I am sure that most women out there have had the pleasure of experiencing an extremely full bladder during a pelvic or obstetrical ultrasound examination!  The usual question that we get regarding this is “why do you need to torture us with an overly full bladder while you press on our pelvis making it worse?”

Well, there are two very good reasons that we do this.

pelvic ultrasound

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Before I give you the answers, let me give you just a small amount of ultrasound knowledge that will bring this all together. Ultrasound uses sound waves to produce cross sectional images of the organs in the body. These sounds waves travel at different speeds through different tissues within the body. When the speed changes going from one tissue into another, some of the sound waves are reflected back to the ultrasound probe and that allows the ultrasound unit to produce images. Most tissue speeds vary slightly but there is a drastic difference in the speed of sound between soft tissue structures in the body and gas.

Yes, all of us have gas!!!!

This results in all of the sound waves being reflected back to the probe not allowing us to see anything behind the gas. This is also the reason we need to use gel on the skin. It gives us a fluid contact with the skin surface allowing the sounds waves to enter the body. Sounds waves travel very well through fluid so the more fluid we have around, the better.

Now that I’ve made you a mini-ultrasound expert, let’s dive into why you need the full bladder.

The first reason is because you have gas!

Again, we all have gas and YOU are not exempt from that. As we discussed before, ultrasound cannot see anything behind the gas that is in your intestines. When you fill your bladder, it pushes the intestines out of the way making a clearer path for the technologist to see your uterus, ovaries, fetus and other structures we look for.

The second reason is that a full bladder is an excellent window for an ultrasound exam. Since sound waves travel easily through fluid, a full bladder allows them to penetrate deep into the pelvis to image the cervix on an obstetrical exam and the pelvic organs on a regular pelvic ultrasound.

In order for you bladder to be full for the optimal ultrasound examination, you must drink 32 oz of water 1 hour prior to your exam. DO NOT go to the restroom and empty bladder once you start drinking the water. We would also like you to eat a meal. If you do not eat, more water will be absorbed by your body and less will make it down into your bladder.

You now know the answer to one of the greatest questions of life, so please know that the technologist understands your discomfort. Now, you know the reasons why, too. Our technologists do not wish to torment, but for certain exams, that discomfort you feel is in your best health interests.

So, while we will torture you for a short while, but it is because we truly care about your health here at Diagnostic Imaging Services. We need you to be a little uncomfortable during the exam so you feel comfortable that you received the best possible care here at DIS.

— Craig Mailhos, Operations Manager, Diagnostic Imaging Services