“Do I need a full bladder for an anomaly scan”, will be the first common phrase from the receptionist when someone books an appointment for pregnancy or gynecological ultrasound. What is the medical science behind this simple but occasionally haunting request? This blog is all about it.
Can an anomaly scan be done on an empty stomach? Do you need a full bladder for an anomaly scan?
No, you should never have a scan on an empty stomach. You may need to arrive for the appointment with a full bladder. This should be specified when scheduling your appointment.
The secret unraveled – How do ultrasound machines work?
Ultrasound machines produce and receive sound waves. These waves have a very high frequency that the human ear cannot detect.
When an ultrasound probe is placed on or in your body, sound waves are transmitted through your body. Sound waves travel through your body, passing through organs and structures on their way.
There are numerous parallels between sound energy and light energy. Both can be reflected, resulting in an echo in the case of sound, or refracted, resulting in a change in the transmission path.
In ultrasound examinations, sound waves that are reflected or bounced back (echo) are very important. The echo is used to make a diagnosis. The ultrasound machine can amplify and process these echoes and, with the help of a special computer, generate an image of the body part being scanned on a video screen that can be saved, such as baby parts, uterus, ovaries, and so on.
After the computer has analyzed these echoes, the distance, size, shape, and consistency of the target organ can be determined.
In summary, an ultrasound machine operates in the following cycles:
What is the benefit of having a full bladder for the anomaly scan?
The primary goal of any examination is to transmit as much sound energy as possible in order to receive a good echo, which may lead to better images. The use of ultrasound gel aids in sound transmission.
Different body tissues or organs have different inherent sound transmission tendencies. Fluid-filled body cavities transmit sound well, whereas gas-filled organs, such as the bowel and lungs, transmit sound poorly. There is better transmission and better echoes in fluid-filled cavities, but poor transmission and weak echoes in gas-filled organs.
A full bladder is beneficial to the sonographer in several ways:
- Sound energy is increased at the target organs when it is transmitted through the bladder, such as the baby, cervix, uterus, ovaries, and so on. Because the round trip of sound energy has little resistance to transmission, this results in good echoes and better, more crisp images on display.
- Air is an excellent ultrasound beam reflector. The bowel is prone to becoming clogged with intestinal contents and gas. If the bowel is in the way, almost all of the sound will be reflected before reaching the region of interest, making good sound transmission to target organs nearly impossible. A full bladder aids in the transmission of ultrasound to target organs by pushing the bowel out of the pelvis.
- Most women have an anteverted (forward-tilted) womb, which, in some cases, does not present the optimal angle to the sound transmission pathway. A full bladder causes the womb to tilt backward, presenting a more favorable angle to the transmitted sound energy, resulting in better images.
How much water should be consumed for the anomaly scan?
Bladder capacity and behavior differ between individuals. Drink enough fluid to keep your bladder comfortably full. If your bladder is not adequately full or is very full and causing great discomfort, both of these conditions may have a negative impact on the examination.
Depending on your ultrasound expert or fetal medicine specialist, a full bladder may not be required for all examinations. Most early pregnancy ultrasound scans and up to 22-24 weeks may require a full bladder, but after that, it may not.
Because the ultrasound probe is much closer to the region of interest during vaginal gynecological scans, a full bladder is usually not required.