The prefix of pyelonephritis is "pyelo-".

Pyelonephritis is often associated with the reflux of urine from the bladder to the upper urinary tract

The diagnosis of pyelonephritis is based on the patient's history, a physical examination, and the results of laboratory and imaging tests

Urinary retention can predispose someone with MS to urinary tract infection, including pyelonephritis.

Acute pyelonephritis is most common in adult females but can affect people of either sex and any age