URINARY TRACT INFECTION (UTI)
When the bladder empties, a muscle called the sphincter relaxes and urine flows out of the body through the urethra. The opening of the urethra is at the end of the penis in males and in front of the vagina in females.
The urinary tract has several systems to prevent infection. The points where the ureters attach to the bladder act like one-way valves to prevent urine from backing up toward the kidneys, and urination washes microbes out of the body. In men, the prostate gland produces secretions that slow bacterial growth. In both sexes, immune defenses also prevent infection. But despite these safeguards, infections still occur. Certain bacteria have a strong ability to attach themselves to the lining of the urinary tract.
Sexual activity can move microbes from the bowel or vaginal cavity to the urethral opening. If these microbes have special characteristics that allow them to live in the urinary tract, it is harder for the body to remove them quickly enough to prevent infection. Following sexual intercourse, most women have a significant number of bacteria in their urine, but the body normally clears them within 24 hours.
However, some forms of birth control increase the risk of UTI. In some women, certain spermicides may irritate the skin, increasing the risk of bacteria invading surrounding tissues. Using a diaphragm may slow urinary flow and allow bacteria to multiply. Condom use is also associated with increased risk of UTIs, possibly because of the increased trauma that occurs to the vagina during sexual activity. Using spermicides with diaphragms and condoms can increase risk even further.
Another common source of infection is catheters, or tubes, placed in the urethra and bladder. Catheters interfere with the body’s ability to clear microbes from the urinary tract. Bacteria travel through or around the catheter and establish a place where they can thrive within the bladder. A person who cannot urinate in the normal way or who is unconscious or critically ill often needs a catheter for more than a few days. The Infectious Diseases Society of America recommends using catheters for the shortest time possible to reduce the risk of a UTI.3
Many women suffer from frequent UTIs. About 20 percent of young women with a first UTI will have a recurrent infection.4 With each UTI, the risk that a woman will continue having recurrent UTIs increases.5 Some women have three or more UTIs a year. However, very few women will have frequent infections throughout their lives. More typically, a woman will have a period of 1 or 2 years with frequent infections, after which recurring infections cease.
Men are less likely than women to have a first UTI. But once a man has a UTI, he is likely to have another because bacteria can hide deep inside prostate tissue. Anyone who has diabetes or a problem that makes it hard to urinate may have repeat infections.
Research funded by the National Institutes of Health (NIH) suggests that one factor behind recurrent UTIs may be the ability of bacteria to attach to cells lining the urinary tract. One NIH-funded study found that bacteria formed a protective film on the inner lining of the bladder in mice.6 If a similar process can be demonstrated in humans, the discovery may lead to new treatments to prevent recurrent UTIs. Another line of research has indicated that women who are “nonsecretors” of certain blood group antigens may be more prone to recurrent UTIs because the cells lining the vagina and urethra may allow bacteria to attach more easily. A nonsecretor is a person with an A, B, or AB blood type who does not secrete the normal antigens for that blood type in bodily fluids, such as fluids that line the bladder wall.7
To find out whether a person has a UTI, the health care provider will ask about urinary symptoms and then test a sample of urine for the presence of bacteria and white blood cells, which are produced by the body to fight infection. Because bacteria can be found in the urine of healthy individuals, a UTI is diagnosed based both on symptoms and a laboratory test. The person will be asked to give a “clean catch” urine sample by washing the genital area and collecting a “midstream” sample of urine in a sterile container. This method of collecting urine helps prevent bacteria around the genital area from getting into the sample and confusing the test results. Usually, the sample is sent to a laboratory, although some health care providers’ offices are equipped to do the testing. For people with recurring infections and patients in the hospital, the urine may be cultured. The culture is performed by placing part of the urine sample in a tube or dish with a substance that encourages any bacteria present to grow. Once the bacteria have multiplied, which usually takes 1 to 3 days, they can be identified. The health care provider may also order a sensitivity test, which tests the bacteria for sensitivity to different antibiotics to see which medication is best for treating the infection.
If a person has recurrent UTIs, the health care provider may order some additional tests to determine if the person’s urinary tract is normal.
Kidney and bladder ultrasound. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. The procedure is performed in a health care provider’s office, outpatient center, or hospital by a specially trained technician, and the images are interpreted by a radiologist—a doctor who specializes in medical imaging; anesthesia is not needed. The images can show abnormalities in the kidneys and bladder. However, this test cannot reveal all important urinary abnormalities or measure how well the kidneys work.
Voiding cystourethrogram. This test is an x-ray image of the bladder and urethra taken while the bladder is full and during urination, also called voiding. As the person lies on the x-ray table, a health care provider inserts the tip of a thin, flexible tube called a catheter through the urethra into the bladder. The bladder and urethra are filled with a special dye called contrast medium, to make the structures clearly visible on the x-ray images. The x rays are taken from various angles while the bladder is full of contrast medium. The catheter is then removed and x-ray images are taken during urination. The procedure is performed in a health care provider’s office, outpatient center, or hospital by an x-ray technician. The technician is supervised by a radiologist while the images are taken. The radiologist then interprets the images. Anesthesia is not needed, but light sedation may be used for some people. This test can show abnormalities of the inside of the urethra and bladder. The test can also determine whether the flow of urine is normal when the bladder empties.
Computerized tomography (CT) scan. CT scans use a combination of x rays and computer technology to create three-dimensional (3-D) images. A CT scan may include the injection of contrast medium. CT scans require the person to lie on a table that slides into a tunnel-shaped device where the x rays are taken. The procedure is performed in an outpatient center or hospital by an x-ray technician, and the images are interpreted by a radiologist; anesthesia is not needed. CT scans can provide clearer, more detailed images to help the health care provider understand the problem.
Magnetic resonance imaging (MRI). MRI machines use radio waves and magnets to produce detailed pictures of the body’s internal organs and soft tissues without using x rays. An MRI may include an injection of contrast medium. With most MRI machines, the person lies on a table that slides into a tunnel-shaped device that may be open ended or closed at one end; some newer machines are designed to allow the person to lie in a more open space. The procedure is performed in an outpatient center or hospital by a specially trained technician, and the images are interpreted by a radiologist; anesthesia is not needed though light sedation may be used for people with a fear of confined spaces. Like CT scans, MRIs can provide clearer, more detailed images.
Radionuclide scan. A radionuclide scan is an imaging technique that relies on the detection of small amounts of radiation after injection of radioactive chemicals. Because the dose of the radioactive chemicals is small, the risk of causing damage to cells is low. Special cameras and computers are used to create images of the radioactive chemicals as they pass through the kidneys. Radionuclide scans are performed in a health care provider’s office, outpatient center, or hospital by a specially trained technician, and the images are interpreted by a radiologist; anesthesia is not needed. Radioactive chemicals injected into the blood can provide information about kidney function. Radioactive chemicals can also be put into the fluids used to fill the bladder and urethra for x ray, MRI, and CT imaging.
Urodynamics. Urodynamic testing is any procedure that looks at how well the bladder, sphincters, and urethra are storing and releasing urine. Most of these tests are performed in the office of a urologist—a doctor who specializes in urinary problems—by a urologist, physician assistant, or nurse practitioner. Some procedures may require light sedation to keep a person calm. Most urodynamic tests focus on the bladder’s ability to hold urine and empty steadily and completely. Urodynamic tests can also show whether the bladder is having abnormal contractions that cause leakage. A health care provider may order these tests if there is evidence that the person has some kind of nerve damage.
Cystoscopy. Cystoscopy is a procedure that uses a tubelike instrument to look inside the urethra and bladder. Cystoscopy is performed by a doctor in a health care provider’s office, outpatient facility, or hospital with local anesthesia. However, in some cases, sedation and regional or general anesthesia are needed. Cystoscopy may be used to look for swelling, redness, and other signs of infection.
Most UTIs are caused by bacteria, which are treated with bacteria-fighting medications called antibiotics or antimicrobials. The choice of medication and length of treatment depend on the patient’s history and the type of bacteria causing the infection. Some antibiotics may be ruled out if a person has allergies to them. The sensitivity test takes 48 hours to complete and is especially useful in helping the health care provider select the antibiotic most likely to be effective in treating an infection. Longer treatment may be needed if the first antibiotic given is not effective.
When a UTI occurs in a healthy person with a normal, unobstructed urinary tract, the term uncomplicated is used to describe the infection. Most young women who have UTIs have uncomplicated UTIs, which can be cured with 2 or 3 days of treatment. Single-dose treatment is less effective. Longer treatment causes more side effects and is not more effective. A follow-up urinalysis helps to confirm the urinary tract is infection-free. Taking the full course of treatment is important because symptoms may disappear before the infection is fully cleared.
Complicated UTIs occur when a person—for example, a pregnant woman or a transplant patient—is weakened by another condition. A UTI is also complicated when the person has a structural or functional abnormality of the urinary tract, such as an obstructive kidney stone or prostate enlargement that squeezes the urethra. Health care providers should assume that men and boys have a complicated UTI until proven otherwise.
Severely ill patients with kidney infections may be hospitalized until they can take fluids and needed medications on their own. Kidney infections may require several weeks of antibiotic treatment. Kidney infections in adults rarely lead to kidney damage or kidney failure unless they go untreated or are associated with urinary tract obstruction.
Bladder infections are generally self-limiting, but antibiotic treatment significantly shortens the duration of symptoms. People usually feel better within a day or two of treatment. Symptoms of kidney and prostate infections last longer. Drinking lots of fluids and urinating frequently will speed healing. If needed, various medications are available to relieve the pain of a UTI. A heating pad on the back or abdomen may also help.
Recurrent Infections in Women
Health care providers may advise women who have recurrent UTIs to try one of the following treatment options:
- Take low doses of the prescribed antibiotic daily for 6 months or longer. If taken at bedtime, the medication remains in the bladder longer and may be more effective. NIH-supported research has shown this therapy to be effective without causing serious side effects.
- Take a single dose of an antibiotic after sexual intercourse.
- Take a short course—2 or 3 days—of an antibiotic when symptoms appear.
To try to prevent an infection, health care providers may suggest women
- Drink plenty of water every day
- Urinate when the need arises and avoid resisting the urge to urinate
- Urinate after sexual intercourse
- Switch to a different method of birth control if recurring UTIs are a problem
Infections during Pregnancy
During pregnancy, bacterial infection of the urine—even in the absence of symptoms—can pose risks to both the mother and the baby. Some antibiotics are not safe to take during pregnancy. In selecting the best treatments, health care providers consider various factors such as the medication’s effectiveness, the stage of pregnancy, the mother’s health, and potential effects on the fetus.
Curing infections that stem from a urinary obstruction or other systemic disorder depends on finding and correcting the underlying problem, sometimes with surgery. If the root cause goes untreated, this group of patients is at risk for kidney damage. Also, such infections tend to arise from a wider range of bacteria and sometimes from more than one type of bacteria at a time.
Infections in Men
Urinary tract infections in men are often the result of an obstruction—for example, a urinary stone or enlarged prostate—or are from a catheter used during a medical procedure. The first step in treating such an infection is to identify the infecting organism and the medications to which it is sensitive.
Prostate infections—chronic bacterial prostatitis—are harder to cure because antibiotics may be unable to penetrate infected prostate tissue effectively. For this reason, men with bacterial prostatitis often need long-term treatment with a carefully selected antibiotic. UTIs in men are frequently associated with acute bacterial prostatitis, which can be life threatening if not treated urgently.
Changing some daily habits may help a person prevent recurrent UTIs.
Eating, Diet, and Nutrition
Drinking lots of fluid can help flush bacteria from the system. Water is best. Most people should try for six to eight, 8-ounce glasses a day. Talk with your health care provider if you can’t drink the recommended amount due to other health problems, such as urinary incontinence, urinary frequency, or kidney failure.
A person should urinate often and when the urge arises. Bacteria can grow when urine stays in the bladder too long. Women and men should urinate shortly after sex to flush away bacteria that might have entered the urethra during sex. Drinking a glass of water will also help flush bacteria away.
After using the toilet, women should wipe from front to back. This step is most important after a bowel movement to keep bacteria from getting into the urethra.
Cotton underwear and loose-fitting clothes should be worn, so air can keep the area around the urethra dry. Tight-fitting jeans and nylon underwear should be avoided because they can trap moisture and help bacteria grow.
For women, using a diaphragm or spermicide for birth control can lead to UTIs by increasing bacteria growth. A woman who has trouble with UTIs should try switching to a new form of birth control. Unlubricated condoms or spermicidal condoms increase irritation, which may help bacteria grow. Switching to lubricated condoms without spermicide or using a nonspermicidal lubricant may help prevent UTIs.
PROSTATE SPECIFIC ANTIGEN (PSA)
Prostate-specific antigen, or PSA, is a protein produced by cells of the prostate gland. The PSA test measures the level of PSA in a man’s blood. For this test, a blood sample is sent to a laboratory for analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.
The blood level of PSA is often elevated in men with prostate cancer, and the PSA test was originally approved by the FDA in 1986 to monitor the progression of prostate cancer in men who had already been diagnosed with the disease. In 1994, the FDA approved the use of the PSA test in conjunction with a digital rectal exam (DRE) to test asymptomatic men for prostate cancer. Men who report prostate symptoms often undergo PSA testing (along with a DRE) to help doctors determine the nature of the problem.
In addition to prostate cancer, a number of benign (not cancerous) conditions can cause a man’s PSA level to rise. The most frequent benign prostate conditions that cause an elevation in PSA level are prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There is no evidence that prostatitis or BPH leads to prostate cancer, but it is possible for a man to have one or both of these conditions and to develop prostate cancer as well.
Until recently, many doctors and professional organizations encouraged yearly PSA screening for men beginning at age 50. Some organizations recommended that men who are at higher risk of prostate cancer, including African American men and men whose father or brother had prostate cancer, begin screening at age 40 or 45. However, as more has been learned about both the benefits and harms of prostate cancer screening, a number of organizations have begun to caution against routine population screening. Although some organizations continue to recommend PSA screening, there is widespread agreement that any man who is considering getting tested should first be informed in detail about the potential harms and benefits.
Currently, Medicare provides coverage for an annual PSA test for all Medicare-eligible men age 50 and older. Many private insurers cover PSA screening as well.
There is no specific normal or abnormal level of PSA in the blood. In the past, most doctors considered PSA levels of 4.0 ng/mL and lower as normal. Therefore, if a man had a PSA level above 4.0 ng/mL, doctors would often recommend a prostate biopsy to determine whether prostate cancer was present.
However, more recent studies have shown that some men with PSA levels below 4.0 ng/mL have prostate cancer and that many men with higher levels do not have prostate cancer (1). In addition, various factors can cause a man’s PSA level to fluctuate. For example, a man’s PSA level often rises if he has prostatitis or a urinary tract infection. Prostate biopsies and prostate surgery also increase PSA level. Conversely, some drugs—including finasteride and dutasteride, which are used to treat BPH—lower a man’s PSA level. PSA level may also vary somewhat across testing laboratories.
Another complicating factor is that studies to establish the normal range of PSA levels have been conducted primarily in populations of white men. Although expert opinions vary, there is no clear consensus regarding the optimal PSA threshold for recommending a prostate biopsy for men of any racial or ethnic group.
In general, however, the higher a man’s PSA level, the more likely it is that he has prostate cancer. Moreover, continuous rise in a man’s PSA level over time may also be a sign of prostate cancer.
If a man who has no symptoms of prostate cancer chooses to undergo prostate cancer screening and is found to have an elevated PSA level, the doctor may recommend another PSA test to confirm the original finding. If the PSA level is still high, the doctor may recommend that the man continue with PSA tests and DREs at regular intervals to watch for any changes over time.
If a man’s PSA level continues to rise or if a suspicious lump is detected during a DRE, the doctor may recommend additional tests to determine the nature of the problem. A urine test may be recommended to check for a urinary tract infection. The doctor may also recommend imaging tests, such as a transrectal ultrasound, x-rays, or cystoscopy.
If prostate cancer is suspected, the doctor will recommend a prostate biopsy. During this procedure, multiple samples of prostate tissue are collected by inserting hollow needles into the prostate and then withdrawing them. Most often, the needles are inserted through the wall of the rectum (transrectal biopsy); however, the needles may also be inserted through the skin between the scrotum and the anus (transperineal biopsy). A pathologist then examines the collected tissue under a microscope. The doctor may use ultrasound to view the prostate during the biopsy, but ultrasound cannot be used alone to diagnose prostate cancer.
Hematuria is blood in the urine. Two types of blood in the urine exist. Blood that can be seen in the urine is called gross hematuria. Blood that cannot be seen in the urine, except when examined with a microscope, is called microscopic hematuria.
The urinary tract. Drawing of the urinary tract in the outline of a male figure.
Most people with microscopic hematuria do not have symptoms. People with gross hematuria have urine that is pink, red, or cola-colored due to the presence of red blood cells (RBCs). Even a small amount of blood in the urine can cause urine to change color. In most cases, people with gross hematuria do not have other symptoms. However, people with gross hematuria that includes blood clots in the urine may have pain.
Hematuria can be caused by menstruation, vigorous exercise, sexual activity, viral illness, trauma, or infection, such as a urinary tract infection (UTI). More serious causes of hematuria include:
- Cancer of the kidney or bladder
- Inflammation of the kidney, urethra, bladder, or prostate—a walnut-shaped gland in men that surrounds the urethra at the neck of the bladder and supplies fluid that goes into semen
- Polycystic kidney disease—an inherited disorder characterized by many grape-like clusters of fluid-filled cysts that make both kidneys larger over time, taking over and destroying working kidney tissue
- Blood clots
- Blood clotting disorders, such as hemophilia
- Sickle cell disease—an inherited disorder in which RBCs form an abnormal crescent shape, resulting in less oxygen delivered to the body’s tissues, clogging of small blood vessels, and disruption of healthy blood flow
Almost anyone, including children and teens, can have hematuria. Factors that increase the chance a person will have hematuria include:
- A family history of kidney disease
- An enlarged prostate, which typically occurs in men age 50 or older
- Urinary stone disease
- Certain medications including aspirin and other pain relievers, blood thinners, and antibiotics
- Strenuous exercise such as long-distance running
- A recent bacterial or viral infection
Hematuria is diagnosed with urinalysis, which is testing of a urine sample. The urine sample is collected in a special container in a health care provider’s office or commercial facility and can be tested in the same location or sent to a lab for analysis. For the test, a nurse or technician places a strip of chemically treated paper, called a dipstick, into the urine. Patches on the dipstick change color when RBCs are present in urine. When blood is visible in the urine or a dipstick test of the urine indicates the presence of RBCs, a health care provider examines the urine with a microscope to make an initial diagnosis of hematuria. The next step is to diagnose the cause of the hematuria.
The health care provider will take a thorough medical history. If the history suggests a cause that does not require treatment, the urine should be tested again after 48 hours for the presence of RBCs. If two of three urine samples show too many RBCs when viewed with a microscope, more serious causes should be explored. The health care provider may order one or more of the following tests:
Urinalysis. Further testing of the urine may be done to check for problems that can cause hematuria, such as infection, kidney disease, and cancer. The presence of white blood cells signals a UTI. RBCs that are misshapen or clumped together to form little tubes, called casts, may indicate kidney disease. Large amounts of protein in the urine, called proteinuria, may also indicate kidney disease. The urine can also be tested for the presence of cancer cells.
Blood test. A blood test involves drawing blood at a health care provider’s office or commercial facility and sending the sample to a lab for analysis. A blood test can show the presence of high levels of creatinine, a waste product of normal muscle breakdown, which may indicate kidney disease.
Biopsy. A biopsy is a procedure that involves taking a piece of kidney tissue for examination with a microscope. The biopsyis performed by a health care provider in a hospital with light sedation and local anesthetic. The health care provider uses imaging techniques such as ultrasound or a computerized tomography (CT) scan to guide the biopsy needle into the kidney. The kidney tissue is examined in a lab by a pathologist—a doctor who specializes in diagnosing diseases. The test helps diagnose the type of kidney disease causing hematuria.
Cystoscopy. Cystoscopy is a procedure that uses a tubelike instrument to look inside the urethra and bladder. Cystoscopy is performed by a health care provider in the office, an outpatient facility, or a hospital with local anesthesia. However, in some cases, sedation and regional or general anesthesia are needed. Cystoscopy may be used to look for cancer cells in the bladder, particularly if cancer cells are found with urinalysis. More information is provided in the NIDDK health topic, Cystoscopy and Ureteroscopy.
Kidney imaging tests. Intravenous pyelogram (IVP) is an x ray of the urinary tract. A special dye, called contrast medium, is injected into a vein in the person’s arm, travels through the body to the kidneys, and makes urine visible on the x ray. The contrast medium also shows any blockage in the urinary tract. When a small mass is found with IVP, another imaging test, such as an ultrasound, CT scan, or magnetic resonance imaging (MRI), can be used to further study the mass. Imaging tests are performed in an outpatient center or hospital by a specially trained technician, and the images are interpreted by a radiologist—a doctor who specializes in medical imaging. Anesthesia is not needed, though light sedation may be used in some cases. Imaging tests may show a tumor, a kidney or bladder stone, an enlarged prostate, or other blockage of the normal flow of urine. More information is provided in the NIDDK health topic, Imaging of the Urinary Tract.
Source: National Institute of Diabetes and Digestive and Kidney Diseases (April 2012)