A UTI can be limited to the bladder ("cystitis"), or it can spread upward to involve the kidneys as well ("pyelonephritis").  The latter is much more dangerous, as it can lead to permanent kidney damage. Unfortunately, while children get UTI’s less often than adults, when they DO get a UTI it is far more likely to progress into a pyelonephritis.  Cystitis generally does not cause a fever, while pyelonephritis usually does.  When a child with a UTI has fever, it should be treated as a pyelonephritis until proven otherwise.  This usually means admission to the hospital for IV antibiotics.  Cystitis, on the other hand, can be treated with oral antibiotics.

Diagnosing a UTI in a young child is no small or easy task.  Before they are toilet trained it really demands getting a specimen with either a catheter or a needle through the abdominal wall (a very safe procedure that is no more painful than any other shot but which is a "dying art" because nowadays pediatric residents aren’t forced to learn it as well as in the "old days").  A bagged specimen won’t "cut it", because it's too easily contaminated with germs from the skin (although a negative bagged specimen may be enough to rule out a UTI, a positive bagged specimen needs to be confirmed one of the above ways).

Once confirmed, a pre-pubertal child found to have a UTI needs to have a workup to check to see if their "plumbing" is put together right inside because, it turns out, just having that one UTI makes the odds about 30% that it isn’t.  (This in turn is at least part of the reason a child is more likely to progress into a pyelonephritis, and child in whom the first UTI is a pyelonephritis have an even higher, over 50%, likelihood of having an anatomic abnormality).  The possible plumbing problems and their treatment vary, but the most common one is called vesico-ureteral reflux (VUR).  In VUR the one-way valves which are supposed to exist where the urine enters the bladder are either absent or don’t work right, so that urine can go backwards up the pipes towards the kidneys.  This backwards flow not only makes the child more prone to UTI and pyelonephritis, but it also can cause kidney damage on it’s own via the pressure on the kidneys even without infection!  It is therefore an important diagnosis to make.  The studies which need to be done include (at least) an ultrasound of the kidneys and a voiding cystourethragram ("VCUG", in which the bladder is catheterized and a dye which shows on XR is used to fill the bladder then an XR movie picture is filmed of the child emptying the bladder into a diaper or bedpan) in a child whose first UTI occurs before the age of 8y.  Between 8y and puberty, an ultrasound by itself is enough.

Of course, we don’t want to have to do the above workup unnecessarily, so it becomes crucial that we be careful not to over-diagnose vaginitis as UTI.  For this reason we often send 2 cultures rather than 1 before starting treatment in a toilet trained child, and we never accept a positive bagged culture as proof of a UTI in a child who isn't toilet trained.

© 1996 by David A. Ansel, M.D.