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Why does scar tissue form in the kidney after pyelonephritis heals?

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The most common cause of urinary tract infection is invasion into the urethra of Escherichia coli, a type of bacterium that normally inhabits the bowel. — urinary tract infection The most common cause of urinary tract infection is invasion into the urethra of *Escherichia coli*, a type of bacterium that normally inhabits the bowel.

In the context of pyelonephritis, scar tissue forms as a natural consequence of the healing process following inflammation and infection of the kidney tissue.1

During an acute infection, abscesses may develop within the kidney, and some nephron tubules—the structures responsible for producing urine—can be destroyed. As the body works to resolve the infection and repair these damaged areas, the affected tissue is replaced by fibrous scar tissue. While the body typically retains enough healthy tissue to maintain normal renal function after a single acute episode, repeated or chronic infections can lead to the progressive destruction of functional tissue, eventually resulting in a state where the amount of scar tissue significantly outweighs the remaining healthy, functional kidney substance.1