Urinary Tract Infections (UTIs)


A urinary tract infection (also known as a bladder infection or acute cystitis) is the infection of a part or parts of the urinary tract, which is made up of the kidneys, ureters, bladder, and urethra. A urinary tract infection (UTI) is not technically a sexually transmitted infection, however, sexual activity is a common cause of UTIs for sexually active adults. 1 When the infection affects the lower urinary tract, the condition is known as simple cystitis (a bladder infection), and when it affects the upper urinary tract, it is known as pyelonephritis (a kidney infection). The most common causal agent of UTIs is the bacterium Escherichia coli, commonly found in the lower intestine of warm-blooded organisms.1


Signs or symptoms of a urinary tract infection may not always be noticeable, but if symptoms are present, they will typically manifest in one of the following ways:

  • A strong, persistent urge to urinate
  • A burning sensation when urinating
  • Frequent, small amounts of urine
  • Urine that appears cloudy
  • Urine that appears red, bright pink, or cola-colored — a sign of blood in the urine
  • Strong-smelling urine
  • Pelvic pain (in women)
  • Rectal pain (in men)2

UTI symptoms may also vary depending on which part of the urinary tract is infected.2 If only the urethra (the tube that leads from the bladder and transports and discharges urine outside the body) is infected, burning with urination should be the only symptom noticed. Infection of the urethra is known as urethritis.

If the infection is in the bladder, the infection is called cystitis and may include the following symptoms:

  • Pelvic pressure
  • Lower abdominal discomfort
  • Frequent, painful urination
  • Blood or pus in the urine2

Most UTIs involve only the bladder and urethra, known as the lower urinary system. However, serious infections may spread to the upper urinary system (the kidneys and ureters), resulting in an infection known as acute pyelonephritis. Acute pyelonephritis is a very serious medical condition, in which the infection has the opportunity to enter the bloodstream (sepsis) and spread to other healthy tissues in the body.2

A person in tan undergarments laying on a bed. Their hands are over their abdomen.

If such blood infection occurs, one’s risk of death increases significantly, particularly among children and the elderly. The presentation of acute pyelonephritis is notably distinct from that of the less severe lower tract infections, and typically include the following symptoms:

  • Upper back and side (flank) pain
  • High fever
  • Shaking and chills
  • Nausea
  • Vomiting
  • Frequent urge to urinate
  • Generalized malaise
  • Abdominal pain2

Signs and symptoms of a urinary tract infection may be especially difficult to observe in children or the elderly. In young children, the only symptom of a urinary tract infection may be a fever. Infants may also feed poorly, vomit, sleep excessively, or show signs of jaundice (yellowing of the skin and eyes). In older children, a loss of bladder control can occur. UTI symptoms in the elderly can be even more vague, sometimes presenting as a loss of bladder control, a change in mental status, or general fatigue. Diagnosis of UTIs in the elderly can be further complicated by preexisting or comorbid incontinence or dementia.1

Causes and Risk Factors

Urinary tract infections normally occur when bacteria enter the urinary tract through the urethra and begin to multiply in the bladder, sometimes spreading to other nearby tissues. Although the human urinary system is designed to keep out such microscopic invaders, these defenses are not perfect and sometimes fail. When this occurs, bacteria may seize this opportunity to secure habitat and grow into a full-blown infection in the urinary tract. Infection may also occur via the blood or lymph. The common intestinal bacterium, E. coli, causes 80-85% of urinary tract infections. After gaining entry to the bladder, E. coli are able to attach to the bladder wall and form a biofilm that resists the body’s immune response. However, other bacteria, such as Staphylococcus saprophyticus (responsible for 5-15% of cases) or viruses and fungi, can also cause UTIs. Risk factors for contracting a UTI include the following circumstances:2

Three pairs of underwear hung on a clothesline hanger outdoors.
  • Having a Vagina. UTIs are more common in people with vaginas than people with penises, and many people with vaginas experience more than one infection throughout their life. This is likely due to the fact that the urethra is shorter in the vaginal reproductive system than the penis, making it easier for bacteria to enter.
  • Being sexually active. For individuals who engage in penile-vaginal intercourse, the repeated motion of a penis entering a vagina can cause bacteria to shift from other areas and enter the urethra. This is especially true if you alternate from anal to vaginal sex, where bacteria from the anal cavity an easily be transferred. If you transition from anal to vaginal penetration, be sure to change condoms to prevent the spread of bacteria.
  • Using certain types of birth control. Research has shown that people who use diaphragms as a method of birth control may be at higher risk for contracting a UTI, as well as females who use spermicidal agents.2
  • Onset of menopause. During menopause, UTIs may become more common due to a lack of estrogen, which causes changes in the urinary tract that make it more vulnerable to infection.
  • Having urinary tract abnormalities. Infants born with urinary tract abnormalities that do not allow urine to normally exit the body or cause urine to back up in the urethra have an increased risk of contracting a UTI.
  • Having blockages in the urinary tract. Kidney stones or an enlarged prostate can trap urine in the bladder and increase the risk of contracting a UTI.
  • Having a suppressed immune system. Diabetes and other diseases that impair the immune system can increase the risk of contracting a UTI.
  • Using a catheter to urinate. People who are unable to urinate on their own and use a tube (catheter) to urinate have an increased risk of UTIs. This may include people who are hospitalized, people with neurological problems that make it difficult to control their ability to urinate, and people who are paralyzed.


UTIs are easily diagnosable. A physician may utilize a variety of tests and procedures to diagnose a UTI. These tests may include the following:

  • Urine analysis. Your doctor may ask for a urine sample for lab analysis to look for white blood cells, red blood cells, or bacteria. To avoid potential contamination of the sample, you may be instructed to wipe your genital area with an antiseptic pad and collect the urine midstream.
  • Urine culture. Lab analysis of the urine is sometimes followed by a urine culture: a test that uses your urine sample to grow bacteria in a lab. This test tells your doctor which bacteria are causing your infection and which medications will be most effective for treatment.
  • Urinary Tract Imaging. If your doctor suspects that an abnormality in your urinary tract causes frequent infections, you may be asked to complete an ultrasound or a computerized tomography (CT) scan to create images of your urinary tract. In certain situations, your doctor may also use a contrast dye to highlight certain structures in your urinary tract. Another test called an intravenous pyelogram (IVP), uses X-rays with contrast dye to create images. Historically, doctors used this test for urinary tract imaging, but it is being replaced by ultrasounds or CT scans.
  • Cystoscopy. If you have recurrent UTIs, your doctor may perform a cystoscopy using a long, thin tube with a lens (cystoscope) to see inside of your urethra and bladder. The cystoscope is inserted into your urethra and passed through to your bladder.

While UTI symptoms are already sometimes vague, a diagnostic physician must not only diagnosis the infection but also differentiate this vague condition from a huge variety of other similarly vague conditions. Individuals with an inflamed vagina (a condition easily confused as a symptom of a UTI) may actually be experiencing a yeast infection. Because yeast is a fungus rather than a bacterium, the methods of treating this kind of infection typically differ from those used for UTIs. Inflammation of the prostate may also be considered in the physician’s differential diagnosis.


Most urinary tract infections can be treated successfully without complication. Bladder infection (cystitis) symptoms typically dissipate within a few days after treatment begins. Kidney infections (acute pyelonephritis) are generally longer lasting, sometimes taking one week or longer for symptoms to disappear once treatment has begun.2.


When given proper and prompt treatment, lower urinary tract infections rarely lead to other health complications. However, if left untreated, such infections could progress to trigger a number of potentially life-threatening conditions. Typically, an untreated lower urinary tract infection will eventually spread from the bladder to one or both kidneys, possibly causing irreversible damage to proper kidney function and increasing one’s risk of complete kidney failure. There is also a small chance that the infection may enter the bloodstream from the kidneys, resulting in a possibly fatal whole-body inflammation known as sepsis. Recurrent infections are a common complication, especially in women who have experienced three or more UTIs.4 It is due to these serious complications that individuals observing early UTI-like symptoms are highly encouraged to seek immediate medical help.1

It is also possible to develop a secondary infection as a side effect of the antibiotics used to treat urinary tract infections. People with vaginas may find that they developed a yeast infection or bacterial vaginosis upon completing their prescribed round of antibiotics. This is because antibiotics can alter the normal “good” bacteria that reside inside the vagina. If this does occur, it is important to follow up with a physician who can provide a proper course of action.5


Multiple white pills against a pink background.

The standard treatment for urinary tract infections is the prescription of oral antibiotics taken over a typical course of seven to ten days. A physician may also prescribe a pain medication to numb the bladder and urethra in order to relieve burning during urination. Such urinary-tract analgesics tend to cause urine to turn red or orange in color.2


Patients with frequent UTIs should seek specialized medical help. While there are many at-home recommendations and remedies online that promote the prevention of UTIs, many have not been proven to be effective. The most popular at-home method to treat UTIs is to drink cranberry juice or eat cranberries. However, research on this method is inconclusive and while this may provide temporary relief, cranberries can not cure an infection.5

The following are techniques that have been proven to promote healthier vaginal hygiene, which decreases the risk of spreading bacteria:

A pair of hands holding a thong.
  • Wipe from front to back. This prevents the potential spread of fecal matter to the urethra.
  • Do not sleep in Thong underwear. Similar to wiping incorrectly, thongs can transfer bacteria. For people who regularly get UTIs, switching to cotton underwear in a different silhouette may help.
  • Urinate after intercourse. This helps to flush out any bacteria that may have shifted during intercourse.
  • Avoid feminine cleaning products. Using feminine body washes or “douching” can disrupt the natural pH of the vagina, which can eliminate good bacteria and leave more room for bad bacteria.1

Other prevention techniques include using sanitary pads instead of tampons, taking showers instead of baths, changing dietary practices, drinking healthy fluids, and avoiding tight-fitting pants.

It is important to note that these techniques have not been proven to be effective and should not be used in place of going to a doctor. For patients who still experience frequent, recurring infections, a physician may make specific treatment recommendations, such a single dose of an antibiotic to be taken after sexual intercourse.2

Concluding Remarks

Urinary tract infections are both common and curable. While they may be painful, they are usually not very serious if treated properly and quickly. At the first feeling of discomfort, it is best to schedule an appointment with a doctor immediately. Be sure to always complete your full round of antibiotics and abstain from sexual activity until the full round of antibiotics has been completed and symptoms have fully dissipated. Lastly, for individuals with vaginas, remember to always urinate after intercourse.


  1. “Uncomplicated Urinary Tract Infection in Adults Including Uncomplicated Pyelonephritis.”Urology Clinics of North America. 2009. p.1-12. Date Accessed: 20 Jan. 2020.
  2. “Urinary Tract Infection (UTI).” Mayo Clinic. Mayo Foundation for Medical Education and Research. n.d. Date Accessed: 20 Jan. 2020.
  3. “Dialysis: MedlinePlus.”U.S National Library of Medicine. U.S. National Library of Medicine. n.d. Date Accessed: 20 Jan. 2020.
  4. “Urinary Tract Infection – Adults: MedlinePlus Medical Encyclopedia.”U.S National Library of Medicine. U.S. National Library of Medicine, n.d. Date Accessed: 20 Jan. 2020.
  5. “Urinary Tract Infection in Women.”University of Maryland Medical Center. n.d. Date Accessed: 20 Jan. 2020.

Last updated: 5 March 2020.