Four days sounds real short to me... If it comes out early you end up in the ER Friday night to get a cath put back in.
The following is the $750 to $1000 test you asked about. I had 3 or 4 of them and my cath ended up being in for five weeks.
Cystogram
A cystogram is an x-ray examination of the urinary bladder, which is located in the lower pelvic area. A cystogram can show the bladder's position and shape, and the exam often is used to diagnose a condition called reflux. Reflux occurs when urine in the bladder moves back up the ureters, the tubes that transport urine from the kidneys to the bladder. This condition can cause repeated urinary tract infections. A cystogram may be performed after a patient has experienced a pelvic injury to ensure that the bladder has not torn. Cystograms also are used to detect polyps or tumors in the bladder.
https://www.asrt.org/content/ThePublic/aboutRadiologicProcedures/Cystogram.aspx