i'm oron frankel an emergency physician scanning the bladder can provide useful information in patients in whom i suspect urinary retention to perform the scan i use a c3 scanner on the bladder preset i start in the transverse orientation aiming deep into the pelvis to identify the fluid-filled structure of the bladder and i'll fan to maximize its diameter at which point i'll freeze the screen and when i go into my calculations i can quickly estimate the pre-void by just tapping on the bladder and i can just modify them to make sure i really like where they set up i save that image go back to scanning now into the sagittal plane i'll again maximize that diameter and this time i just have to freeze and click on the bladder calipers will pop up and i can make sure they really go to that maximal extension the app itself will calculate for me the pre-void residual of 564 cc's in this case and i can perform the same scan again post void to compare the two and see if there really is signs of urinary retention to help facilitate my diagnosis