How a Urinary Infection Can Cause Diarrhea


Infections located anywhere from the kidneys to the urethra are called urinary tract infections. They are said to account for about 8 million hospital visits per year. They are usually caused by bacteria.

Predisposing factors are foreign objects in the urinary tract, like catheterizations, abnormalities in the urinary tract including congenital malformations and prostate enlargement, shorter urethra in women and diabetes mellitus.


Infective agents gain access to the urinary tract through a breach in the defenses. This is encouraged by any artificial presence in or around the lower urinary tract, like during passage of urinary catheters for any number of reasons or even use of contraceptive devices, especially the diaphragm. Sexual intercourse in some women, the short nature of the urethra and its proximity to the anus have also been implicated. Multiplication of the infective agents causes an intense tissue reaction resulting in pain (just above the pubic bone or at the back), burning or painful voiding, urgency, frequency and incontinence in some cases. A significant number of patients report diarrhea and a feeling of fullness in the rectum. Ascending infection and blood-borne infection, particularly in children, give rise to systemic symptoms of nausea and vomiting, fever and headaches. Multiplication of the infective agents is encouraged by stasis due to obstructive situations in urinary outflow like congenital malformations and prostatic enlargement or the peculiar situation of diabetes mellitus, where the excess sugar feeds the bacteria. Progression of the infective process leads to pus formation and local tissue damage, giving rise to pus and blood in the urine. Scarring in the kidneys could lead to irreversible damage and kidney failure.

Diarrhea in urinary tract infections

The urinary tract impinges directly on the digestive tract particularly where the bladder is in contact with the lower parts of the colon and rectum. Thus, an inflammatory process in the bladder will directly affect these structures. Theories include the heat resulting from the inflammatory process increasing motility in the intestines at points of contact or mediators of inflammation released in the urinary tract finding their way through locally shared blood pools to the digestive tract. The effect in either case will be increased secretions and motility in the intestines, leading to diarrhea.

The systemic upset seen in kidney involvement leads to nausea, vomiting and diarrhea. This is on a much larger scale as the entire blood stream has to go through the kidneys for filtration.


The delicate and vital nature of the urinary tract precludes symptomatic treatment. Prompt and adequate treatment prevents the development of complications that could be life threatening. The infective agent should be quickly isolated and adequate antibiotic treatment given. Diarrhea and vomiting in children without any obvious gastro-intestinal laboratory findings should warrant a check of the urinary tract.

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