First, let’s quickly review why we ask for a full bladder.
When you’re lying on your back, your uterus either tilts up towards your belly button (anteverted), or back towards your spine (retroverted). Most women are anteverted.
Between your uterus and your abdomen is the bladder. So, when you have a full bladder, it tends to tilt that upward-tilting uterus back the opposite way, forcing it to temporarily have a nicer, flatter surface. Why is that good? Because during an ultrasound, sound waves have to bounce off your uterus. A “flatter” uterus means a clearer image, so the ultrasonographer can get a much better visualization of your uterus and the lining.
But it also helps for any clinician doing a procedure like endometrial biopsy, or an intrauterine insemination, or an IVF embryo transfer. In these procedures, a rather rigid catheter is being placed into the cervix, and if it can then go in a straight line, it’ll be much more comfortable for you. It’s also easier for the clinician to place the catheter in the exact location needed.
But there’s a fine line between having a full bladder and having an excessively full bladder. The standard advice on how much to drink may not work for you, since everybody is different.
Some women have high urinary frequency; that is, they urinate all the time. They tend to have smaller bladders, which therefore feels “filled up” much faster. Other women are more used to holding their bladder, and they become stretched out, and they can have very large bladders.
So, what do you do if you’re waiting with a too-full bladder? You know it’s too full if you’re pacing and there’s sweat on your brow. You need to let some urine out.
I promise you, it’s not of any value to you or the clinician to have a too-full bladder. The pressure from an ultrasound being placed on your stomach, or a speculum being placed for a procedure, would be uncomfortable or even impossible for you if your bladder is too full.
So go to the bathroom! But don’t completely empty your bladder. Sounds impossible? It isn’t. Take one of the styrofoam cups that many clinics have for drinking water to the bathroom with you, and stop urinating when it’s full. That should be enough to give you relief and keep your bladder full enough for the clinician.
What if you have a retroverted uterus? For these women, a moderately full bladder can help with ultrasound, but not with the procedure itself. If you know you have a retroverted uterus, don’t make yourself miserable trying to have a full bladder. It won’t tilt the uterus or make a difference.