Diseases of the Urinogenital System - Infection in the urinary tract

Infection in the urinary tract is a common disorder that can be serious if the kidneys themselves are involved.


Infection of the bladder is called cystitis . The symptoms include a burning sensation when urine is passed, the frequent need to urinate, occasionally blood in the urine, and sometimes difficulty in starting to urinate. Cystitis is rarely accompanied by high fever.

The problem may be recurrent and is more usual with women than men, probably because the female urethra is shorter and closer to the rectum, permitting bacteria to enter the bladder more easily. These bacteria multiply in the urine contained in the bladder, causing irritation to the bladder walls and producing the symptoms described above.

Cystitis should be treated promptly because the infection in the bladder can easily spread to the kidneys, with serious consequences. Treatment usually consists of antibiotics after urine analysis and culture have determined the type of bacteria causing the infection. Cystitis and other kidney infections are especially common during pregnancy because of the body changes that occur at this time. Cystitis can be serious and must be diagnosed and treated promptly to avoid complications.

Other Causes of Infection

Infection of the bladder and kidneys may occur because of poor hygiene in the area of the urethra, especially in women. It is also caused by some congenital defects in the urinary tract or by the insertion of instruments used to diagnose a urinary problem. Sometimes bacteria in the bloodstream can settle in and infect the kidneys. Patients with diabetes seem to be more prone to urinary infections—indeed to infections generally—than other people. Any obstruction to the flow of urine in the urinary tract, such as a kidney stone, increases the possibility of infection in the area behind the obstruction. Damage to the nerves controlling the bladder is another condition that increases the chances of infection in that area.


Infection in the kidneys is called pyelonephritis . Although it sometimes occurs without any symptoms, a first attack usually causes an aching pain in the lower back, probably due to the swelling of the kidneys, as well as nausea, vomiting, diarrhea, and sometimes severe pain in the front of the abdomen on one or both sides, depending on whether one or both kidneys are involved. Fever may be quite high, ranging from 103° F to 105° F, often accompanied by chills.

Although the symptoms of pyelonephritis may disappear in a few days without treatment, bacterial destruction of the kidney tissue may be going on. This silent type of infection may eventually disrupt normal kidney function and result in a chronic form of the disease, which in turn can lead to uremia. If the disease is not halted before this, it can be fatal.

Anyone with symptoms of acute pyelonephritis must have prompt medical attention. To diagnose the disease properly, the urine is analyzed and the number and type of bacteria in the urine are determined. The disease is brought under control by the right antibiotics and by administering large amounts of fluids to flush out the kidneys and urinary tract, thus decreasing the number of bacteria in the urine. In its chronic form the disease is much more difficult to cure because bacteria that are lodged deep in the kidney tissue do not seem to be susceptible to antibiotics and are therefore almost impossible to get rid of.

Kidney Stones

Another cause of infection in the bladder and kidneys is obstruction in the urinary tract by kidney stones . These stones, crystallizations of salts that form in the kidney tissue, may be quite small, but they can grow large enough to occupy a considerable part of one or both of the kidneys. The smaller ones often pass from the kidney through the ureters to the bladder, from which they are voided through the urethra. However, obstruction of the flow of urine behind a kidney stone anywhere in the urinary tract usually leads to infection in the urine. This type of infection may lead to attacks of acute pyelonephritis.

Removal of Stones

Kidney stones must be removed unless they cause no symptoms of infection. Removal may be accomplished by flushing out the urinary tract with large fluid intake, by surgical methods, or by lithotripsy, a method of dissolving the stones with electrical shock waves so that the fragments can be flushed out of the body. Any accompanying infection may be treated with antibiotics. A drug, potassium citrate , may also be used to keep kidney stones from forming. See “Urinary Stones” in Ch. 20, Surgery .

Kidney Stones

Why kidney stones form in some people and not in others is not clearly understood. Because of metabolic disorders, certain substances may build up in the body. The increased excretion of these substances in the urine as well as excessive amounts of calcium in the blood may encourage kidney stone formation. People who have gout are also likely to develop them.

Renal Colic

Sometimes the formation and passage of stones cause no symptoms. However, when symptoms do occur with the passage of a kidney stone, they can be uncomfortably severe. The pain that results from the passage of a stone through the ureter, referred to as renal colic , is usually like an intense cramp. It begins in the side or back and moves toward the lower abdomen, the genital region, and the inner thigh on the affected side. The attack may last for a few minutes or for several hours. Sometimes bloody urine may be passed accompanied by a burning sensation.

Kidney stones are more likely to form in middle-aged and older people than in young ones. A history of stones is sometimes found in several generations of a family, since the metabolic disorders encouraging their formation have a hereditary basis.

Treatment for an acute attack of renal colic usually relieves the pain several hours after the patient has taken medication and fluids. If they are not promptly treated, kidney stones may lead to serious infection and eventual impairment of function.

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