Renal and Urinary Tract Disorders in Children
Development Malformation in the Lower Urinary Tract
Duplication of the renal pelvis and ureter
- common
- 80% are unilateral
- May be asymptomatic
- May result in (if there is obstruction to the lumen of the duplication)
1) hydroureter
2) hydronephrosis
3) susceptibility to infection (pyelonephritis)
Ureteral Valves
- unknown developmental basis
- could represent defective innervation with local inability to maintain ureteral peristalsis
- ureteropelvic obstruction may present at birth with giant hydronephrosis
Vesicoureteral Reflux
- common and serious anomaly
- can be due to the size of the ureter – vesicle orifice
- can be due to ureter to vesicle insertion point location
Diverticulum
- can be in the ureter and urinary bladder
- due to weakening of the wall
- congenital and acquired
Exstrophy of the bladder
- defect results from failure of formation of the ventral bladder wall and abdominal wall
- occurs in 1/30000 births
- males>females
- accompanied by diastases of the pubic symphysis, defect in the lower wall, and epispadias
Posterior urethral valves
- the valves serve as a one way obstruction
- urine has a hard time flowing distally
- probe can be passed proximally
- Presents
1) dilatation and hypertrophy of the bladder
2) bilateral hydroureter
3) hydronephrosis
- Can be so complete (obstruction) that oligohydramnios and pulmonary hypoplasia occurs
- Disease of males
Classification of renal developmental malformations
Renal Agenesis
- Unilateral
Ø Asymptomatic, compatible with longevity
Ø Other kidney compensates by undergoing hypertrophy
- Bilateral: Potter’s Syndrome
Ø compatible with intra- , but not extrauterine life
Ø Features
1) characteristic facies: wide set eyes, beak nose, micrognathia, low set ears
2) oligohydramnios
3) amnion nodosum
4) pulmonary hypoplasia
5) malformed lower extremities
Renal Hypoplasia
- most small kidneys are atrophic due to infection, not hypoplastic
- Oligomeganephronia (Doll’s Kidney)
Ø Kidney with reduced number of pyramids from the normal 10-14
Ø Residual glomeruli are hyperplastic
Anomalies of renal differentiation
- Dysplasia (Cystic renal dysplasia)
Ø THE MOST COMMON FORM OF CYSTIC DISEASE IN CHILDHOOD
Ø Only a disease of children
Ø Due to a failure of differentiation of the nephrogenic mesenchyme
Ø Distribution
1) bilateral: dysplasia is incompatible with extrauterine life
2) unilateral: may be asymptomatic (except for cyst)
3) Segmental: a protion of one or both kidneys
4) Focal: microscopic appearance in one or both kidneys
Ø Pathology
- GROSS
1) irregular contour w/o the usual reniform pattern
- MICRO
1) Immature ducts
2) No normal configuration
3) Primitive tubules
4) Non-inflammatory
5) Islands of cartilage and bone
- Polycystic Disease
Ø congenital
Ø kidney is replaced by numerous cysts
Ø two types
1) ADULT TYPE – autosomal dominant polycystic kidney disease
- Clinical
1. 6% of patients requiring dialysis or transplant (COMMON)
2. manifest in 4th decade
3. Symptoms: hematuria, pain, renal failure
4. Can rarely occur in childhood
- Morphology
1) large kidneys w/ numerous cysts
2) atrophy and infection of the parenchyma
3) associated manifestations: cysts in other organs, cerebral artery aneurysms, coarctation of the aorta
2) INFANTILE TYPE – autosomal recessive polycystic kidney disease
- always bilateral and more frequently fatal early in life
- enlarged kidney with numerous small cysts everywhere
- the cysts are actually dilated tubules (collecting ducts)
- Severe liver disease
- Medullary Cystic Disease
Ø Two types
1) NON-UREMIC medullary cystic disease (sponge kidney)
a. medulla cystic dilatations – composed of the collecting ducts
b. usually bilateral
c. adults
d. normal renal function
e. calculi are common
2) UREMIC medullary cystic disease (uremic sponze kidney)
a. uremia = azotemia
b. childhood onset usually
c. progressive renal failure
d. Symptoms: polyuria, polydipsia, tubular acidosis, renal failure
e. Morphology: cysts at corticomedullary junction
f. BAD PROGNOSIS
- Simple Cysts
Ø increasing frequency with age
Ø rare in children
- Acquired Cystic Disease (Dialysis associated)
Ø kidneys with end stage renal disease and prolonged dialysis which develop numerous cortical and medullary cysts
Ø disease of adults
Ø adenomas and rarely carcinomas may be present
- Microcystic disease with nephrotic syndrome
Tags: amnion nodosum, bilateral hydroureter, Diverticulum, Exstrophy, hydronephrosis, hydroureter, Medullary Cystic Disease, oligohydramnios, Polycystic Disease, potter's syndrome, pulmonary hypoplasia, Pyelonephritis, Renal Agenesis, Renal Hypoplasia, ureter, Ureteral Valves, Vesicoureteral Reflux
