Which procedure involves the examination of the ureters and the renal pelvises

8.2.1 Imaging Diagnosis

Radiological explorations represent the main diagnostic modality. Approximately 50–70% of patients with TCC have lacunar images on intravenous urography (IVU) (Figs 8.3 and 8.4).

However, less than half of the filling defects seen on IVU prove to be malignant (Bagley and Rivas, 1990). The urographic differential diagnosis is made with benign conditions: radiolucent stones, blood clots, fibroepithelial ureteral polyps (Fig. 8.5), irregular renal papillae, nephrogenic adenomas, subepithelial hematomas, extrinsic vascular compressions, cystic pyelitis or ureteritis, tuberculosis, endometriosis, and amyloidosis.

Retrograde pyelography is indicated if there is a poor visualization of the upper urinary tract or when the contrast agent cannot be administered intravenously (allergic patients, renal failure, or urographic nonfunctioning kidney) (Fig. 8.6). Although this method provides a diagnostic accuracy of approximately 75% (Murphy et al., 1981), false-negative results are described with an incidence of 25% (Keeley, 1997a). It is generally recommended to use a diluted contrast agent for retrograde ureteropyelography (1/2–1/3 compared to the initial concentration) in order to allow the visualization of the filling defects (Fig. 8.7).

Antegrade pyelography is not recommended in patients with suspicion of TCC because of the risk of secondary tumor seeding along the percutaneous tract.

Ultrasonography can detect kidney stones, being useful for the differential diagnosis of filling defects visualized on urography, but its accuracy is reduced regarding the detection of tumors developed in the upper urinary tract.

Computed tomography (CT) is used especially for the differential diagnosis of a filling defect discovered on urography. This method can differentiate a radiolucent stone (80–250 Hounsfield units – HU) from tumoral tissue (10–70 HU) (Fig. 8.8).

The sensitivity of CT is approximately 90%, but it cannot differentiate between a T1 and a T2 tumor. The percentage of false-negative results regarding the assessment of local tumoral invasion is 59%. Still, the CT exam is very useful for identifying the locoregional extension (Fig. 8.9) or lymph node masses (McCoy et al., 1991).

Nuclear magnetic resonance shows similar results to the CT exam regarding the diagnosis of TCC (Milestone et al., 1990), proving to be useful in certain patients with nonfunctioning kidneys or with severe allergies to contrast agents.

Sorghum

Ingestion of Sorghum species and certain hybrid Sudan grasses has been associated with the development of an ataxia-cystitis syndrome.189,190 This is, however, a very rare event. The toxicity occurs when horses graze the plants. More cases occur when the plant is young and rapidly growing, but mature and second-growth plants also have been incriminated. Horses being fed well-cured Sorghum species hay have not developed signs of toxicity. Occurrence of toxicity may increase during seasons of medium to high rainfall, but no cases have been recognized following the date of the first frost. Signs of toxicity may develop following a grazing period of 1 week to several months.189

k. Corynebacterium renale, C. cystitidis, and C. pilosum Infections (Pyelonephritis; Posthitis and Ulcerative Vulvovaginitis)

Signs and Symptoms

Symptoms alone do not permit a differential diagnosis as many Enterobacteriaceae cause symptoms similar to those seen with other bacterial infections.

Urinary tract infections involving Citrobacter and Enterobacter are indistinguishable from those caused by other gram-negative bacteria. Lower urinary tract infections involve the urethra or bladder (urethritis or cystitis, respectively) and are more common in women than men. The most common symptom of urethritis or cystitis is pain during urination and a frequent need to urinate. With cystitis, there is often pain above the pubic bone and in the lower back. Urine is often cloudy and may contain blood. Individuals with indwelling catheters may have bladder infections with no symptoms until a fever develops or the infection spreads to the kidneys. Upper urinary tract infections involve the ureters or kidneys (ureteritis or pyelonephritis, respectively). Kidney infections often produce sudden chills, fever, pain in the lower back, nausea, vomiting, and may involve painful urination (http://www.merck.com/mrkshared/mmanual_home/sec11/127.jsp).

The symptoms of respiratory tract infections are not specific to Citrobacter or Enterobacter species and are similar to those seen with Streptococcus pneumoniae. Symptoms, which generally occur gradually, include malaise, slowly increasing fever, and/or chills and a cough. The cough will eventually produce sputum, which may be discolored and foul smelling, and the patient may experience shortness of breath. In cases of chronic pneumonia or lower respiratory tract infection, the individual may also experience appetite and weight loss Ray and Ryan (1984). A chest radiograph and culture of sputum samples are useful in identifying the etiological agent.

Gastroenteritis due to Citrobacter and Enterobacter infections produces symptoms similar to those that occur with other enteropathogenic bacteria such as E. coli or Shigella. The symptoms generally appear suddenly, with loss of appetite, nausea, vomiting, intestinal/abdominal cramps, gas, and watery diarrhea. A fever and mylagia may also be present. If overly dehydrated the affected individual may experience a drop in blood pressure with progression to shock from loss of electrolytes. Patients with hemorrhagic colitis (infection of the large intestine) may experience little or no fever and bloody and/or watery diarrhea. Some may develop hemolytic-uremic syndrome that can lead to kidney failure, anemia, seizures, strokes, and nerve or brain damage Ryan (1984).

Sepsis occurs when bacterial numbers in the blood are too high for efficient removal by white blood cells leading to septic shock. Bacteria normally enter the bloodstream and cause sepsis when there is an infection elsewhere in the body. Symptoms include fever, chills, shaking, nausea, vomiting, diarrhea, and general malaise. The patient will normally have a high white blood cell count. Sepsis can also lead to infections in other parts of the body, such as the brain (meningitis), heart (endocarditis), bone (osteomyelitis), or soft tissue (http://www.merck.com/mrkshared/mmanual_home/sec17/176.jsp).

Meningitis and brain abscesses caused by Citrobacter and Enterobacter most commonly occur in neonates and present with fever, vomiting, lack of appetite, irritability, high-pitched crying, and seizures. The forehead may bulge and the head may swell. In those older than one year of age, fever, irritability, drowsiness, confusion, and a painful stiff neck are common. The symptoms can progress to coma and death very rapidly. A lumbar puncture is required to determine the cause of infection if meningitis is suspected (http://www.merck.com/mrkshared/mmanual_home/sec17/176.jsp) (http://www.merck.com/mrkshared/mmanual_home/sec23/253.jsp).

Birds

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Cryptosporidium meleagridis is most commonly observed among turkeys. The organism affects the epithelial cells of the small intestine and causes a severe diarrheal disease, particularly in poults. Additionally, birds may present with lethargy, anorexia, and huddling, and moderate flock mortality rates may be observed.

C. baileyi causes bursitis and cloacal infection in chickens that may be detected histologically. However, this organism rarely leads to clinical disease.

C. baileyi has, however, been reported to cause moderate to severe ocular and respiratory disease in more than 30 species of birds, including chickens, turkeys, and a number of caged, aviary, and pet bird species from multiple genera. Affected birds may present with oculonasal discharge, sneezing, and/or cough. Histopathologic evaluation of these birds may demonstrate sinusitis, air sacculitis, tracheitis, and/or pneumonia.

Occasionally, Cryptosporidium species have been identified as a cause of nephritis and ureteritis in a variety of avian species. Clinical signs vary but may include anorexia, weight loss, and weakness characterized by pelvic limb paresis. Affected birds are typically immune suppressed by concurrent viral infections.

Chinchillas

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As with rabbits, cryptosporidiosis among chinchillas appears to be confined to younger animals. Despite relatively frequent anecdotal and unpublished reports of cryptosporidiosis among chinchillas, only a few publications can be found in the peer-reviewed literature.

Affected animals develop anorexia, diarrhea, dehydration, and lethargy. Death may occur, in spite of supportive care. Clinical cryptosporidiosis appears most common among stressed chinchillas such as those kept under poor conditions.

Ferrets

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Ferrets may be clinically or subclinically infected with Cryptosporidium. Clinical cryptosporidiosis appears to be more prevalent among juvenile ferrets and is characterized by anorexia, depression, and diarrhea. Death may occur in advanced cases.

Guinea pigs

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Despite the relatively high prevalence of C. wrairi in guinea pigs, clinical signs attributable to this organism are relatively rare. When clinical signs do occur, they are most common in juvenile guinea pigs, which present with failure to gain weight, weight loss, diarrhea, and death.

Hamsters

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Several peer-reviewed articles discuss both spontaneous and experimental cryptosporidiosis in hamsters. As with other animals, this condition tends to affect neonatal and juvenile hamsters to a greater degree than adults. Furthermore, cryptosporidiosis is more likely in immune suppressed adult hosts and/or those with concurrent disease.

Clinically affected hamsters present with diarrhea and may develop hematochezia. Lethargy, listlessness, and death may occur, particularly among neonatal hamsters.

Mice

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Clinical cryptosporidiosis is rarely encountered in pet, laboratory, or wild mice. C. muris inhabits the gastric glands and appears to cause subclinical infection.

Rabbits

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C. cuniculus tends to cause subclinical infection in adult rabbits. C. cuniculus was first described in an asymptomatic adult female rabbit that had intestinal cryptosporidiosis. The rabbit demonstrated mild pathology of the ileum with blunted villi, a decrease in the villus-to-crypt ratio, and mild edema in the lamina propria. Later that year, two more rabbit cases were described in which intestinal pathology was similar to that in the first case.

Several published reports describe severe and fatal cryptosporidiosis among juvenile and weanling rabbits. Affected rabbits typically are younger than 3 months of age and develop diarrhea, anorexia, lethargy, and occasionally death. Histopathologic examination has identified atrophy of the villi of the ileum.

Rats

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As with mice, clinical cryptosporidiosis is rarely reported in rats.

Reptiles

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C. serpentis is responsible for gastric infection in snakes. These animals typically develop anorexia, midbody swelling, lethargy, and weight loss. Infection with this organism may also occur in lizards; however, such infections are typically subclinical.

C. varanii is typically an intestinal infection of lizards. Juveniles are affected more frequently than adults. This occurs with anorexia, weight loss, abdominal swelling, and death.

Ectopic ureter

An ectopic ureter is a congenital condition where the ureters do not empty into the trigone region of the bladder; incontinence occurs when they empty into an area distal to the high pressure zone of the urethra. Ectopic ureters may be unilateral or bilateral and are more often reported in female dogs;235 they have also been reported in cats.236-239 Incontinence is not always present,237 especially in males.240 Dilation of the affected ureter and renal pelvis from ureteritis and pyelonephritis can occur secondary to ascending bacterial infection.

The radiographic and ultrasonographic diagnoses of ectopic ureter were compared in a series of 14 dogs136; the ectopic ureters were unilateral in 5 dogs and bilateral in 9 dogs. It was concluded that there was no difference in detection rate (91%) between radiography and ultrasonography by an experienced sonographer. Radiographic studies (intravenous pyelography, vaginourethrography [females], urethrography [males]) were conducted just before the ultrasound examination, and all studies were performed with anesthesia. Before the ultrasonographic study, the bladder was also moderately distended with saline. Termination of the 5 normal ureters in this investigation was considered normal when the vesicoureteral junction or a normal ureteral jet was observed. Two ectopic ureters of the 14 dogs were not detected with either radiography or ultrasonography. The renal pelvis or ureter was dilated in 10 (43%) ectopic ureters, which helped with diagnosis. Other ultrasonographic findings that helped confirm an ectopic ureter included absence of a ureteral jet, visualization of the ectopic ureter passing caudal to the bladder trigone, visualization of the ectopic ureter opening into the urethra close to the bladder neck (5 instances), and visualization of the ectopic ureter opening into the prostatic urethra (2 cases). Fig. 16.33 illustrates a case of bilateral ectopic ureter in a dog. Some dogs with ectopic ureter have concurrent renal dysplasia that may be unilateral, occurring on the side of the ectopic ureter. Finding a single small and irregularly shaped kidney that has characteristics of renal dysplasia suggests that the ureter on that side is ectopic.

It has been reported that normal ureteral jets are better visualized with either conventional or color Doppler ultrasonography if the specific gravity of the urine in the bladder is different from that in the ureter.132,227,228 Therefore, filling the bladder with saline of lower specific gravity than ureteral urine will enhance visualization of normal ureteral jets. An alternative approach is to empty the bladder, withhold water for several hours to concentrate bladder urine, and then allow access to water, or intravenously administer a diuretic during the study to produce dilute ureteral urine. Failure to observe normal ureteral jets under these circumstances suggests the possibility of an ectopic ureter, whereas visualization of normal ureteral jets helps confirm normalcy.

Ectopic ureters may not be visualized on ultrasonographic studies for a variety of reasons. Detection of ectopic ureters may be difficult when there is an intrapelvic bladder neck because of the interference of overlying bone.241 In addition, a normal ureteral jet may not be observed in all normal dogs or in dogs with ureteral infection or obstruction. Therefore standard urography, urethrography, or vaginourethrography are often required for diagnosis, but not all ectopic ureters are seen even on these studies. Digital fluoroscopic urography, contrast-enhanced CT, and uroendoscopy can be used when other methods fail,242,243 but these techniques may not be available to all veterinary practitioners. Therefore one must carefully consider the clinical information, laboratory data, and the findings on available imaging procedures to reach the correct diagnosis. Using uroendoscopy to confirm the presence of an ectopic ureter has a real advantage over the other methods because an intramural ectopic ureter can be ablated during the procedure, potentially leading to resolution of incontinence. Furthermore, direct visualization of the ureteral opening is a more sensitive method of detecting ectopic ureters and should be considered in young incontinent dogs even when it is believed that the ureters are not ectopic on the basis of other radiographic or ultrasonographic studies.

Imaging Studies

Survey abdominal radiography may be the most sensitive, readily available diagnostic tool for detection of ureterolithiasis. Careful scrutiny of the retroperitoneal space often reveals tiny mineral opacities more difficult to visualize with ultrasound (Figure 41-5). Survey radiographs also allow comparison of kidney size and usually demonstrate nephrolithiasis if present.

The chronically obstructed kidney often is small, hard, and irregular on abdominal palpation and appears sonographically as an end-stage kidney. Evidence of obstruction (e.g., a ureterolith or hydronephrosis) may or may not be detected. The acutely obstructed kidney usually is normal to large in size, painful, and resilient on palpation. Ultrasonographically, renal parenchymal architecture may be relatively normal or may show evidence of chronic change (e.g., blurring of the corticomedullary junction or small cortical infarctions). The renal pelvis and/or ureter may be dilated to varying degrees.

The normal, nondilated renal pelvic space and ureter usually are not visualized with ultrasound; however, even slight (1-mm to 2-mm) dilation in the renal pelvis is detectable by a skilled operator.28,29 Ureteral dilation may be more challenging to detect, depending on degree and location of the dilated segment. Dilation of the ureter and/or renal pelvis usually is apparent ultrasonographically within 3 to 4 days of obstruction (Figure 41-6). Documentation of moderate to marked (4 mm or less) renal pelvic and/or ureteral dilation can confirm suspicion of unilateral or bilateral ureteral obstruction rapidly, although the sonographic appearance does not confirm complete obstruction. Mild to moderate (less than 4 mm) renal pelvic or ureteral dilation can be consistent with obstruction or with pyelonephritis/ureteritis.

AUO results in a significant pressure increase in the renal pelvis, which causes compression of the renal parenchyma within the relatively noncompliant renal capsule. This increase in parenchymal pressure increases resistance to afferent blood flow in the kidney, a measure that can be assessed via Doppler ultrasonography. Measurement of the resistive index (calculated resistance to blood flow through the arcuate arteries) gives high diagnostic sensitivity and specificity in human beings for the differentiation of early ureteral obstruction from other causes of renal pain.30,31 Resistive index has been evaluated in sedated normal dogs and cats32,33 and in a small number of dogs and cats with obstructive and nonobstructive renal disease.34 In this initial study of diseased animals, increase in resistive index was not a reliable sole determinant of the presence of obstructive renal disease, but the number of subjects was very small.28 Increased familiarity with this technique and with its utility as an adjunctive diagnostic modality may permit more accurate, early, noninvasive identification of AUO.

Precise localization of the site of ureteral obstruction before surgery usually requires contrast radiography or computed tomography (CT); the percutaneous antegrade pyelogram provides rapid, cost-effective presurgical localizing information.4,8 This study, performed under heavy sedation or general anesthesia, entails insertion of a long needle (e.g., 25-gauge to 22-gauge, ½-inch to 3½-inch spinal needle) perpendicular to the renal capsule and into the dilated renal pelvis with ultrasound guidance. A small-volume T-port adaptor with a 6-ml syringe attached is connected to the spinal needle, and urine is withdrawn slowly from the renal pelvis until it is half to completely empty. Depending on degree of pelvic distension, less than 1 ml or more than 5 ml may be aspirated. Urine aspirated should be submitted for cytological analysis and bacterial culture. The syringe and T-port then are disconnected carefully from the spinal needle (which is held in place firmly by the operator) and replaced with another syringe and T-port, prefilled with a sterile, iodinated contrast medium such as diatrizoate (Renografin, Squibb, Princeton, NJ) or iopamidol (Isovue, Squibb, Princeton, NJ). A volume of contrast agent approximately equal to the volume of urine removed is injected slowly into the renal pelvis, until the operator feels a subjective increase in resistance. The emptying and filling processes may be monitored sonographically. When the filling is complete, the needle is removed carefully from the kidney, and serial lateral and ventrodorsal projection radiographs are performed (e.g., at 0, 5, 15, and 30 minutes). The degree of renal pelvic dilation usually is readily apparent, as is the site of ureteral obstruction (Figures 41-7 and 41-8). Leakage of contrast from the renal pelvis into the abdomen obscures visualization occasionally.8

Percutaneous antegrade pyelography also can diagnose AUO definitively in cats with mild to moderate upper tract dilation, although the smaller the renal pelvic dilation, the greater the operator skill required to perform the study safely. Other authors have pointed out the loss of antegrade pressure and potential drawbacks of antegrade pyelography when medical management of ureteral obstruction is anticipated (see Chapter 43).

Excretory urography (EU) is of limited diagnostic benefit in ureteral obstruction. Because of the significantly decreased renal blood flow, reduced or absent glomerular filtration, and high pressure within the affected renal pelvis, concentration of contrast material and resulting opacification of the obstructed kidney and ureter are compromised. Studies in obstructed individuals may not have sufficient diagnostic value when planning appropriate intervention. Additionally, caution should be exercised in the administration of intravenous contrast materials to patients with preexisting renal compromise. Although the frequency of adverse effects is unknown in veterinary species, ample human data document a high risk of intravenous contrast-induced acute renal failure in patients with underlying chronic nephropathy.35,36 When percutaneous antegrade pyelography is not available, however, EU may provide adequate presurgical localizing information and may be of more benefit than risk.

Helical computed tomography (CT) is the imaging diagnostic test of choice in many human hospitals for localizing ureterolithiasis and also is a very sensitive method of loca-lizing mineralized obstructions in feline ureters.5 In one prospective human study comparing helical CT and resistive index, sensitivity and specificity of helical CT and resistive index measurement were high for differentiation of obstructive nephropathy, with no statistical difference found between the diagnostic abilities of the two modalities.30 Diagnostic sensitivity of CT for nonmineralized ureteral obstructions in cats may be enhanced by performing excretory CT with intravenous iodinated contrast material.5

During administration of intravenous contrast material to a patient with renal compromise, adequate hydration is paramount.37 Previous investigations have suggested that the risk of inducing contrast nephropathy in human patients with preexisting renal disease could be mitigated by administration of drugs, including mannitol, theophylline, calcium-channel blockers, diuretics, fenoldopam, or dopamine.37-42 The most recent analyses, however, have failed to identify any pharmacological manipulation superior to simple hydration in reduction of the risk of contrast nephropathy in at-risk populations.37

NEMATODES

Nematodes are tubular worms and are round in cross section and thus called round worms. They are parasites of all groups of reptiles. Adults live in tubular organs such as the gut, free in the body cavity, in the lungs and nasal passages, and subcutaneously in their reptilian hosts (see Figure 15-31). They may have either direct or indirect life cycles. They have separate sexes and complete digestive systems.

Some are pathogenic, and some may be beneficial. The effects of most nematodes are unknown, and many could be neutral in their influence on their hosts. Nematodes are the most diverse group of helminths that infect reptiles. Some produce eggs, some release L1 larvae, and some produce microfilariae that are actually motile embryos. Those that produce eggs are diagnosed with fecal flotation, and those that release larvae are easily diagnosed with a Baermann funnel. These larvae do float but are greatly distorted by the flotation medium. Those nematodes that produce microfilariae can be detected with a finding of microfilariae in the blood. Members of the Rhabditida, Strongylida, Spirurida, Ascarida, and Oxyurida, and superfamilies Trichuroidea and Filarioidea will be discussed.

What is Ureterorenoscopy?

Which procedure is a radiological examination of the bladder and urethra performed before during and after urination using a contrast medium to enhance imaging?

What is a Nephroscope used for?

Which procedure involves examination of the ureters and the renal pelvis is quizlet?