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Flashcards in Abnormalities in renal tract / bladder Deck (19):
1

What are the causes of cystic renal disease?

ADPKD
ARPKD
Medullary cystic disease (juvenile nephronophthisis)
Renal genesis
Renal dysplasia
Tuberous sclerosis

2

What are the features of ADPKD?

Renal failure in middle age
- can present with haematuria / HTN / flank pain or masses in childhood

Contiguous gene syndrome (large deletion of PKD and adjacent gene for tuberous sclerosis)

Associated with extra renal manifestation
- cerebral aneurysms
- hepatic cysts (rarely fibroses)
- cardiac valve disease (mitral valve prolapse, AR, mitral / tricuspid regard)
- colonic diverticula
- abdominal wall / inguinal hernia

3

What are the features of ARPKD?

Bilateral dilation of collecting ducts forming sausage shaped cysts

Congenital hepatic fibrosis ALWAYS present
- leads to portal HTN in small number
May die due to pulmonary hypoplasia
Less affected children tend to develop HTN in early childhood and slowly progress to CKD

4

What is medullary cystic disease?

Medullary cystic disease - Autosomal dominant
Juvenile nephronophthisis - Autosomal recessive

Cysts in the medulla causing:
- progressive inflammation --> tubulointerstitial sclerosis
Leads to:
- One of the most common causes of ESRF in childhood and dialysis / transplantation usually required by age of 10-12y

Affected gene
- Infantile: NPHP2 gene
- Juvenile: NPHP1 (most common)
- Adolescent: NPHP3

5

What are the clinical features of medullary cystic disease?

Growth failure
Anaemia
Polyuria and polydipsia due to concentration defect
Children commonly have red or blond hair
Urinalysis normal
- proteinuria late finding reflecting dev. of secondary glomerulosclerosis
Imaging
- small / poorly functional kidneys at later stages
- infantile form --> large kidneys w cysts
- detected prenatally with oligohydramnios a/w renal abN by 22 weeks
HTN late in disease (unless infantile form)
- delayed due to tendency to sodium wasting

A/w extra-renal findings
- 80% in infantile form

Unlike faconi --> would expect glucose in the urine, probably more proteinuria, and more electrolyte imbalances (potassium, phosphate, etc)

6

What's renal agenesis?

Large fluid-filled cyst with no renal tissue and no connection to bladder, caused by failure of union
- ureteric bud (which forms ureter / pelvis / calyces and collecting duct) AND
- nephrogenic mesenchyme

7

What does bilateral renal agenesis cause?

Potter syndrome
- severe oligohydramnios resulting in
- beaked nose, misshapen and low set ears
- positional defects like talipes, hip dislocation
- pul. hypoplasia

8

What is Prune belly syndrome?

Constellation of
- hypoplasia of muscles of anterior abode wall
- bilateral undescended testes
- variable degree of renal involvement (from nothing to complete genesis)
- Urinary tract dilation
- oligohydramnios with pul. hypoplasia / club foot

MALES ONLY

9

What are causes for hydronephrosis?

Most common GU abN on a/N ultrasound
Often due to obstruction

Possible causes:
- PUJ obstruction
- VUR
- Multicystic kidneys
- Megaureter
- Posterior urethral valves
- Prune Belly syndrome
- Ectopic ureter / ureterocele
- Urethral atresia

10

What is posterior urethral valves associated with?

VUR (60%)

diagnosis made by MCU
- shows that posterior urethra is dilated and elongated from the bladder neck to level of valves, obstructing outflow of urine from bladder

11

What's the outcome for babies with posterior urethral valves?

VUR and persistent post-obstructive hydronephrosis is common

Approx 30% will have ESRF or CKD
- many patients will have polyuria secondary to diminished ability to concentrate urine
- Some boys will develop renal tubular acidosis

Poor prognostic indicators includes:
- Oligohydramnios
- Hydornephrosis before 24 wks gestation
- Persistently elevated Cr / bilateral cortical cysts
- Diurnal enuresis beyond 5y

12

What is duplex kidney?

Premature division of ureteric buds leading to double drainage of kidney

Total: two distinct ureters
- upper pole ureter drains to a site distal to lower pole ureter
- upper pole may drain to site outside bladder (urethra or vagina causing incontinence or may be obstructed causing uretocele
- lower pole has increased tendency to reflux

Incomplete: bifid renal pelvis

13

What are some risk factors for developing UTI?

Gender (F > M except in first 3m of life)
Circumcision (uncircumcised boys 10-15x more likely to get UTI)
Underlying anatomical abnormality (mostly VUR)

14

What is the inheritance pattern of VUR?

Autosomal dominant with variable penetrance
- 15-20% of siblings / offspring affected
- Screen families if Grade 3 reflux or worse

15

What are the grades of VUR?

1: reflux into non-dilated ureter
2: reflux into ureter / pelvis / calyces w/o dilation
3: dilation and or tortuosity
4: dilation and/or turtuosity with moderate dilation of renal pelvis and calyces
5: grade 4 and loss of papillary impression in majority of calyces

16

What are the spont resolution w/in 5 years for each grade of VUR?

Grade 1 and 2: 80-90%
Grade 3: 45%
Grade 4: 25%
Grade 5: always requires surgical intervention

Chances for resolution better for unilateral rather than bilateral

17

What is the most common cause of daytime incontinence?

Bladder with detrusor instability
- sx of urinary frequency, urgency and urge incontinence.

Features
- The bladder is smaller than normal and exhibits strong uninhibited contractions.
- In females, a history of recurrent UTIs is common.

Management
- timed voiding
- treatment of constipation and UTIs is important.
- Pelvic floor exercises are also found to reduce or eliminate unstable bladder contractions. - alpha blocker may aid in bladder emptying by promoting bladder neck relaxation

18

What causes a large capacity highly complaint bladder?

Voiding postponement o
- habitually postpone micturition, often in specific settings
- a/w behavioural issues or have a psychological comorbidity.

Pathophysiology
- the detrusor muscle becomes overstretched and hypoactive leading to a weak or absent contraction referred to as an underactive bladder, which was formerly called "lazy bladder syndrome" or myogenic failure.
- Urodynamic evaluation will demonstrate a large-capacity but compliant bladder and an interrupted urinary flow pattern is often observed.
- Children with underactive bladders are at increased risk for urinary tract infection because of post-void residuals.

19

What's giggle incontinence?

Sudden relaxation of urinary sphincter during giggling resulting in the entire bladder volume being lost
- typically affects girls 7-15 years of age
- one proposed mechanism is similar to that of cataplexy, in which an emotional event causes muscle hypotonia.
- Anticholinergic medication (based upon the assumption that incontinence is related to detrusor instability) and timed voiding occasionally are effective.
- Small case series reports show effectiveness of low-dose methylphenidate.
- In one small case series, biofeedback was effective in nine patients with giggle incontinence either refractory to medications or whose parents refused pharmacotherapy.