the facility where the exam will be performed should be able to tell you exactly what ultrasound preparation they want you to follow. And only what they say matters!

The Prep

The dreaded bladder prep may vary a little from one place to the next, but goes something like this:

  • Empty your bladder 1.5 hours prior to your exam
  • Drink 32ozs of fluid (preferably nothing carbonated) within 30 minutes
  • Have all fluid down 1 hour prior to your exam
  • Do not pee until exam is complete! 😩😵

To clarify, let’s say your appointment is 10am. You will pee at 8:30am, drink from 8:30 to 9am, and have all the water down by 9. Most bladders require the full hour to fill completely. Do not pee before your appointment time! This action, of course, defeats the whole purpose for drinking, but you would be suprised at how many do.

Will you feel like you have to pee before this hour is up? Oh, yes ma’am! Not many people allow their bladders to fill to this capacity before they feel the urge to tinkle. It might very well feel like the L O N G E S T hour of your life.

Don’t even look at one of these: ultrasound bladder prep

Or listen to this:

ultrasound bladder prep

And you’ll definitely want to steer clear of one of these:

ultrasound bladder prep

I promise. You won’t be happy if you don’t!

There is a bit of good news to all this. Once full, the exam (for a very experienced sonographer) is pretty quick . . . 5-10 minutes in most easy-to-see negative cases.

But Why a Full Bladder?

ultrasound preparation

Full bladder pelvic ultrasound

Blame the laws of Ultrasound Physics for this one. Sound waves travel more easily through fluid than tissue. Think of your pelvic anatomy from front to back. First is skin, then fat, then muscle, then intestines or bowel, then your bladder. Your uterus sits behind your bladder. So, if you drink lots of water and fully distend your bladder, it provides a window to the uterus. Also, your bowel contains air and gas which can limit what we see. Filling your bladder pushes the intestines aside. It’s actually kinda cool, but not so much if you’re the one doing the drinking.

Additionally, the uterus of most women tilts forward (anteverted) or toward the front of your belly. Filling the bladder aids in pushing the uterus backward a little–not up or higher, as I’ve read in some pregnancy books or sites, though that phrasing is really just a technicality. When the top of the uterus tilts back a little, a better angle is created to see more clearly. Occasionally, a uterus decides to go rogue and tilts too far backward instead (retroverted). Sometimes it tilts so far back that it folds over on itself (retroflexed). This is a totally normal variant. Often, however, the full bladder only helps minimally in these circumstances.

Transvaginal Ultrasound (Endovaginal) Approach

TV probe, how much water to drink for your ultrasound

Whether you are pregnant or not, the rules are the same for a transvaginal ultrasound exam. An empty bladder is required. The TV provides a more magnified view, so a full bladder just gets in the way. Inside the vagina, the probe is closer to your organs allowing us to see them more clearly. AND we don’t have to fight to see past your bowel like we do with the belly approach.

If you’re early in your first trimester, usually less than 11 or 12 Weeks, you will (9 times out of 10) have a TV. This is, BY FAR, the best way to see so early because Baby is so tiny. If your uterus is enlarged with fibroids (very common muscle tumors), your sonographer may try to scan you with TV first. However, if your uterus is too large to see well with the TV probe, she may end up attempting the abdominal approach. If this happens, you may or may not need to drink. Quite often, we can see what we need without making you drink an ocean of fluids.

I can’t speak for all private practices, but we only required a bladder prep for some GYN studies. Only those who were not sexually active or refused the TV exam needed to fill!

Trans-Abdominal Approach

In most hospitals and out-patient imaging centers, you’re going to be drinking, sister! Your exam is typically read by a radiologist in these facilities.

Most of the time, radiologists are of the mindset that certain anatomy will be better seen with a full bladder EVERY time and on EVERY patient. This isn’t necessarily true, but most of these docs want to start with a full bladder first. Commonly, they’ll have you empty for a vaginal scan if they want a better look. To be fair, I haven’t worked in the hospital setting in 15 years. Maybe they’ve adopted more modern policies! If they haven’t, they should.

Filling the bladder has long been the standard practice, and radiologists are set in their ways (sorry, guys, you know you are!). They like to start with a full bladder, but the experienced sonographer knows how best to scan to obtain the images needed. I think the protocol should be opposite . . . TV first and only make the patient fill if absolutely needed! Unfortunately, I don’t make their rules.

Many of these places will also still require you to fill for your anatomy scan at 18-20 Weeks or even for ultrasound exams in the 3rd Trimester. In my opinion, that’s just pure evil. Expectant moms have enough pressure on their bladders as it is! A little fluid in the bladder may help us to evaluate the cervix. But most patients have a little fluid in there anyway. In cases where the cervix isn’t seen well, our friend, the TV probe, is called to action.

Cons to Filling the Bladder

  • Elderly patients (for GYN exams) have a hard time holding their urine
  • Most OB patients have a problem holding it due to pressure from Baby
  • Drinking the water too fast often causes the patient to vomit it right back up!
  • Many do not follow the ultrasound preparation properly. They either do not drink enough water, they don’t have it down in time, they drink more than they needed which results in over-filling the bladder, or they drink all the water then pee right before the exam
  • Not following the prep usually results in drinking more fluid or being rescheduled
  • Some say they weren’t given a prep
  • Sometimes schedulers really do forget to provide the instructions
  • Some patients are dehydrated, so the fluid tends to go where it’s needed and not the bladder
  • But most importantly, it’s MISERABLY painful for the patient!!

In my opinion, the cons far outweigh the pros for drinking water for an ultrasound exam. However, your facility could care less what I think and dictates what ultrasound preparation they want you to do for your test! Being able to pee when you want is a luxury. You just don’t realize it until somebody tells you that you can’t! When in doubt, ask if you’re free to pee!

Best wishes for a healthy sonogram (with no bladder prep🤞)!

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your questions here.

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