Are UTIs dangerous?

Most UTIs can be treated routinely with antibiotics if detected early. However, if a UTI is left untreated, it can spread to the upper urinary tract which contains the ureters and kidneys. An infection in the kidneys (pyelonephritis) may 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 is a one-way valve at the end of each ureter that prevents the contents of the bladder from entering the ureters. That is one reason why upper UTIs are far less common than lower UTIs.