Kidney, Ureter, Bladder

KIDNEY URETER BLADDER

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KUB is variously called a plain film or scout film. It is done primarily to IVP Difference in x-ray attenuation between the kidneys and the enveloping perineal fat in plain films provides a crude index of renal anatomy and pathologic changes. Preliminary to IVP Since IV contrast can hide the calculi (same x-ray density as contrast) it serves as the film oft reference for all subsequent films done after injection of contrast material. Good to pick up calcifications. Observe for calcifications over kidney, ureters, bladder regions and rest of the abdomen Can identify distended bladder Can identify abdominal and pelvic masses. Observe renal outline for size and mass density. Incidental non diagnostic findings on KUB may alert the physician to the possibility of urinary tract injury In trauma fracture of vertebrae, ribs or pelvis alerts you to GU tract injury Psoas obliteration and concavity of spine towards the side of pathology Abnormal air collections suggestions of renal or peri-renal abscess

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Sharp and pointed Dark area around collecting system duct to fat in hilum Course or ureters Anterior to psoas at L4-L5

Scout Film 

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Any calcification over kidney, ureters, bladder regions and the rest of the abdomen Skeleton Spine Transverse processes Pelvis Soft Tissue o Psoas shadows o Margins of kidneys o Bladder distention

Nephrogram Phase       

Kidney Size 11-13cm Shape: bean shaped Contour: smooth Thickness of cortex: uniform Axis: tilted Superior pole closer to mid line

Collecting System 

Calyces

Bladder   

Size Displacement and extrinsic pressure Lumen for filling defects

Limitations

Disadvantages 

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Labor and time intensive – it may take up to 6 hours to complete in the severe obstruction It requires placement of an intravenous line Requires a bowel preparation for optimal results Involves intravenous injection of potentially allergic and mildly nephrotoxic contrast

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Utility/Indications  

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Retrograde Pyelogram

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Like IVP, retrograde pyelography relies on contrast medium to produce detailed x-ray images of the urinary tract

Images of the urinary tract Indications 

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Commonly performed when IVP produces an inadequate picture. Useful to study urinary tract obstruction when further calcification of nature of utreteral obstruction is required It also complements cytoscopy while investigating a patient with hematuria or recurrent or suspected cancer Detects small lesions in the collecting system. E.g. transitional cell carcinoma

Contrast complications May aggravate an existing urinary tract infection or triggering one from the catheterization

Children with urinary tract infections Reflux is detected if contrast is seen to flow in retrograde fashion up the ureters from the bladder Pelvic trauma where rupture of the bladder or urethra is suspected o If the bladder is ruptured, extravasations of contrast will be seen outside the bladder in the pelvis or abdomen o If urethra is ruptured, there is extravasations into the perineum

How it is done…     

Avoiding cystourethrogam is performed by inserting a catheter into the urethra Contrast material is then instilled into the bladder through the catheter x-rays are taken before, during and after filling of the bladder when the bladder is full, the catheter is removed while the patient voids, additional x-rays are taken

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Hematuria Local staging of cancer to allow definitive surgical management if needed Renal artery and vein evaluation

Disadvantages • • • • Limitations  

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Requires placement of an IV line for IV contrast Exposes patient to radiation Contrast toxicity or allergy Most yong children require sedation to undergo a CT scan CT scans are relatively expensive

Insertion of the catheter is painful While conventional voiding cystogrms are still necessary to evaluate the male urethra for posterior valves and bladder trauma, the majority of studies today re done effectively with radionuclide cystograhy Images

Utility      

Helpful in defining renal, bladder and prostate anatomy It is the test of choice to exclude urinary tract obstruction US can, in the majority of cases diagnose hydronephrosis Good for evaluating kidney size Good to distinguish between cysts and solid mass Good to localize kidney for biopsy

Indication • • •

Ultra fast CT is considered preferable to KUB for detection of suspected stones If ultrasound evaluation is equivocal for a cyst, or is suggestive of malignancy In evaluating solid abdominal masses

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MRI is as good as CT or better in characterizing lesions of kidney and prostate Because of its ability to show soft tissue sin exquisite detail, MRI can detect disease and evaluate renal vasculature and inferior vena cava MRI can delineate a cyst from a solid mass It can identify the spread of kidney cancer into the renal vein, IVC and prerenal area (staging)

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Disadvantages • • •

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Expensive Limited availability MRI has limited applicability for urinary tract since the non-specificity of its signals makes it ineffective in detecting calcifications and bladder abnormalities Patients with pacemakers, aneurysm clips, ear implants, and metallic pieces in vital body locations cannot be imaged safely.

occur in approximately 1 in every 4000 children females are affected 4-7 times more often than males

Radiographic findings  a classic appearance known as the “cobra head deformity” and resembles a snake’s head bulging into the bladder  often best detected on IVP Case 2

Normal IVP Case 3

Renal Agenesis

Case 1

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Ureterocele  

congenital saccular dilatation of the terminal portion of the ureter ectopic ureterocele enter the bladder, typically arise from the upper pole moiety of a duplicated collecting system

when the ureteric bud fails to reach the metanephric blastema, there is no induction of nephron development associated ipsilateral abnormalities are almost always present ans include absence of ureter, hemitrigone, or vas deferens, seminal vesicle cyst, or Muellerian abnormalities such as unicornate uterus absence of the ipsilateral adrenal gland is seen in 10 % of these patients incidence of renal agenesis is one per 1000 live births, 75 % of which are male

Bilateral Renal Agenesis a fatal anomaly occurs in one per 3000 live births, and due to oligohydramnios -these newborns present with Potter’s syndrome-low set ears, broad flat nose,  

prominent skin folds below the lower eyelids, pulmonary hypoplasia and pneumothorax Case 4

Horseshoe Kidney  occurs in one of every 400 livebirths Multicystic Dysplastic Kidney (MCDK) 

occurs as a result of inadequate induction of maturation of the metanephric blastema by the ureteric bud

2 Types a. Pelvoinfundibular MCDK- randomly distributed, non-communicating cysts replace normal renal parenchyma, the kidney is not functional and an atretic ureter is often present b. Hydronephrotic MCDK- representing a severe inutero form of UPJ obstruction 

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both forms present with an abdominal mass detected during infancy and are associated with contralateral UPJ obstruction UPJ obstruction with associated hydronephrosis is the most common palpable abdominal mass in newborns

Medullary Sponge Kidney 

Case 5

also known as benign renal tubular ectasia, it is a cystic dilatation of the collecting tubules in 1 or more renal pyramid. Urine stasis in the collecting tubules may lead to stone formation within the ectatic tubules

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Pelvic Kidney

premature arrest of cranial ascent of the kidney  a 3:2 male-to-female predominance  bilateral pelvic kidneys may fuse, forming a discoid single kidney known as a pancake kidney  major complications include: -trauma (due to decreased protection) and nephrolithiasis (due to altered geometry resulting in urine stasis)  associated with other urinary tract anomalies including: -UPJ obstruction, vesicoureteral reflux, and decreased function 

Case 1

Case 6

most common renal anomaly males are twice as likely to have the anomaly as females associations include UPJ obstruction, duplication anomalies and stone formation due to abnormal kidney geometry and urine stasis

density cysts (>20 HU), nonenhancing M ultiloculated, hemorrhagic, dense calcifications, nonenhancing solid component Marginal irregularity, enhancing solid component

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Renal-sparing suregery

Radical nephrectomy

Bosniak I Lesions  simple fluid with imperceptibly thin walls and no septations, calcifications, or enhancement  on CT, simple fluid possesses an attenuation at or around 0 HU Bosniak II Cyst

Renal Cysts  

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50 % of the population older than 50 years most are asymptomatic, though a large cyst can cause discomfort and hypertension a ruptured cysts may result in hematuria, an infected cyst results in fever both infected cysts and hemorrhagic cysts are non-simple by imaging

Bosniak Classification of Renal Cysts by CT Classification I II

Features Simple Cyst Septated, minimal calcium described as “egg shell” thin, high-

Managament Non-operative Non-operative

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the cyst shows high signal on T1 and T2weighted images suggesting it is more complex perhaps from hemorrhage or from proteinaceous contents

Bosniak II Lesions

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may demonstrate wall or septal thickening, bulky calcifications, or septal enhancement unenhanced CT demonstrates a lobulated cystic lesion with an irregularly calcified septum and the hint of other septa

Bosniak IV Cyst

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contain hair-thin septations, faint calcifications, and/or non-simple fluis no contrast enhancement should present CT demonstrates a faint calcification (blue arrow) ultrasound clearly depicts the septum

Bosniak III Cyst

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T2 weighted axial MRI images shows a septated mass the mass is predominantly cystic (contains high signal fluid on T2 weighted images) these septations (arrows) showed minimal enhancement on the gadolinium enhanced portion of the MRI study consistent these lesions are usually removed because of a high likelihood of malignancy

Bosniak III Lesions

shows a markedly complex cystic renal mass (red arrows) enhancement of a solid portion within the mass (yellow arrow) seen on the gadolinium enhanced images confirms this is quite likely to be a cystic renal cell carcinoma this lesion was surgically removed

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Autosomal Dominant Polycystic Kidney Disease (ADPKD)   

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an autosomal dominant disease a prevalence of 0.1 % accounting for 10 % of patients on chronic dialysis patients have multiple kidney cysts leading to enlarged palpable kidneys the disease progresses slowly, eventually resulting in end-stage renal disease and the need for dialysis or transplant

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the classic triad of hematuria, flank pain, and a palpable abdominal amss occurs in ~10 % and indicates advanced disease 30 % of patients present with metastatic disease with predilection for lung, soft tissue, bone, and liver risk factors include smoking, obesity, male (2:1), phanacetin, and other analgesics, von Hippel-Lindau disease, chronic dialysis, family history CT: enhancing mass (does not enhance as intensely as normal parenchyma) with distortion of parenchyma, collecting system and contour abnormalities, calcifications in 10 %, presence of filling defects in collecting system, renal veins and IVC US: small tumors are generally hypoechoic, large tumors hyperechoic

Case 3

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55 y/o male presented with palpable mass in the right flank with pain and hematuria

Renal Cell Carcinoma 

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also known as renal adenocarcinoma, hypernephroma, clear cell carcinoma, and malignant nephroma accounts for 90-95 % of primary renal cancers 50-60 years patients present with hematuria (50 %), flank pain (40 %), palpable mass (35 %), weight loss (25 %), and paraneoplastic syndrome

MRI: the axial image shows a large mass in the right kidney and the arrow points to right renal vein invasion by the tumor. Coronal MR venogram confirms tumor thrombus in the IVC (arrow) in an advanced renal cell carcinoma

Robsons Classification Stage I  (50 % 5-year survival) confined to renal parenchyma, < 7 cm Stage II  (50 %) spread outside of renal capsule, but confined by Gerota’s fascia, or >7 cm Stage III (35 %)  venous tumor extension to renal vein, infradiaphragmatic or supradiaphragmatic IVC  regional lymph node metastases

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venous extension and regional lymph node metastases IV (15 %) direct invasion beyond Gerota’s fascia distant metastases late post-nephrectomy metastases occur in 10 %

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long term survival is possible with untreated tumor

intrarenal abscess (arrows) with perinephric extension

Renal Abscess    

Angiomyolipomas

usually a complication of untreated pyelonephritis caused by ascending infection from gram negatives organisms (E. coli) predisposing factors include stone disease, diabetes, or AIDs complications include retroperitoneal spread and renocolic fistula

Case 1

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are hamartomas containing fat, smooth muscle, and blood vessels most are asymptomatic, but may hemorrhage if large larger symptomatic lesions (>4 cm) can be resected or embolized 80 % of patients with tuberous sclerosis have AML, usually multiple lesions bilaterally CT scan: fat, appearing as a hypodense US: hyperechoic MRI: hyperintense (T1 weighted MRI) mass the presence of fat is almost pathognomonic for AML calcifications are not a common finding of angiomyolipomas and would lead towards a diagnosis or renal cell carcinoma

Chronic Medical Renal Disease 

a small right kidney with uniformly thin renal cortex and marked increased cortical echogenicity all points to a chronic insult to this kidney. L= liver

Case 2

Case 5

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CECT scan through the kidneys in a patient with pyelonephritis and persistent fever despite antibodies shows left intrarenal fluid collection with areas of poor or no enhancement consistent with

Patient had fever, flank pain, costovertebral tenderness

Pyelonephritis 

a bacterial infection of the renal parenchyma and collecting system

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a clinical diagnosis based on fever, flank pain, costovertebral angle tenderness, and urinary tract infection

D2: regional lymphadenopathy (N4), distant metastases (M1)

Case 3

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IVP shows masslike filling defect outlined by excretion contrast in the bladder carcinoma. DDx- tumor, blood clot and fungus ball

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Non contrast CT scan of the pelvis shows focal infiltrative thickening of the posterolateral bladder wall (arrows)

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Contrast enhanced CT scan of the pelvis shows marked infiltrating mass thickening the bladder wall and obstructing both ureters (arrows) resulting in bilateral hydroureter and hydronephrosis

Bladder Carcinoma 90 % of bladder carcinomas are transitional cell carcinomas (TCC)  75 % of which are papillary  25 % are infiltrative  other malignant neoplasms -squamous cell carcinoma (after schistosomiasis infection) -adenocarcinoma -leiomyosarcoma -lymphoma -rhabdomyosarcoma (in ages 2-6)  benign lesions include leiomyoma, fibroepithelial polyp, hemangioma, pheochromocytoma, and adenoma 

Differential Diagnosis Focal mural filling defect in the bladder  common causes, such as neoplasm, stone, blood clot, or enlarged prostate gland; and  uncommon causes, such as focal cystitis, ureterocele, benign neoplasm, endometriosis, or fungus ball Jewett-Strong-Marshall Staging (TNM staging) 0: carcinoma-in-situ (TIS) and noninvasive papillary tumor (TA) A: papillary tumor with invasion of lamina propia (T1) B1: superficial muscle invasion (T2) B2: deep muscle invasion (T3A) C: perivesical fat invasion (T3B) D1: invasion of contiguous viscera (T4A), invasion of pelvic or abdominal wall (T4B)

Case 2

resulting in a particular type of bladder known as a “Hutch” diverticulum

Cystitis an inflammation of part or the entire urinary bladder wall  common causes include: -infection- E.coli, klebsiella, pseudomonas, schistosomiasis, also viral and fungal cause -irritative or mechanical (such as an indwelling catheter or a stone) -toxic (cyclophophamide) -radiation -allergic  CECT of the pelvis  an indwelling nephroureterical stent sits in the bladder  this patient received pelvic radiation for a non-bladder malignancy. This resulted in bladder wall thickening and obstruction of the left ureter at the ureteral orifice into the bladder causing left-sided hydronephrosis and thus requiring stenting  note bladder wall thickening in the left lateral bladder wall from radiation induced cystitis  a mass like lesion in the dependent portion of the bladder may represent a mass (arrows). However, this patient presented with gross hematuria which resolved following irrigation  differential diagnosis: bladder or prostate mass 

Bladder Diverticula

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contrast enhanced CT of pelvis shows a small diverticulum projecting from the left lateral wall of the bladder (arrow)

Cystocele

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as focal herniations of the urothelium and submucosa cystoceles usually occur in the setting of chronic elevation of intravesical pressure they tend to occur next to ureteral orifices, and occur where small outpouchings of mucosa evaginate between hypertrophied detrusor muscle bundles, but do not extend past the bladder wall cystoceles constitute an important cause of urinary stasis, ureteral obstruction, and vesicoureteral reflux

Bladder Fistulas

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ultrasound shows a large outpouching of the bladder wall and mucosa projecting from the lumen of the bladder. This diverticulum was in close proximity to the ureteral entrance into the bladder

Bladder Stones

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the most common causes of intravesical air include bladder catheterization or instrumentation vesicoenteric fistulas may be difficult to image- only 30-60 % are seen with cystography and barium enema iatrogenic causes, diverticulitis, carcinoma, and regional enteritis or Crohn’s disease may lead to vesicoenteric fistulas

plain film radiograph of the pelvis shows an air lucency in the bladder (arrows) in the same patient as above

Case 6

Emphysematous Cystitis  

a rare form of bacterial cystitis that occurs in patients with poorly controlled diabetes E. coli is the most common pathogen and urinary stasis is a common feature

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unenhanced CT scan of the pelvis in patient with hematuria shows stone material layering in the dependent portion of the bladder

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unenhanced CT scan of the pelvis (bone windows on the left and soft tissue windows on right) shows laminated stone in the dependent portion of the bladder. There are also stones in the proximal urethra (arrows)