Pyelonephritis and Pyonephrosis are easy as pie
Cause of confusion:
At first being introduced to nephrology the terms pyelonephritis and pyonephrosis are easily confused. The smart way to remember is to know that pyo- comes from the greek for 'pus' and pyelo- from 'trough', but just to make sure you're never among the confused, think PYO for pyonephrosis:
Pus
Yields
Obstruction
And to remember what to look out for in pyelonephiritis think PYELO:
Pain - ballottement soreness or flank-pain
Yellow - test urine, positive for leukocytes + nitrate
EPEK - Is an acronym of the most likely culprits in bladder infections, which are also found here although in different proportions - E. coli (50%), Proteus(5%)/Pseudomonas(5%), Enterococci (15%), Klebsiella (10%),
Light to heavy fever - depending on severity
Often unilateral
and just to go full circle, keep in mind that untreated pyelonephritis → pus → pyonephrosis
Background information:
Wikipedia (cystitis, pyelonephritis), p. 292 8th OHCM and pp. 469-472 21th DPPM