Once the kidneys filter blood, urine is produced. The urine then passes down the ureters (tubes leading from the kidneys to the bladder) and is stored in the bladder. Bacteria from the stool, which may colonize the area around the rectum and vagina, sometimes move in a retrograde (backwards) fashion up the urethra (the tube leading outside from the bladder) into the bladder. If the bacteria stay in the bladder, they cause inflammation called cystitis. If the bacteria are able to move up the ureters into the kidneys, they may cause a more serious infection called pyelonephritis.
Both require prompt treatment with antibiotics to avoid the condition getting worse or damage to the kidneys. When a child has a UTI, there is a 30-50 percent chance that the urinary tract is abnormal in some way. Therefore, once the infection is cleared, the child requires an evaluation to look for abnormalities in the urinary tract (even if this is the first episode of infection). Possible findings could be vesicoureteral reflux, obstruction, urinary stasis (stagnation) or even a stone. . The urologist will choose from an array of diagnostic tools including renal ultrasound, voiding cystourethrogram, CT scan, or cystoscopy coupled with a special radiographic study known as the PICC test (positioning and instillation of contrast cystography) to identify the offending condition either causing or contributing to the infection. If an abnormality is identified, further testing may be done, and then correction of the condition or medical therapy will be proposed. Continued treatment by the pediatric urologist is then individualized and tailored according to the findings of the work-up.