Flashcards in L82 – Congenital and Developmental Abnormalities of the Urinary Tract Deck (88):
What are the 3 types of abnormalities in renal tissue?
Abnormalities in amount of renal tissue
Anomalies in shape and position
Abnormalities of differentiation
Name the 2 Abnormalities in amount of renal tissue?
• Agenesis (Failure to form)
• Hypoplasia (Failure to develop to normal size)
Name the 2 Abnormalities in shape and position of renal tissue?
• Horseshoe kidneys
• Ectopic kidney (abnormal position)
What is the consequence of Bilateral agenesis of renal tissue?
Decrease urine production by fetus in utero
cause significant oligohydramnios - very low amount of amniotic fluid in sac
>> Potter's sequence
Renal tissue hypoplasia is commonly bilateral or not? What is the consequence of bilateral hypoplasia?
• More commonly unilateral
• Bilateral cases usually develop renal failure in
Describe the shape of horseshoe kidney?
Kidneys too close to each other >> fuse (usually at lower
What are the common abnormal positions of ectopic kidneys? Size?
Just above pelvic brim or in pelvis
Normal or slightly small in size
What is the consequence of ectopic kidney on ureter?
• Kinking/tortuosity of ureters may lead to
obstruction -> predispose to infection
What is the main source of amniotic fluid?
Name of Reduction in amount of amniotic
Lead to Potter's sequence
Is Potter's sequence a syndrome? Define?
Cascade of anomalies triggered by one initiating aberration
How does Potter's sequence occur?
result of significant oligohydramnios of whatever cause
Name 3 causes of Potter's sequence?
• Bilateral renal agenesis
• Infantile polycystic kidney disease
• Chronic leakage of amniotic fluid etc.
What does Oligohydramnios lead to? Give 4 examples of results?
• Oligohydramnios lead to fetal compression
• Flattened facies
• Positional abnormalities of hands and feet
• Dislocation of hip
• Hypoplastic lungs (resp. failure)
What is Flattened facies seen in Potter's sequence?
compression of ears, nose;
underdevelopment of lower jaw > receding chin
Name the 2 abnormalities of differentiation and their subtypes?
• Multicystic Renal Dysplasia
• Polycystic kidney disease
>> Autosomal recessive or Dominant
Difference in onset between the 2 types of Polycystic kidney disease?
• Autosomal Recessive (Childhood)
• Autosomal Dominant (Adult)
Give the embryonic developmental abnormality for multicystic renal dysplasia?
Developmental abnormality of metanephric duct
>> resulting in aberrant
differentiation of metanephric blastemal
Is Multicystic renal dysplasia hereditary?
Sporadic disorder, NOT hereditary
Is Multicystic renal dysplasia pre-neoplastic?
What are the types/ variations of Multicystic renal dysplasia?
• Unilateral or bilateral, segmental or focal
Size and shape of affected kidneys in Multicystic renal dysplasia?
may be small or enlarged
Multiple cystic structures deform the kidney
What is associated with Multicystic renal dysplasia?
Characteristic presence of cartilage and primitive tubules
- ureteric atresia (abnormal narrowing)
- lower urinary tract obstructive lesion
What causes Childhood polycystic kidney disease?
Autosomal recessive condition, Most cases caused by mutations of PKHD1 gene
What does PKHD1 gene encode for?
What are the subcategories of Childhood polycystic kidney disease?
Perinatal, Neonatal, infantile and juvenile
Consequence of Autosomal Recessive (Childhood) Polycystic
early infantile death – Potter’s sequence
How does Autosomal Recessive (Childhood) Polycystic
Kidney Disease change kidney morphology, location?
Bilateral / symmetrical enlarged kidneys
Fusiform dilatation of collect ducts (radially arranged)
Can become large enough to push anteriorly, not retroperitoneum
Size of liver and lungs in AR Polycystic
Explain the formation of large liver in AR Polycystic Kidney Disease?
congenital hepatic fibrosis
> More prominent, thicker portal tracts, fibrotic bands extend between hepatocytes
How does congenital hepatic fibrosis lead to Portal Hypertension?
Congential hepatic fibrosis leads to abnormal proliferation of epithelium in bile duct
> Increase in portal fibrovascular tissue
> Increase connection of biliary arterial blood (high BP) with portal venous system (low BP)
What is the mode of death in AR Polycystic Kidney Disease?
neonatal renal failure >> uremia (azotemia)
Neonatal respiratory failure from small (hypoplastic) lungs
Explain the formation of hypoplastic lungs in AR polycystic kidney disease?
Big liver compresses thoracic cavity
decrease urinary output can cause oligohydramnios > compression on thoracic cavity
What is the cause of adult polycystic kidney disease?
Mutation of mostly PKD1 (ch.16), and less commonly PKD2 (ch.4)
Cysts gradually develop over time, but pathogenesis not well established
Gene frequency of adult polycystic kidney disease?
• Gene frequency about 1 in 1,000
Pathology of adult polycystic kidney disease?
Numerous cysts in cortex and medulla
>> distention causing nodular huge kidneys
Difference between the 2 types of mutations leading to adult polycystic kidney disease?
1. PKD1 (chromosome 16) = 80% cases
2. PKD2 (chromosome 4) = usually milder disease
(can be asymptomatic until old age)
Clinical presentation of Adult polycystic kidney disease at middle age?
Chronic renal failure
Gross morphology of Adult polycystic kidney disease?
Numerous cysts in cortex, medulla:
Contain urine / fluid
May be black due to hemorrhage
>> compression/ tangle with tubules
Associrated conditions of Adult polycystic kidney disease?
Berry aneurysms of cerebral arteries
Polycystic liver, lungs, pancreas
Diverticulosis of large intestines
Cardiac valve abnormalities
What are the consequences of Polycystic liver, lungs?
Liver (biliary cysts may compress on bile ducts)
Lungs (cysts may compress on airways)
What is Diverticulosis of large intestines?
herniation of mucosa out of muscular wall of
intestines (can progress into peritonitis)
What are the consequences of Berry aneurysms of cerebral arteries?
if rupture: subarachnoid hemorrhage
Increase intracranial pressure to death
What is the prenatal early diagnosis of AR polycystic kidney disease?
molecular genetic studies for PKD1, PKD2 (usually by genetic linkage studies)
What is the Teenage early diagnosis of AR polycystic kidney disease?
ultrasound (cysts may start to form)
What causes acquired cystic kidney disease?
Develops in end stage renal failure when a patient after dialysis for many years
What does acquired cystic kidney disease look like?
AR polycystic kidney disease
But these are completely different in cause
Explain how Acquired cystic kidney disease occurs?
glomerular disease = atrophy of tubules
Tubular cells may undergo hyperplastic change, forming cysts or even carcinoma
What are the 5 congenital abnormalities of the ureter>?
• Duplication (bifid ureter)
• Abnormal course, e.g. retrocaval ureter
• Ectopic opening
What is Retrocaval ureter?
When ureter wind around Inferior vena cava
>> ureter may get
obstructed easily, causing infection
How can valve defect occur in congenital ureter abnormalities?
mucosal redundance, e.g. in posterior
portion of urethra
Give an example of ectopic opening of ureter>?
open in vagina > urinary
What are the causes of extrophy of urinary bladder?
Defect of pubic symphysis/ anterior abdominal wall
Defect of bladder
Malformed external genitalia
What are the complications of chronic exposure of urinary bladder extrophy?
Adenocarcinoma arising from urachus
What are the 3 urachal anomalies?
Fistulous urinary tract
Patent urachus remains
(+umbilical urachal sinus, vesicourachal diverticulum)
How do urachal cysts form?
• Only central part of urachus persists
• Can lead to carcinoma in future
3 Congenital abnormalities of urethra in male?
What is hyposapdias?
• Abnormal urethral opening of
the ventral surface of penis
What is episapdias?
• Abnormal urethral opening on
the dorsal surface of penis
What are the 3 complications of episadias?
1) Associated with other
malformations of the urinary tract
2) Increase risk of urinary tract obstruction and ascending UTI
3) Affect normal ejaculation and insemination = subfertility
Consequences of urethral valve abnormality in urethra?
*usually in male at posterior urethra*
Dilation of proximal urethra due to constriction of urethral valve
What are the 6 common obstructive lesions/ UT obstructions?
-Renal stones (Calculi)
-Infection/ inflammation (TB kidney)
What are the variations of Urinary tract Obstruction/ Obstructive uropathy?
Acute or Insidious; Partial or Complete; Unilateral or Bilateral
What are associated complications of UT obstruction?
-Permanent renal damage, impair renal function
Acute ureteric obstruction causes___?
acute renal colic = severe pain radiates from loin at back to suprapubic region
Most common cause of acute renal colic?
Caused by acute ureteric obstruction, Commonly Renal stones
Unrelieved UT obstruction always
leads to ___ ?
damage and impairment of renal function + Infection
What are 2 outcomes that changes morphology of urinary system due to UT obstruction?
Most common site of Calculi formation? Another name for Renal stone?
Most commonly formed in Kidney
• But may form anywhere in urinary tract
How does a calculi in the kidney cause obstruction elsewhere?
dislodge and migrate to distal part of urinary tract
Age and gender most affected by Renal stones?
Men >> Women
Peak age: 20-30 years old
Name major types of renal stones?
• Calcium oxalate and phosphate stones (70%)
• Magnesium ammonium phosphate stones (Struvite) (5-10%)
• Uric acid stones (5-10%)
• Cystine stones (1-2%)
Formation of calcium oxalate and phosphate stones is related to?
hyperparathyroidism, renal tubular acidosis
>> leading to hypercalciuria and hypercalcaemia
Formation of Struvite stones is related to?
infections by urea-splitting bacteria e.g. Proteus > Staghorn calculi may form
Formation of Uric acid stones is related to?
hyperuricaemia, e.g. Gout
Formation of Cystine stones is related to?
genetic defects of renal reabsorption of amino acids, including cystine
Bladder outflow obstruction can lead to which complications?
Bladder hypertrophy - trabeculation
Bladder diverticuli (pouch in bladder wall)
BILATERAL hydroureter and hydronephrosis
Acute retention of urine = acute renal failure
What are lower urinary tract symptoms?
1) Weak stream
4) Urinary frequency and nocturia
How to show Vesicoureteral reflux on scanes?
voiding cystogram with radiologic contrast filling the bladder via a closed bladder catheter
What causes vesicourethral reflux?
Rise in intravesical pressure
What does the severity of reflux depend on?
competence of valve-like effect at the vesicoureteral junction
What is the Grading System of
From grade I to grade V
Reflux extends further up urinary tract
Increasing dilatation and tortuosity of urinary tract
When can vesicourethral reflux cause scarring of kidney?
1. Sterile reflux occurs at high pressure
2. Urine gets infected (chronic pyelonephritis)
What are the 4 types of renal scarring?
Describe the scarring of kidneys due to vesicourethral reflux?
Scar tends to affect upper / lower polar areas (more prone to intrarenal reflux)
Deep cortical scar corresponds with scar in medulla
Causes of papillary necrosis?
1. Diabetes mellitus
2. Analgesic nephropathy
3. Hemoglobinopathies, such as sickle cell
4. Complication of urinary obstruction + infection
Papillary affects kidneys bilaterally or not?
• Usually bilateral but may be unilateral