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Urinary tract infection

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of urinary tract infections.

Alternative Names

Cystitis; UTI

Complications

Urinary discomfort and emotional distress are the primary concerns in most women with recurrent UTIs. One study reported significant impairment of a woman's quality of life during symptom periods, which affected social function, vitality, and emotional well being.

Medical Complications of Urinary Tract Infections in Adults

Nearly all urinary tract infections are mild, treatable, and have no long-term consequences. Serious physical complications can occur in some cases, however, most often in hospitalized patients.

Obstruction and Widespread Infection. Very severe upper urinary tract infections may cause obstruction that results in widespread and even life-threatening infection. Patients who develop UTIs in the hospital are at higher risk for such infections than those outside the hospital. In one particularly dangerous form of kidney infection that obstructs the ureter, mortality rates exceed 40%. This specific condition should be suspected in people with diabetes who have severe UTIs.

Kidney Damage. In high-risk adults, recurrent UTIs may cause scarring in the kidneys, which over time can lead to hypertension and eventual kidney failure. People with UTIs who develop serious kidney disease from UTIs are likely to have other predisposing diseases or structural abnormalities. (Recurrent urinary tract infections, even in the kidney, almost never lead to progressive kidney damage in otherwise healthy women.)

Urge Incontinence. Recurrent UTIs may increase the risk for urge incontinence after menopause. (People with urge incontinence experience leakage and the need to urinate frequently.) [For more information, see In-Depth Report #50: Urinary incontinence.]

Kidney Stones. Kidney stones can be caused by urinary tract infections (as well as increase the risk for UTIs in the first place). Those known as struvite stones are almost always caused by urinary tract infections due to bacteria that secrete certain enzymes. These enzymes raise urine concentrations of ammonia, which composes the crystals forming struvite stones. The stone-promoting bacterium is usually Proteus , but others include Pseudomonas , Klebsiella , Providencia , Serratia , and staphylococci.

Complications of Urinary Tract Infections in Pregnancy

Urinary tract infections during pregnancy pose particular risks for both mother and child:

• If asymptomatic bacteriuria is not detected and treated promptly in pregnant women, as many as 25% develop kidney infection (pyelonephritis), which in turn increases the risk for premature birth, infant mortality, and later chronic kidney disease.
• Even if kidney infection does not develop, untreated UTIs occurring in the first and third trimester of pregnancy slightly increase the risk for mental retardation and developmental delay in the infant.
• Certain strains of E. coli can increase the risk for complications during pregnancy, including miscarriage or premature delivery, even if pyelonephritis does not develop.
• Infants of women who harbor Ureaplasma urealyticum also have an increased risk for respiratory infections.

Complications in Children with Urinary Tract Infections

Urinary tract infections are a major cause of hospitalization in children. Untreated, they can be very serious, particularly in children under 4 years old. Fortunately, with prompt treatment, childhood cases of upper urinary tract infections rarely cause any serious consequences.

Spread of Infection. Widespread infection is a major complication of a primary infection. Although laboratory tests in some infants with UTI may suggest the presence of meningitis (inflammation of the spinal column), in most of these UTI cases the outcome is good with treatment and there do not appear to be any neurological symptoms afterward.

Kidney Scarring. Kidney scarring is the major concern in children who develop serious or recurrent UTIs. Scarring in young growing kidneys is much more serious than in the mature kidney. Over the years, it increases the risk for hypertension and kidney failure. In one study, evidence of scarring developed in 6% of children who had been hospitalized for a urinary tract infection. Children most at risk for this complication include:

• Children with vesicoureteral reflux (VUR). (Carefully managed vesicoureteral reflux without scarring is not associated with serious complications.)
• Abnormally structured urinary tracts
• Recurrent kidney infections
• A delay in treating an acute UTI

One encouraging study followed children with evidence of kidney scarring for 16 to 26 years. On average, their total kidney function was well preserved, although the scarred kidney had signs of lower function and patients with scarring in both kidneys were at higher risk for future problems. Earlier studies have shown poorer results, which suggests that outcomes are now improving with early detection and better follow-up.

Complications in People with Diabetes

Women with diabetes have more frequent and more severe UTIs than women without the disease. They also are more frequently hospitalized for kidney infections. In fact, the most serious, but rare, complications of urinary tract infections (pyelonephritis, widespread infections, abscesses, inflammation of the bladder wall) occur mostly in patients with diabetes.

• Review Date: 6/16/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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