A Urinary Tract Infection (UTI) is a common bacterial infection affecting the parts of the body responsible for making and passing urine. Most frequently, the infection is confined to the lower urinary tract (the urethra and the bladder), a condition known as cystitis. The typical cause is the bacterium Escherichia coli (E. coli), which originates from the gastrointestinal tract. While some mild UTIs might resolve on their own, most bacterial infections require medical intervention to prevent the bacteria from migrating upward. Ignoring symptoms allows the bacterial load to multiply and ascend, setting the stage for serious complications.
Worsening Lower Tract Discomfort
When a UTI is left untreated, the discomfort in the urethra and bladder intensifies as the bacterial colony grows. The inflammation of the bladder lining (cystitis) leads to a more severe form of dysuria, which is burning or stinging pain during urination. This localized irritation increases the frequency and urgency of urination, often resulting in only small amounts of urine being passed.
The persistent inflammation can also cause pelvic discomfort or a feeling of pressure in the lower abdomen. In advanced cases, the bacteria can damage the tissue, leading to hematuria (visible blood in the urine). The urine may also appear cloudy or have a strong, foul odor due to the concentration of bacteria and white blood cells.
When Infection Reaches the Kidneys
The most significant progression of an untreated UTI occurs when bacteria travel from the bladder up the ureters and into the kidneys, a condition called pyelonephritis. This upper tract infection is far more serious than cystitis because it directly affects the body’s primary blood-filtering organs. Once in the kidneys, the infection causes distinct and severe systemic symptoms that signal a medical emergency.
Patients with pyelonephritis often experience a high fever, shaking chills, and intense pain in the flank or back, typically felt just under the ribs. The systemic nature of the infection frequently triggers nausea and vomiting, which can lead to rapid dehydration.
This severe kidney infection requires immediate medical attention, often necessitating hospitalization for intravenous (IV) antibiotics to control the overwhelming bacterial load. Prolonged or recurrent pyelonephritis carries the risk of causing permanent damage to the nephron structures within the kidney. This scarring can impair the kidney’s long-term function and increase the risk of chronic kidney disease.
The Danger of Systemic Spread
The most life-threatening complication of an untreated UTI is urosepsis, which develops when the bacterial infection from the kidneys enters the bloodstream. Sepsis is the body’s overwhelming and dysfunctional response to the infection, which begins to injure its own tissues and organs. The urinary tract is a common source, accounting for a significant percentage of all sepsis cases.
Once the bacteria are circulating in the blood, the systemic inflammatory response is triggered, leading to signs of severe illness. These include dangerously low blood pressure, a rapid heart rate, and an increased respiratory rate as the body struggles to compensate. In older adults or those with underlying health conditions, an altered mental status, such as confusion or disorientation, can be an early sign of systemic infection.
If the body’s response is not quickly managed, sepsis can progress to septic shock. This is characterized by a profound drop in blood pressure that requires medication to maintain. This state starves the body’s tissues of oxygen and can rapidly lead to multi-organ failure, affecting the lungs, heart, and brain. Even with aggressive treatment in an intensive care unit (ICU), the mortality rate for septic shock is estimated to be around 40%.