What risk does a UTI pose?
Most UTIs involve the lower urinary tract which consists of the bladder and urethra. Infections in the urethra (urethritis) or in the bladder (cystitis) are fairly common, and if detected early can be treated routinely with antibiotics.
However, if a UTI in a child is left untreated, it can spread to the upper urinary tract which contains the ureters and kidneys. An infection in the kidneys (pyelonephritis) can lead to permanent scarring of the kidney tissue. Excessive scarring of the kidneys reduces their ability to function and can lead to high blood pressure (hypertension) or even complete kidney failure.
Fortunately, it is not easy for the bacteria to gain access to the ureters and kidney because, in healthy children, there are one-way valves at the end of each ureter that prevent the contents of the bladder from entering the ureters. That’s one reason why upper urinary tract infections are far less common than lower urinary tract infections.