Congenital/Hereditary Diseases

Anomalies of Number and Size

1. Unilateral Renal Agenesis
2. Supernumerary Kidney
3. Hypoplasia
4. Hyperplasia
5. Compensatory Hypertrophy

Unilateral Renal Agenesis:

• Solitary Kidney
• Before diagnosis, must exclude a nonfunctioning diseased kidney or a prior nephrectomy
• Results from failure of the embryonic renal bud or renal vascular system to form
• True renal agenesis - ureter and corresponding half of trigone are missing
• Solitary kidneys are larger than expected, reflecting compensatory hypertrophy
• bilateral agenesis- usually incompatible with life

Supernumerary Kidney:

• 3rd kidney
• usually small
• possesses a separate pelvis, ureter, and blood supply
• functions normally, leads to secondary infections that may require removal

Hypoplastic Kidney (Hypoplasia):

• miniature replica of a normal kidney
• Hyperplasia- overdeveloped kidney

Compensatory Hypertrophy:

• when one kidney is forced to perform the function normally carried out by two kidneys
• result of: renal agenesis, hypoplasia, atrophy, or nephrectomy
• greatest in children and diminishes in adulthood

Anomalies of Rotation, Position, and Fusion

1. Malrotation
2. Ectopic kidney
3. Pelvic kidney
4. Intrathoracic kidney
5. Crossed ectopia
6. Horshoe kidney
7. Complete fusion
   

1. malrotation of one or both kidneys produces an appearance of the renal parenchyma, calyces, & pelvis that suggest a pathologic condition when there is none
2. abnormally positioned kidneys
3. kidneys located in the true pelvis (most common); Nephroptosis/prolapse kidney- different from pelvic kidney b/c of short ureters
4. kidneys located above the diaphragm
5. ectopic kidney lies on the same side as the normal one and is commonly fused
6. most common fusion type; both kidneys malrotated; lower poles are fused; renal function not impaired
7. single irregular mass (disk, cake, lump, & doughnut kidney)

• duplex kidney
• most frequent congenital anomalies of the urinary tract that can be seen in many variations: simple bifid pelvis to a completely double pelvis, double ureter, and double ureterovesical orifice

• cystic dilation of the distal ureter near its insertion into the bladder
• ectopic ureteroceles are found almost exclusively in infants and children, most are associated with ureteral duplication
• Rad appearance: if filled, lesion appears as a round/oval density surrounded by a thin radiolucent halo representing the wall of the prolapsed ureter and the mucosa of the bladder (Cobra head sign)
• if not filled, appears as a radiolucent mass w/in the opacified bladder in the region of the ureteral orifice
• children w/ ureteral duplication have an 80% incidence
• excretory urography- large, eccentric filling defect impressing the floor of the bladder

• found exclusively in males
• causes bladder outlet obstruction
• leads to severe hydronephrosis, hydroureter, & renal damage
• thin transverse membranes work as a reverse valve; catheterization is normal but valve prevents antegrade flow
• best demonstrated on a VCUG- stricture of the urethra and a thin radiolucency representing the membrane
• surgical intervention required to correct urine flow

• nonsuppurative inflammatory process involving the tufts of the capillaries (glomeruli) that filter the blood w/in the kidney
• represents an antigen-antibody reaction several weeks after an acute upper respiratory or middle ear infection w/ certain strains of hemolytic streptococci
• caused by chronic autoimmune disorder
• extremely permeable, allowing albumin and RBC's to leak into the urine (proteinuria or hematuria)
• dec. glomerular filtration rate causes oliguria (smaller than normal amt of urine)
• Rad appearance: increase in size
• chronic glomerulonephritis produces bilateral small kidneys

• most important inflammatory renal disease
• usually a result of E. coli entering thru bladder & ureters
• supparative inflammation of the kidney and renal pelvis caused by pyogenic bacteria (pus)
• affects the interstitial tissue between the tubules
• may spread from the bloodstream or lymphatics; originates in the bladder and ascends thru the ureters to the kidneys
• often occurs in women and children
• develops from urinary tract obstructions; leads to stagnation of urine, infection, dysuria, pyuria
• instrumentation and catheterization of the ureter play a big role in development

Rad Appearance:

• excretory urography is normal in pt.'s with this disease
• linear striation in the renal pelvis (mucosal edema)
• urography- patchy calyceal clubbing with overlying parenchymal scarring (chronic pyelonephritis)
• the cortical depression lies directly over a calyx rather than between calyces as in lobar infarctions or congenital lobulation
• percutaneous nephrostomy drain placement may be considered in some cases as an alternative to surgery

• severe form of acute parenchymal and perirenal infection with gas-forming bacteria that occurs virtually only in diabetic patients and causes an acute necrosis of the entire kidney
• presence of radiolucent gas shadows within and around the kidney is pathognomic
• affected region appears as mottled areas of low attenuation
• 60% mortatlity rate if gas pattern is present
• antibiotics (fatal if only treatment) and drainage is necessary
• nephrectomy can lower rate to 20%

• hematogenous spread of TB can lead to development of small granulomas scattered in the cortical portions of the kidneys
• renal TB usually occurs as a secondary infection from lung involvement
• typically manifest 5-10 years following primary infection
• causes ulcerative, destructive process in tips of papillae with irregularity and enlargement of calyces
• fibrosis & scarring lead to cortical scarring and parenchymal atrophy
• flects of calcification may develop in multiple TB granulomas

Rad appearance:

• spread of infection to renal pyramids causes an ulcerative, destructive process in the tips of the papillae with irregularity and enlargement of the calyces
• fibrosis and stricture formation lead to cortical scarring and parenchymal atrophy
• flecks of calcification may develop in multiple tuberculous granulomas
• eventually, the entire nonfunctioning renal parenchyma may be replaced by massive calcification (autonephrectomy)
• as the disease heals, there are multiple areas which the ureteral strictures alternate with dilated segments, producing a beaded/corkscrew appearance
• in advanced cases, the wall of the ureter may become thickened and fixed with no peristalsis; results in a pipestem ureter that runs directly to the bladder

• destructive process involving a varying amount of the medullary papillae and the terminal portion of the renal pyramids
• if a piece of medullary tissue is completely separated for the rest of the renal parenchyma, an excretory urogram shows a characterisitc ring of contrast material surrounding a triangular lucent filling defect representing the sloughed necrotic tissue
• the remaining calyx has a round, saccular, or club-shaped configuration
• ureteral tamponade placement can control papillary bleeding caused by separation

• inflammation of the urinary bladder
• most common in women b/c of their short urethra
• major cause is spread of bacteria present in fecal material
• instrumentation and catheterization can also be the cause (nosocomial infection)

Rad appearance:

• chronic cystitis causes a decrease in bladder size that's often associated with irregularity of the bladder wall
• in candidal cystitis, fungus balls may produce lucent filling defects in the opacified bladder
• emphysematous cystitis - inflammatory disease of the bladder that most often occurs in diabetic patients and is caused by gas-forming bacteria
• plain films show a ring of lucent gas outlining all or part of the bladder wall and the presence of gas within the bladder lumen

• most commonly formed in the kidney
• asymptomatic until lodged in the ureter and cause partial obstruction
• result of underlying metabolic abnormality: hypercalcemia, or any cause of increased calcium excretion in the urine
• two major complications: Renal colic- severe pain due to an obstructing or traveling stone; Obstruction- renal pelvis dilates (hydronephrosis)
• 80% of symptomatic renal stones contain enough calcium to be radiopaque and detectable on plain KUBs
• plain KUBs miss 34% of stones b/c of size and/or location, or because they're obscurred by bowel or bone
• non-contrast helical CT is best; 95% more accurate than excretory urography
• CT demonstrates the hydroureter or hydronephrosis that results from the obstruction, and density readings help determine the type of stone
• in ultrasound, stones smaller than 3mm may not produce a detectable acoustic shadow
• excretory urography is used to detect these invisible, nonopaque stones that appear as filling defects in the contrast-filled collecting system

Kidney Stones

(Location & Treatment)

• at times, a stone may completely fill the renal pelvis (staghorn calculus), blocking the flow of urine, common w/ bacterial infections
• nephrocalcinosis-calcium deposited in the renal parenchyma
• renal tubular acidosis-a disorder in which the kidney is unable to excrete an acid urine
• ureteral calculi-oval with long axes paralleling the course of the ureter; situated medially above the interspinous line
• phleboliths-spherical, located in the lateral portion of the pelvis below a line joining the ischial spines
• unusual type of stone - hard burr (jackstone); many irregular prongs that project from its surface
• Upper ureter procedures (above the pelvic brim)
  
  • chemolysis- percutaneous catheter used to dissolve large kidney stones into smaller pieces that pass easily
  • lithotripsy- breaks up the stone using an external source of shock waves that shatter the hard stone into sand-sized particles which are then excreted in the urine
• Lower ureter procedures (in the pelvis)
  • cystoscopic retrieval- ureteroscopy basket
  • laser destruction

• major causes in adults: urinary calculi, pelvic tumors, urethral strictures, and enlargement of the prostate gland
• major causes of mechanical obstruction in children: congenital malformations such as ureteropelvic junction narrowing, ureterocele, retrocaval ureter, posterior urethral valve
• blockage above the level of the bladder causes unilateral dilation of the ureter (hydroureter) and dilation of renal pelvicalyceal system (hydronephrosis)
• bilateral hydronephrosis- indicates obstruction at the base of the bladder or urethra
• IVU- demonstrates dense nephrogram, delayed or decreased pelvicalyceal filling due to dilation and elevated pressure in the collecting system
• study may be prolonged for up to 48 hrs to determine precise site
• acute unilateral obstruction- ureteral stone; opacification of the gallbladder 8-24 hrs after injection of contrast
• antegrade pyelography- catheter/needle is placed percutaneously into the dilated collecting system under US or fluoro; then contrast is introduced

• most common unifocal masses of the kidney
• usually in the cortex of the lower pole
• fluid filled, usually unilocular; septa sometimes divide the cysts into chambers which may or may not communicate with each other
• thin curvilinear calcifications can be demonstrated in the wall of about 3% of simple cysts
• cortical margin appears on nephrotomography as a very thin, smooth, radiopaque rim about the bulging lucent cyst (beak sign)
• thickening of the rim about a lucent mass is suggestive of bleeding into a cyst, cyst infection, or a malignant lesion
• cause a focal displacement of adjacent portions of the pelvicalyceal system

• congenital disorder in which multiple cysts of varying size cause lobulated enlargement of the kidneys and progressive renal impairment, which results from cystic compression of nephrons, which causes localized intrarenal obstruction
• present in adults in their 30's
• 1/3 of pts have associated cysts of the liver
• 10% have one or more saccular (berry) aneurysms of cerebral arteries, which may rupture and produce a fatal subarachnoid hemorrhage
• most important anomaly of the kidney
• Rad appearance:
• US will confirm; skip IVP
• excretory urography demonstrates enlarged kidneys with a multilobulated contour; poorly visualized outlines
• the nephrogram has a distinctive mottled or Swiss cheese pattern caused by the presence of innumerable lucent cysts of varying size throughout the kidneys
• Treatment:
• no cure available; meds are prescribed to control pain, high blood pressure,and infection related to the disease
• renal failure requires dialysis, and renal transplantation may be considered
• infantile polycystic kidney- ages 3-5; newborns: fatal if bilateral; unilateral: hepatosplenomegaly, portal hypertension, & esophageal varices included

• hypernephroma- most common renal neoplasm; others include: adenocarcinoma & Grawitz tumor
• 90% are malignant
• mainly in pts 40+ yrs with painless hematuria
• tumor originates in the tubular epithelium of the renal cortex (renal tubules) & spreads to bone and lungs
• 10% of hypernephromas involve calcification, located in reactive fibrous zones about areas of tumor necrosis
• the location of calcium within the mass is more important than the pattern of calcfication
• triad of symptoms: hematuria, flank pain, and a palpable mass

Rad appearance:

• initially causes elongation of adjacent calyces; progressive enlargement and infiltration lead to distortion, narrowing, or obliteration of part or all of the collecting system
• CT is most accurate method for detecting enlargement or paraaortic, paracaval, and retrocrural lymph nodes and spread to the ipsilateral renal vein and inferior vena cava
• nephrectomy is the most common treatment
• radiofrequency ablation is suggested for pts with bilateral lesions and those at high surgical risk

• most commmon malignant neoplasm of children under 5; 2nd most common of entire children population
• lesion arises from embryonic renal tissue, may be bilateral, tends to become very large and appear as a palpable mass that displaces kidney
• highly malignant
• must be differentiated from neuroblastoma- a tumor of adrenal medullary origin that is the second most common malignancy in children
• peripheral cystic calcification occurs in 10% of Wilms' tumors in contrast to the fine, granular, or stippled calcification seen in half of the cases of neuroblastoma

Rad appearance:

• excretory urography- the intrarenal Wilms' tumor causes pronounced distortion and displacement of the pelvicalyceal system
• the major effect of the extrarenal neuroblastoma is to displace the entire kidney downward and laterally
• if treated early, there's a 50% survival rate or else prognosis is poor

• most commonly originates in the epithelium and is called urothelial carcinoma (transitional cell carcinoma)
• usually seen in men 50+; 4th most common cancer in men
• related to smoking: carcinogenic metabolites excreted in urine
• Egypt, most likely related to the high prevalence of the parasitic infection schistosomiasis in that country
• may produce fingerlike projections into the lumen or it may infiltrate the bladder wall
• more invasive tumors require removal of the entire bladder with transplantation of the ureters into a loop of ileum
• KUB: punctuate, coarse, or linear calcification
• IVU: polypoid defects with wall thickening
• CT: mass projecting into bladder lumen
• MRI: predicts depth of wall invasion

• occurs most frequently in children who are severely dehydrated
• may be unilateral or bilateral
• influenced by the rapidity with which venous occlusion occurs
• sudden total occlusion causes striking kidney enlargement with minimal or no opacification
• venous occlusion is partial or accompanied by adequate collateral formation, the kidney enlarges and appears smooth
• anticoagulants are generally given to prevent new clots from forming

• rapid deterioration in kidney function that is sufficient to result in the accumulation of nitrogen containing wastes in the blood/odor of ammonia on the breath
• prerenal failure: dec. blood flow to the kidneys caused by low blood volume (hemorrhage, dehydration, or surgical shock), cardiac failure, or obstruction of both renal arteries
• postrenal failure is caused by obstruction of the urine outflow from both kidneys, most commonly a result of prostatic disease or functional obstruction of the bladder neck
• urine output may dec. to less than 40 ml per 24 hour period (oliguria)
• US can assess renal size, ID renal parenchymal disease, and exclude hydronephrosis
• diuretics used to inc. urine flow and vasodilators to inc. renal blood flow

• chronic kidney dysfunction may reflect personal, postrenal, or intrinsic kidney disease
• underlying causes of chronic renal failure include bilateral renal artery stenosis, bilateral uretral obstruction, and intrinsic renal disorders such as chronic glomerulonephritis, pyelonephritis, and familial cystic diseases
• failure to clear nitrogen-containing wastes adequately from the circulation leads to the accumulation of excessive blood levels of urea and creatinine in the blood (uremia)
• a decrease in ability of the kidney to synthesize erythropoietin, which helps regulate the production of red blood cells, leads to the development of anemia
• in the skin, uremia causes intense itching (pruritus) and a sallow (yellowish) coloring resulting from the combined effects of anemia and retention of a variety of pigmented metabolites (urochromes)
• a reduction of serum calcium can produce the muscle twitching commonly seen in uremic pts
• plain abdominal image demonstrates bilateral renal calcifications (nephrocalcinosis) or obstructing ureteral stones
• antihypertensive drugs slow the nephron loss and minimize complications
• kidney transplant may be suggested

• nephrons- filter waste products from the blood, reabsorb water and nutrients from the tubular fluid, and secrete excess substances in the form of urine; filters about 190L of water out of glomerular blood each day
• glomerulus- urine forms here; tuft of capillaries with very thin walls and a large surface area
• Bowman's capsule- surrounds glomerulus
• proximal convoluted tubule- urine proceeds into here; large amt of water & nutrients are reabsorbed into the blood capillaries surrounding the tubules
• 2 hormones that influence: ADH antidiuretic hormone (secreted by posterior pituitary gland) & aldosterone (secreted by adrenal glands)
• loop of henle- complex structure of a descending limb, loop, and ascending limb that reabsorbs salt & water
• distal convoluted tubules- permit the excretion of concentrated urine; maintains electrolyte balance & acid base balance
• collecting tubules- openings in the papillae for urine to pass into the calyces and on to the funnel-shaped renal pelvis and tubular ureters
• vesicoureteral reflux- back flow of urine into the ureters during bladder contraction
• trigone- triangle shaped floor where the openings of the two ureters lie at the posterior corners
• bladder holds up to 250 ml

1. Vesicoureteral Reflux
2. Hypospadias
3. Epispadias

1. backflow of urine from bladder into ureters

- due to muscular origins; inflammation of bladder

- infection also occurs

- common in boys & girls 3-7 yrs old

- frequent UTI

- VCUG used to determine degree of reflux

2. abnormally placed urinary meatus below tip of penis

- common birth abnormality of genitalia in male infants

- due to widened pubic bone

3. abnormal opening above tip of penis

- due to widened pubic bone

1. oliguria
2. polyuria
3. anuria
4. retention
5. hematuria
6. uremia
7. cystitis
8. pyelitis
9. nephrostomy
10. ureteral stent

1. decrease in urine output
2. increase in urine output
3. no urine production
4. bladder does not release urine
5. blood in the urine
6. toxic wastes in the blood
7. inflammation of the bladder
8. inflammation of the renal pelvis
9. opening of kidney for drainage
10. thin, flexible tube threaded into the ureter