ER may not be the right place. The reason is; doctors are interested to just find out if one has a life threatening illness. Otherwise they may not investigate properly. Your primary care physician or a urologist would be the best to do the work up for it. We divide UTIs into anatomic/structural abnormalities and functional abnormalities.
Anatomic abnormalities include kidney swelling, cystocele (bladder prolapse), and stone disease. This can be evaluated with a good rectal exam, CT scan of the abdomen and pelvis with and without contrast, and cystoscopy (telescope inside your bladder).
Functional abnormalities include high pressure voiding or incomplete emptying of your bladder. Urinary infections are often due to incomplete emptying of the bladder or high pressure voiding and these are best checked with a urodynamic study (pressure flow study done by a urologist to see how your bladder fills and empties) and voiding cystourethrogram (contrast study by radiologist to see how your bladder empties).
If you have not imaging of your kidneys, cystoscopy, and a urodynamic study, it may be wise to consider.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.
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