Welcome to HCM and thanks for your query.
Having suspected the coil, it is wise to remove and see if she gets better.
If not, she needs ultrasound
scan to check the residual urine and uroflowmetry to check the flow of urine.
Of course, renal function needs to be assessed by a simple blood test
. All these can be done under the guidance of the urologist
, who you are going to see soon.
Hope this helps.