I work in the Operating Theatre and often see patients with MS coming to theatre to have these catheters(they are called suprapubic) and are placed into the bladder via a tiny incision halfway between the urethra(where you normally pee from) and the umbilicus(belly button). They are usually the best option as they are easier for maintenance and managing by the patient.
If your friend sees the consultant urologist at her local hospital I'm sure she'll be well advised and have her mind put at ease as well as sorting out her urinary problems.