Disorders of the Bladder and Urethra
The lower urinary tract consists of the bladder and urethra. If left untreated, disorders of the bladder or urethra can interfere with normal functioning of the urinary tract and lead to kidney damage.
The urethra can become narrowed by scar tissue following catheter placement, surgery, injury, or repeated episodes of urethritis (see page 286). This condition, called urethral stricture, is a common problem following long-term catheter placement. Urethral stricture can interfere with urination and ejaculation. It also can damage the kidneys by causing back pressure (buildup of ﬂuid) in the uri- nary tract. Urethral stricture also may be a factor in the development of urinary tract infections.
Urethral stricture can be treated in the doctor’s ofﬁce by widening the urethra from within with a thin, ﬂexible instrument called a dilator. Sometimes the scar tissue must be removed surgically using a cystoscope, or a por- tion of the urethra must be removed surgically. Laser ther- apy also may be used to remove the scar tissue. Depending on where the stricture is located, a urethral stent (a tiny springlike device that holds the urethra open) can be inserted to keep the passageway open. However, if the stricture is too close to the sphincter muscle (which pre- vents leakage of urine from the bladder), a stent cannot be used. In some cases the affected segment of the urethra may be surgically reconstructed using tissue taken from another part of the body.
Urethral stricture is a condition in which the urethra (the tube that carries urine out of the bladder) is narrowed, potentially interfering with the ﬂow of urine and with ejaculation. The urethra can become narrowed when scar tissue forms after some medical procedures (such as placement of a catheter), surgery, injury, or recurring infections.
Bladder cancer is the fourth most common type of cancer in men. Transitional cell carcinoma, which develops from the cells that line the bladder walls, is the most common type of bladder cancer. This type of cancer also can occur in the kidneys, the ureters, and the portion of the urethra nearest the bladder.
Transitional cell carcinoma that remains conﬁned to the surface of the bladder lining is called superﬁcial bladder cancer. Superﬁcial bladder cancer is the most common type of transitional cell carcinoma (75 to 80 percent of new cases) and is easy to treat, but it tends to recur. In some cases the cancer spreads beyond the bladder lining and invades the muscular wall of the bladder. This is called inva- sive bladder cancer. The tumor may continue to grow through the bladder wall and spread to nearby organs. Bladder cancer cells also can spread to surrounding lymph nodes and to distant organs such as the lungs or the bones.
Symptoms of bladder cancer can be the same as those for a bladder infection or other urinary tract disorder. Therefore you should talk to your doctor as soon as possible if you experience any symptoms. The most common symptoms of bladder cancer include blood in the urine, painful urination, frequent urination (without an increase in ﬂuid intake), and an urge to urinate with little urine output. If your doctor thinks you may have bladder cancer, he or she will examine the inside of the bladder with a viewing tube called a cystoscope (see “Diagnostic Procedures,” Cystoscopy, page 298) and use other imaging techniques to deter- mine whether the cancer has spread.
Surgery is the most common treatment for bladder cancer. Superﬁcial bladder cancer can be treated with transurethral resection, in which the tumor is surgi- cally removed through a cystoscope. With invasive bladder cancer, all or part of the bladder is removed using a surgical procedure called cystectomy. Often, sur- rounding lymph nodes, the prostate gland, and the seminal vesicles also are removed. Additional treatment may include radiation therapy, chemotherapy (treatment with powerful anticancer drugs), or immunotherapy (treatment in which the body’s immune system is stimulated to destroy cancer cells), depend- ing on where the cancer has spread and how advanced it is.
When the bladder must be removed, the doctor creates an alternative method for storing and passing urine. The doctor often will use an isolated piece of the person’s small intestine to create a new channel between the ureters and an open- ing in the wall of the abdomen (called a stoma) through which urine can pass. A ﬂat bag is attached to the stoma to collect urine, and the person empties the bag as needed. A portion of small intestine also can be used to create a storage pouch inside the body (instead of an external bag), which the person drains by inserting a catheter through the stoma. The storage pouch also can be attached to the remaining portion of the urethra to allow the person to urinate through the urethra.
Until recently, nearly all men experienced erectile dysfunction after bladder removal surgery, but surgical improvements have reduced the likelihood of this side effect. However, men who have had their prostate gland and seminal vesi- cles removed no longer produce semen, so they do not ejaculate when they have an orgasm, and they are infertile.
Other Urinary Tract Disorders
Other possible disorders of the urinary tract include the following:
• Polycystic kidney disease. Polycystic kidney disease (PKD) is a genetic disor- der in which numerous ﬂuid-ﬁlled cysts (abnormal lumps or swellings) grow in the kidneys. These cysts can slowly displace much of the functional tissue of the kidneys, reducing kidney function and leading to kidney failure. People with PKD can have the disease for decades without developing symptoms. The most common symptoms are pain in the back and the sides (between the ribs and the hips) and headaches. People with PKD also may develop urinary tract infections (see page 286), hematuria (see page 291), cysts in other organs, high blood pressure (see page 217), and kidney stones (see page 289). Doctors use ultrasound scanning (see “ Diagnostic Procedures,” page 297) to look for cysts in the kidneys, especially in people who have a family history of
PKD. Although there is no cure for PKD, treatment can ease the symptoms and prolong life.
• Acquired cystic kidney disease. People who have a long history of kidney dis- ease (especially if they require dialysis) are likely to develop cystic kidney disease similar to PKD (above). The cysts may bleed. People with acquired cystic kidney disease are twice as likely to develop renal cell cancer (see “Kidney Cancer,” page 293).
• IgA nephropathy. This kidney disorder is caused by deposits of the protein immunoglobulin A (IgA) inside the ﬁltering mechanisms (glomeruli) within the kidney. The IgA protein blocks the normal ﬁltering process, which causes blood and protein to remain in the urine and also causes swelling in the hands and feet. IgA nephropathy is a chronic glomerular disease (see page 290) that may progress over a period of 10 to 20 years.
• Analgesic nephropathy. This kidney disease results from long-term use of analgesics (painkillers) and gradually leads to end-stage renal disease (see page 293). Single analgesics such as aspirin have not been found to cause kid- ney damage. However, medications that combine two or more painkillers (such as aspirin and acetaminophen) with caffeine or codeine are most likely to damage the kidneys. People who already have kidney disease must use cau- tion when taking any painkiller.
Urinary tract disorders often can be diagnosed through blood and urine tests. Blood tests can show when the kidneys are failing to adequately remove waste products. Urine tests (urinalysis) can show whether there is bleeding in the uri- nary tract, whether bacteria have infected the urinary tract, or whether the kid- neys are functioning properly. A small sample of urine can be quickly tested for the presence of protein, sugar, blood, and other substances using a dipstick (a strip of paper coated with test chemicals that can be dipped into the urine and checked immediately for results). The relative amount of acid in the urine (pH) can be determined in the same way. Other urine tests require a person to collect all the urine he or she produces over a 24-hour period. Special imaging proce- dures also may be needed to examine the structure of the kidneys, ureters, blad- der, and urethra. The following are the most common tests for diagnosing urinary tract disorders:
• Serum creatinine. This blood test measures the amount of creatinine, a waste product that results from eating meat and from muscle repair. High levels of creatinine in the blood indicate that the kidneys are not working properly.
• Blood urea nitrogen (BUN). Urea nitrogen is another by-product of protein digestion. As with serum creatinine, high BUN levels on a blood test indicate reduced kidney function.
• Creatinine clearance. A creatinine clearance test compares the amount of cre- atinine present in a 24-hour urine sample with creatinine levels in blood to determine how much blood the kidneys have ﬁltered over a 24-hour period.
• Speciﬁc gravity. This urine test measures the extent to which the kidneys can concentrate the urine they produce. If the speciﬁc gravity is lower than nor- mal, it suggests that the kidneys are not functioning efﬁciently.
• Urinary sediment. Normal urine contains a small number of cells and other materials shed during passage through the urinary tract. Examining the num- ber and type of these substances can help identify speciﬁc disorders. For example, the presence of white blood cells and bacteria indicates infection. The presence of white blood cells also may indicate a tumor. Crystals appear when the urine is not acidic enough to dissolve them or when the concentra- tion of crystals in the urine is abnormally high. Casts (cylindrical clumps of material that form in and come from the tubules in the kidney) distinguish kidney problems from disorders of the ureter, bladder, and urethra and help identify the diseased area of the kidney.
• Intravenous urography. This series of contrast medium-enhanced X rays allows doctors to view the interior structures of the urinary tract. This test sometimes is called an intravenous pyelogram, or IVP. The contrast medium is injected into a vein, and X rays are taken as it reaches the kidneys and is ﬁltered out. When the contrast medium has ﬁlled your bladder, you will be asked to urinate, and X rays will be taken to see if any of the contrast medium remains in your bladder. This procedure is most often performed to look for stones in the kidney or the bladder, cysts in the kidney, tumors, an enlarged prostate, or other possible sources of blockage.
• Cystoscopy. For this test, a thin, rigid or ﬂexible tube (with or without a video camera attached) is passed through the urethra into the bladder. This proce- dure is required to rule out a possible bladder tumor.
• Retrograde pyelogram. This procedure usually is performed during a cys- toscopy and is used when poor kidney function limits the value of intravenous urography. For this test, contrast medium is injected directly from the bladder into the ureters through the cystoscope. The contrast medium allows the doc- tor to check for blockages or tumors.
• Ultrasound scanning. Ultrasound scanning (also called ultrasonography or a “sonogram”) is an imaging technique that allows doctors to see the outline and the interior of the kidneys and, to a lesser extent, the bladder. This proce- dure offers a noninvasive method of distinguishing between cysts and tumors of the kidney, checking for urinary tract obstruction, detecting inﬂammation and ﬂuid collection around the kidneys, and identifying the best location for a planned biopsy.
• Computed tomography (CT) scanning. CT scanning is a diagnostic technique that uses a computer and low-dose X rays to produce detailed cross-sectional
images of body tissues that are displayed on a video monitor. This technique is performed with or without a contrast medium (a dye) to detect stones and tumors in the urinary tract.
• Magnetic resonance imaging (MRI). MRI is a diagnostic technique that uses a computer, a powerful magnetic ﬁeld, and radio waves to produce detailed two- and three-dimensional images of body tissues that are displayed on a video monitor. This technique is used to detect tumors in the kidneys and bladder.