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19.4: Ureters, Urinary Bladder, and Urethra - Biology

19.4: Ureters, Urinary Bladder, and Urethra - Biology


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Communicating with Urine

Why do dogs urinate on fire hydrants? Besides “having to go,” they are marking their territory with chemicals called pheromones in their urine. It’s a form of communication, in which they are “saying” with odors that the yard is theirs and other dogs should stay away. Dogs may urinate on fence posts, trees, car tires, and many other objects in addition to fire hydrants. Urination in dogs, as in people, is usually a voluntary process controlled by the brain. The process of forming urine, which occurs in the kidneys, occurs constantly and is not under voluntary control. What happens to all the urine that forms in the kidneys? It passes from the kidneys through the other organs of the urinary system, starting with the ureters.

Ureters

As shown in Figure (PageIndex{2}), ureters are tube-like structures that connect the kidneys with the urinary bladder. In adults, ureters are between 25 and 30 cm (10 to 12 in.) long and about 3 to 4 mm (about 1/8 in.) in diameter.

Each ureter arises in the pelvis of a kidney (Figure (PageIndex{3})). It then passes down the side of the kidney and finally enters the back of the bladder.

The walls of the ureters are composed of multiple layers of different types of tissues. You can see the layers in Figure (PageIndex{4}). The innermost layer is a special type of epithelium, called the transitional epithelium. Unlike the epithelium lining most organs, the transitional epithelium is capable of flattening and distending and does not produce mucus. It lines much of the urinary system, including the renal pelvis, bladder, and much of the urethra in addition to the ureters. Transitional epithelium allows these organs to stretch and expand as they fill with urine or allow urine to pass through. The next layer of the ureter walls is made up of loose connective tissue containing elastic fibers, nerves, and blood and lymphatic vessels. After this layer are two layers of smooth muscles, an inner circular layer, and an outer longitudinal layer. The smooth muscle layers can contract in waves of peristalsis to propel urine down the ureters from the kidneys to the urinary bladder. The outermost layer of the ureter walls consists of fibrous tissue.

Urinary Bladder

The urinary bladder is a hollow, muscular, and stretchy organ that rests on the pelvic floor. It collects and stores urine from the kidneys before the urine is eliminated through urination. As shown in Figure (PageIndex{5}), urine enters the urinary bladder from the ureters through two ureteral openings on either side of the back wall of the bladder. Urine leaves the bladder through a sphincter called the internal urethral sphincter. When the sphincter relaxes and opens, it allows urine to flow out of the bladder and into the urethra.

Like the ureters, the bladder is lined with transitional epithelium, which can flatten out and stretch as needed as the bladder fills with urine. The next layer (lamina propria) is a layer of loose connective tissue, nerves, and blood and lymphatic vessels. This is followed by a submucosa layer, which connects the lining of the bladder with the detrusor muscle in the walls of the bladder. The outer covering of the bladder is the peritoneum, which is a smooth layer of epithelial cells that lines the abdominal cavity and covers most abdominal organs.

The detrusor muscle in the wall of the bladder is made of smooth muscle fibers that are controlled by both the autonomic and somatic nervous systems. As the bladder fills, the detrusor muscle automatically relaxes to allow it to hold more urine. When the bladder is about half full, the stretching of the walls triggers the sensation of needing to urinate. When the individual is ready to void, conscious nervous signals cause the detrusor muscle to contract and the internal urethral sphincter to relax and open. As a result, urine is forcefully expelled out of the bladder and into the urethra.

Urethra

The urethra is a tube that connects the urinary bladder to the external urethral orifice, which is the opening of the urethra on the surface of the body. As shown in Figure (PageIndex{6}), the urethra in a person with XY chromosomes (anatomically male) travels through the penis, so it is much longer than the urethra in a person with XX chromosomes (anatomically female). In a genetically male person, the urethra averages about 20 cm (8 in.) long, whereas, in a genetically female individual, it averages only about 4.8 cm (1.9 in.) long. In an XY individual, the urethra carries semen as well as urine, but in the XX individual, it carries only urine.

Like the ureters and bladder, the proximal (closer to the bladder) two-thirds of the urethra are lined with transitional epithelium. The distal (farther from the bladder) third of the urethra is lined with mucus-secreting epithelium. The mucus helps protect the epithelium from urine, which is corrosive. Below the epithelium is loose connective tissue, and below that are layers of smooth muscle that are continuous with the muscle layers of the urinary bladder. When the bladder contracts to forcefully expel urine, the smooth muscle of the urethra relaxes to allow the urine to pass through.

In order for urine to leave the body through the external urethral orifice, the external urethral sphincter must relax and open. This sphincter is a striated muscle that is controlled by the somatic nervous system, so it is under conscious, voluntary control in most people (exceptions are infants, some elderly people, and patients with certain injuries or disorders). The muscle can be held in a contracted state and hold in the urine until the person is ready to urinate. Following urination, the smooth muscle lining the urethra automatically contracts to re-establish muscle tone, and the individual consciously contracts the external urethral sphincter to close the external urethral opening.

Review

  1. What are ureters?
  2. Describe the location of the ureters relative to other urinary tract organs.
  3. Identify layers in the walls of a ureter and how they contribute to the ureter’s function.
  4. Describe the urinary bladder.
  5. What is the function of the urinary bladder?
  6. How does the nervous system control the urinary bladder?
  7. What is the urethra?
  8. How does the nervous system control urination?
  9. Identify the sphincters that are located along the pathway from the ureters to the external urethral orifice.
  10. What are two differences between the male and female urethra?
  11. True or False. Urine travels through the urinary system due solely to the force of gravity.
  12. True or False. Urination refers to the process that occurs from the formation of urine in the kidneys to the elimination of urine from the body.
  13. When the bladder muscle contracts, the smooth muscle in the walls of the urethra _________ .
  14. Transitional epithelium lines the:

    A. bladder

    B. ureters

    C. renal pelvis

    D. All of the above

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You deposit it in the toilets and then you flush and never see it again. Could we be making use of all the pee (and poop) we usually flush away? Watch this fun and interesting TED talk to learn more about the potential use of pee and other human excrements to grow healthier plants and people.


The Urinary Bladder

The bladder is an organ of the urinary system. It plays two main roles:

  • Temporary storage of urine – the bladder is a hollow organ with distensible walls. It has a folded internal lining (known as rugae), which allows it to accommodate up to 400-600ml of urine in healthy adults.
  • Assists in the expulsion of urine – the musculature of the bladder contracts during micturition, with concomitant relaxation of the sphincters.

In this article, we shall look at the anatomy of the bladder – its shape, vasculature and neurological control.

Fig 1 – Overview of the urinary tract.


Applied anatomy and physiology of the feline lower urinary tract

Paired ureters, urinary bladder, and urethra constitute the lower urinary tract. Oblique passage of ureters through the bladder wall results in compression of the distal ureter to preclude urine reflux. Ureters are anchored by longitudinal ureteral musculature that outlines the bladder trigone and extends into dorsal submucosa of the urethra as urethral crest. The urinary bladder can be divided into apex, body, and neck. The male urethra has penile and pelvic components, the latter is divisible into preprostatic, prostatic, and postprostatic regions. The muscle coat of the bladder-urethra forms three functional entities in craniocaudal series. These are the detrusor muscle (to effect voiding), internal urethral sphincter (smooth muscle for generating tonic resistance), and external urethral sphincter (striated urethralis m. for phasic and voluntary continence). The vesical neck is a transition region. It is part of the internal urethral sphincter by virtue of its histology and innervation, but it contains detrusor fascicles that pull it open during micturition. Viscous accommodation plus sympathetic reflex inhibition of the vesical wall allows the urinary bladder to greatly expand in volume with minimal increase of intravesical pressure, within limits. At low volumes continence can be maintained by passive resistive elements of the urethral outlet. As volume increases, sympathetic reflex activity is necessary for continence. The striated external urethral sphincter is reflexly contracted to counter abrupt elevations of intravesical pressure and to maintain continence voluntarily. The pelvic plexus conveys sympathetic and parasympathetic innervation to the urinary tract. The pudendal nerve supplies the urethra and urethralis muscle. Ureters are largely independent of innervation. Internal and external urethral sphincters are activated by spinal reflexes, sympathetic and somatic reflexes, respectively. Normal micturition (sustained detrusor contraction and sphincter inhibition) is a brainstem-driven reflex, involving a spino-bulbo-spinal pathway and a pontine micturition center that switches from urine storage to micturition. All of the reflexes depend on neural activity in tension mechanoreceptors of the bladder wall and sacral afferent fibers.


Anatomy diagram source

As is the case with most of the pelvic viscera there are differences between male and female anatomy of the urinary bladder and urethra. The urethra is held closed by the urethral sphincter a muscular structure that helps keep urine in the bladder until voiding can occur.

Urethra duct that transmits urine from the bladder to the exterior of the body during urination.

Anatomy of the urethra. Contact your doctor if you. The urinary bladder is a muscular sac in the pelvis just above and behind the pubic bone. Meatus urinarius is the most contracted part of the urethra.

Female urethra overview anatomy and function of the female urethra. Normally the urethra has no restrictions throughout the entire tube allowing the bladder to empty with an uninterrupted flow. Explore the interactive 3 d diagram below to learn more about the female urethra.

It is a vertical slit about 6 mm. One end is connected to the bladder and the other end exits the body just above the vaginal opening. Gross anatomy prostatic urethra.

Urethritis refers to inflammation of the urethra. In anatomy the urethra from greek οὐρήθρα ourḗthrā is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. The shortest and least distensible portion of the urethra is.

The urethra is a thin tube that carries urine from the bladder out of the body during urination. The arterial supply to the male urethra is via several arteries. Symptoms of a urethral condition.

The spongy urethra is the region that spans the corpus spongiosum of the penis. Urine is made in the kidneys and travels. The urethras only function in women is to carry urine out of the body.

The primary function of the urethra is to transport urine from the bladder to the tip of the penis allowing the bladder to empty when urinating. Organs of the renal system. When empty the bladder is about the size and shape of a pear.

In women the urethra is a very thin tube about 2 inches long. Membranous urethra supplied by the bulbourethral artery branch of the internal. Long bounded on either side by two small labia.

The prostatic urethra is the portion of the urethra that traverses the prostate. The external urethral orifice orificium urethræ externum. The urinary bladder and urethra are pelvic urinary organs whose respective functions are to store and expel urine outside of the body in the act of micturition urination.

Prostatic urethra supplied by the inferior vesical artery branch of the internal iliac artery which also supplies the lower part of the bladder.

Ultrasound Study Of The Urethra Springerlink

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Micturition

Micturition may also be called urination or voiding. In the case of a healthy adult, micturition usually is a random process. The random closure of the urethra happens through the M. sphincter urethrae, which is innervated by the Nervus pudendus.

The urgency to pass urine in an adult occurs when the bladder is filled to about 300–500 mL. With the increased filling, the bladder wall widens, stretching the wall the stretching is sufficient to generate sensory impulses that travel to the sacral spinal cord, which eventually passes onto the parasympathetic centers of the spinal marrow, triggering the micturition reflex. This is a spinal cord reflex over which voluntary control may be exerted. The stimulus for the reflex is the stretching of the detrusor muscle of the bladder. The bladder can hold as much as 800 mL of urine, or even more, but the reflex is activated long before the maximum is reached.

Motor impulses return along the parasympathetic nerves to the detrusor muscle. The M. detrusor vesicae are contracted in the willing micturition. Meanwhile, the ureter openings close, the blood of the uvula escapes and the Ostium urethrae externum is widened. The M. sphincter urethrae cause its contraction through the work of the detrusor muscle and, if necessary, through the support of the Heimlich maneuver, the bladder can now be emptied. In other words, the process of urination is a combination of tension (detrusor and Heimlich maneuver) and relaxation (sphincter).

Urination can be prevented by voluntary contraction of the external urethral sphincter. However, if the bladder continues to fill and be stretched, voluntary control is eventually no longer possible.


Anatomy Urethra

Hence it runs from the internal urethral orifice of the bladder to the external urethral orifice located at the tip of the glans penis. The shortest and least distensible portion of the urethra is.

Solved Fill In The Description With The Appropriate Part

Contact your doctor if you.

Anatomy urethra. The males urethra is about 18 to 20 cm 7 to 8 inches long and passes along the length of the penis before emptying. Symptoms of a urethral condition. Well compare the male and female urethrasurethrae talk about functions parts weird bits blood supply and.

This is one reason women are more affected by urinary tract infections the bacteria have a much shorter distance to travel. Then the urethral sphincter muscle relaxes and urination occurs. Explore the interactive 3 d diagram below to learn more about the female urethra.

At its emergence from the bladder. The urethra anatomy term someone gave to this part of the urethra is fossa navicularis. In anatomy the urethra from greek οὐρήθρα ourḗthrā is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males.

The urethra also functions to provide an exit for semen sperm and glandular secretions during ejaculation. It is the widest. Urethritis refers to inflammation of the urethra.

Receives the ejaculatory ducts containing spermatozoa from the testes and seminal fluid from the seminal vesicle glands and the prostatic ducts containing alkaline fluid. The last portion of the urethra after the penile urethra through which the urine travels before reaching the tip urethral meatus is the part within the head of the penis. The spongy urethra is the region that spans the corpus spongiosum of the penis.

As is the case with most of the pelvic viscera there are differences between male and female anatomy of the urinary bladder and urethra. Gross anatomy prostatic urethra. In women the urethra is about 15 inches long about 10 times shorter than in men.

Because the urethra is anatomically linked with the reproductive structures its characteristics in males are quite different from those in females. Female urethra overview anatomy and function of the female urethra. Weve looked at the other parts of the urinary system but we missed out the urethra.

The male urethra is an 18 22 cm long muscular tube that conveys urine from the urinary bladder. The urinary bladder and urethra are pelvic urinary organs whose respective functions are to store and expel urine outside of the body in the act of micturition urination. Begins as a continuation of the bladder neck and passes through the prostate gland.

The prostatic urethra is the portion of the urethra that traverses the prostate.

Overview Of The Male Anatomy

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Urinary System – Label the Kidney and Nephron

I created this version of a labeling activity for students who are learning from home during the 2020 pandemic. You will not need to hand out papers with this version! Instead, students use their Chromebook to open Google Slides and drag the labels to the correct position. I usually assign this activity after students have learned about the kidney from the chapter notes. You can also download a shorter (alternative) presentation for pandemic teaching if your schedule is shortened.

I have included three slides with this activity, though you could assign them one at a time. The first slide is an overview of the urinary system that shows the kidneys, ureters, urinary bladder, and urethra. Students drag labels to the structures on the slide. Also, the diagram shows the relationship between the aorta, vena cava, and the renal vessels. While these aren’t part of the urinary system, they are important in the physiology of the kidney.

On the second slide, viewers see a close-up of a kidney that’s been cut to show the internal structures. Renal arteries and veins become arterioles that loop around the tubules within the kidney. At the loop of Henle, these arterioles become capillaries that eventually exit through the renal vein.

I have several kidney models that students can view in class to compare with the print diagrams. You can also provide kidneys for dissection as a comparison. Even if you don’t give a formal lab on the kidney, the specimens are cheap enough for students to do a quick slice!

The final slide shows a closeup of a nephron with the proximal and distal tubules. This is a great time to revisit the process of osmosis! In addition to classwork, home learners can watch this video on EdPuzzle for an explanation on how filtration works.

I intended for this assignment to be completed after students have learned about the system. You can even encourage students to use other sources, like a Google Image search. I don’t normally grade these activities for credit, they are mainly just for practice. Assessments occur at the end of the unit.

For more advanced work, check out this case study on a baby who has a kidney problem. I also modified that activity for remote learning.


Tumours of the Urinary System

Urothelium is present in the kidney pelvis, ureters, urinary bladder, and the urethra.

Urothelial neoplasms can occur in all of these organs but >90% are in the urinary bladder.

The normal bladder wall consists of several tissue layers, the distinction of which is critical for bladder cancer staging.

The urothelium covers the inner surface of the bladder. The connective tissue layer between the urothelium and the muscular bladder wall is the lamina propria.

The staging system of urothelial neoplasms is unusual as two non-invasive lesions exist: non-invasive papillary carcinoma (pTa) and carcinoma in situ (pTis).

The invasive stages are pT1: invasion of lamina propria pT2: invasion of muscular wall pT3: invasion of perivesical fat pT4: invasion of adjacent organs.

Staging of bladder neoplasms is critical for treatment decisions, but challenging for pathologists.

This is due to the nature of transurethral tumour resection, because it always leads to fragmentation and substantial crush artefacts in the resected tissues.

The distinction between pTa and pT1 tumour can be very challenging and is subject to high interobserver variability.


Treatment of urinary tract infection

For effective management of UTI, the following principles must be recognized.

Asymptomatic patients should have colony counts greater than or equal to 10 5 per ml on at least 2 occasions before treatment is considered.

Unless symptoms are present, no attempt should be made to eradicate bacteriuria until catheters, stones or obstructions are removed.

Selected patients with chronic bacteriuria may benefit from suppressive therapy.

A patient who develops bacteriuria as a result of catheterization should be treated to re-establish sterile urine.

Efficacy of treatment should be evaluated by urine culture, one week after completion of therapy except in nonpregnant adult women with uncomplicated cystitis and uncomplicated pyelonephritis who respond to therapy.

Asymptomatic bacteriuria

Pregnancy

Pregnancy increases the risk of UTI complications. The rate of prematurity in children born to women who have bacteriuria during pregnancy is increased, and 20-40% of these patients develop pyelonephritis. Successful therapy of these patients with bacteriuria decreases the risk of symptomatic infection by 80-90%. Therefore, all women should be screened twice during pregnancy for asymptomatic bacteriuria. All bacteriuric patients should be treated for seven days, with follow-up cultures to identify relapses. In selecting therapy, risk to foetus should be considered. Amoxicillin or cephalexin usually suffice.[22]

Children

Asymptomatic bacteriuria in young children and school-aged girls may signify underlying vesicoureteral reflux. Therefore, asymptomatic bacteriuria should be treated with follow-up urologic evaluation after six weeks.

General population

Asymptomatic bacteriuria in men and nonpregnant women, a common condition in the elderly,[23] does not appear to cause renal damage in the absence of obstructive uropathy or vesicoureteral reflux and therefore it should not be treated.

Instrumentation of genitourinary tract should be avoided in patients with asymptomatic bacteriuria or, if necessary done under the cover of prophylactic antibiotic therapy. Selected high-risk patients (renal transplantation or neutropenia) may benefit from therapy for asymptomatic bacteriuria.

Diabetis mellitus

Patients with asymptomatic bacteriuria who have conditions predisposing to papillary necrosis such as diabetis mellitus must be considered at risk of potentially harmful extension of infection to the kidney which may accelerate interstitial damage. Treatment is similar to that used for sysmptomatic patients.

Uncomplicated cystitis

This is almost exclusively a disease of sexually active women mostly between the ages of 15 and 45 years. Although reinfection is common, complications are rare.

Short course therapy

Infections truly confined to bladder or urethra respond as well to single-dose or short-course (3 day) therapy as to conventional therapy for 10-14 days. However, it has been observed that three- day therapy is more effective than single-dose therapy.[24] A three-day regimen of amoxillin-clavulinate was found to be significantly less effective than a three-day regimen of ciprofloxacin in treating uncomplicated UTIs in women.[25] However, resistance has increased to various antimicrobials and more than one quarter of E. coli strains causing acute cystitis are resistant to amoxicillin, sulfa drugs and cephalexin and resistance to co-trimoxazole is now approaching these levels. Resistance to fluoroquinolones is also rising. Thus, knowledge of local resistance pattern is needed to guide empirical therapy.[26]

Seven-day regimen

A longer course of therapy for cystitis should be given to patients with complicating factors that lead to lower success rates and a higher risk of relapse. These factors include a history of prolonged symptoms (more than seven days), recent UTI, diabetes, age above 65 years and use of a diaphragm. Importantly, both elderly and diabetic women frequently have concurrent renal infection, thus short course therapy should not be used in them.

Recurrent cystitis (re-infections)

Some women especially whose periurethral and vaginal epithelial cells avidly support attachment of coli-form bacteria suffer from recurrent episodes of cystitis in the absence of recognized structural abnormalities of the urinary tract. Management in such women include the following:

Continuous low dose prophylaxis and

Postcoital prophylaxis is the most helpful for patients who associate recurrent UTIs with sexual intercourse. In these women, a single dose of an antimicrobial after sexual intercourse significantly reduces the frequency of UTIs.

Women with recurrent UTIs (more than three UTIs per year) benefit from thrice weekly bed time antibiotic therapy. Such therapy significantly reduces the frequency of episodes of cystitis from an average of 3 per patient-year to 0.1 per patient-year.[27] This regimen is known as continues low dose prophylaxis.

Women with fewer than three UTIs per year can be offered self-administered treatment. At the first sign/symptom of a UTI, such women should take a single-dose regimen of TMP-SMX or a fluoroquinolone. This is both effective and well tolerated.[28]

Several prospective studies have demonstrated the efficacy of either nitrofurantoin 50 mg or nitrofurantoin macrocrystals 100 mg at bed time for prophylaxis against recurrent reinfection of urinary tract. Such a regimen has little if any effect on the faecal flora and presumably acts by providing intermittent urinary antibacterial activity.

Perhaps, the most popular prophylactic regimen currently used in women susceptible to recurrent UTI is low-dose TMP-SMX as little as half a tablet (trimethoprim, 40 mg, sulfamethoxazole, 200 mg) three times weekly at bed-time is associated with an infection frequency of less than 0.2 per patient-year. The efficacy of this prophylactic regimen appears to remain unimpaired even after several years. Similar to TMP-SMX, the fluoroquinolones may be used in a low-dose prophylactic regimen. The efficacy of these regimens is further delineated by their potency in preventing UTI in the far challenging population of kidney transplant recipients.

Acute bacterial pyelonephritis

In this setting, blood and urine cultures should be obtained.

Out-patient therapy

For uncomplicated acute pyelonephritis, a fluoroquinolone or co-trimoxazole is the drug of choice for initial therapy. After culture results are available, a full 10-14 day course of the antimicrobial to which the organism is susceptible should be instituted.[29]

In-patient therapy

Patients who require admission to the hospital should be treated initially with a third-generation cephalosporin or a fluoroquinolone and gentamicin 4-7 mgs every 24 h if the urine shows Gram-negative bacilli on microscopy. If gram-positive cocci are seen in the urine, intra-venous ampicillin 1g every 4 hours should be given in addition to gentamicin, to cover the possibility of enterococcal infection. If no complications ensue and patient becomes afebrile, the remaining two-week course can be completed with oral therapy.

However, persistent fever, persistent bacteriuria in 48-72 h or continual signs of toxicity beyond three days of therapy suggest the need for evaluation to exclude obstruction, metastatic focus or formation of a perinephric abscess. Adequate fluids must be given to maintain adequate arterial perfusion. Failure to respond to seemingly appropriate therapy suggests the possibility of underlying pus. Examination by US or CT may disclose an obstructed ureter or perinephric abscess, both of which require surgical drainage.[30]

Recurrent renal infections (Relapses)

Chronic bacterial pyelonephritis is one of the most refractory problems as relapse rates are as high as 90% occur.

Risk factors

To improve the success rate, it is important to repair any correctable lesions, that obstructions to urine flow be relieved and that foreign bodies (indwelling urinary catheters or renal staghorn calculi) be removed.

If the risk factors cannot be corrected, long-term eradication of bacteriuria is almost impossible. To attempt eradication in such instances leads only to the emergence of more resistant strains of bacteria or fungi. In such case, one must be resigned to treatment of symptomatic episodes of infection and to suppression of bacteriuria in selected patients.

Acute symptomatic infection

The treatment of acute symptoms and signs of UTI in a patient with chronic renal bacteriuria is the same as for patients with acute bacterial pyelonephritis.

Prolonged treatment

Some patients with relapsing bacteriuria respond to six weeks of antimicrobial therapy. This is especially true of patients with no underlying structural abnormality and of men with normal prostatic examination.

Suppressive therapy

Patients who fail the longer therapy, who have repeated episodes of symptomatic infection or who have progressive renal disease despite corrective measures, are candidates for suppressive antibiotic therapy. These patients should have two to three days of specific high-dose antimicrobial therapy to which their infecting bacteria are susceptible to reduce the colony counts in their urine. The preferred agent for long-term suppression is methenamine mandelate. Alternative therapy is cotrimoxazole, two tablets twice daily or nitrofurantion 50-100 mg twice daily.[31]

Prognosis

Although UTIs are a common cause of appreciable morbidity, they do not play a major role in the pathogenesis of end-stage renal disease. Patients who come to renal replacement therapy because of chronic bacterial pyelonephritis almost always have an underlying structural defect. Most often, the lesion is chronic atrophic pyelonephritis associated with vesicoureteric reflux that started in infancy. The role of surgical correction of vesicoureteral reflux is not clear, but what is certain, is the importance of meticulous control of infection in children to prevent progressive renal scarring and renal failure by early adulthood.

Prostatitis

Acute bacterial prostatitis

The drug of choice is cotrimoxazole or fluoroquinolone. However, treatment must be ultimately based on an accurate microbiological diagnosis and continued for 30 days to prevent chronic bacterial prostatitis. Urethral catheterization should be avoided. If acute urinary retention develops, drainage should be by supra-public needle aspiration or if prolonged bladder drainage is required by a suprapubic cystostomy tube.

Chronic bacterial prostatitis

The hallmark of chronic bacterial prostatitis is relapsing UTI. It is most refractory to treatment. Although erythromycin with alkalinization of urine is effective against susceptible Gram-positive pathogens, most instances of chronic bacterial prostatitis are caused by gram-negative enteric bacilli. Cotrimoxazole or fluoroquinolone is the drug of choice.

Approximately 75% of patients improve and 33% are cured with 12 weeks of cotrimoxazole therapy. For patients who cannot tolerate cotrimoxazole or fluoroquinolone, nitrofurantoin 50 or 100 mg once or twice daily can be used for long-term (6-12 months) suppressive therapy.[32]

Nonbacterial chronic prostatitis

Therapy is difficult because an exact etiology has not been identified. Owing to a concern for C. trachomatis, Ureaplasma urealyticum and other fastidious and difficult to culture organism, many experts recommended a six- week trial of tetracycline or erythromycin. Symptomatic therapy with NSAIDs and alpha-receptor blockers has also been used.

Catheter-associated infection

Urinary catheters are valuable devices for enabling drainage of the urinary bladder but their use is associated with an appreciable risk of infection. For a single (in-and-out) catheterization, the risk is small (12%), though this prevalence is much higher in diabetic and elderly women. However, bacteriuria occurs in virtually all patients with indwelling catheters within three to four days unless placement is done under sterile conditions and a sterile, closed drainage system is maintained. The use of a neomycin-polymyxin irrigate does not prevent catheter-associated infection.

Catheter-associated bacteriuria should only be treated in the symptomatic patient. When the decision to treat is made, removal of the catheter is an important aspect of therapy, because if an infected catheter remains in place, relapsing infection is very common. The interaction between the organisms and catheter cause the organism to form a biofilm, an area in which antibiotics are unable to completely eradicate these organisms. The empiric therapy of these infections is similar to that of complicated UTIs. Patients who rapidly respond to the therapy may be treated only for seven days.

The use of catheters impregnated with antimicrobial agents reduces the incidence of asymptomatic bacteriuria in patients catheterized for less than two weeks. Despite precautions, the majority of patients catheterized for more than two weeks eventually develop bacteriuria.[33]

Fungal urinary tract infection

The most common form of fungal infection of urinary tract is that caused by Candida species. Such infections usually occur in patients with indwelling catheters who have been receiving broad-spectrum antibiotics, particularly if diabetes mellitus is also present or corticosteroids are being administered. Although most of these infections remain limited to the bladder and clear with the removal of the catheter, cessation of antibiotics and control of diabetes mellitus, the urinary tract is the source of approximately 10% of episodes of candidemia, usually in association with urinary tract manipulation or obstruction.[34] Spontaneously occurring lower UTI caused by Candida species is far less common, although papillary necrosis, caliceal invasion and fungal ball obstruction have all been described as resulting from ascending candidal UTI that is not related to catheterization.

Hematogenous spread to the kidney and other sites within the genitourinary tract may be seen in any systemic fungal infection, but it occurs particularly in coccidioidomycosis and blastomycosis.[35] In immunosuppressed patients, a common hallmark of disseminated cryptococcal infection is the appearance of this organism in the urine. Cryptococcus neoformans commonly seeds the prostate and far less commonly may cause a syndrome of papillary necrosis, pyelonephritis and pyuria akin to that seen in tuberculosis.

There are no criteria to distinguish between colonization or infection with candiduria, so the following approach is adopted for the treatment.

In patients with catheter-associated candidal UTI, removal of the preceding catheter, insertion of a three-way catheter and infusion of an amphotericin rinse for a period of three to five days eradicates greater than 50% infections.[36] In patients with candiduria without an indewelling catheter, fluconazole 200 to 400 mg /day for 10 to 14 days should be given. In a population of organ transplant patients, such an approach has been successful in more than 75% of patients with candiduria.[37]

Any patient with candiduria who has to undergo instrumentation of the urinary tract requires systemic therapy with amphotericin or fluconazole to prevent the consequences of transient candidemia.


Watch the video: Biology of the Kidneys and Urinary Tract. Merck Manual Consumer Version (July 2022).


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