B5.070 Development of the Urinary System Flashcards

1
Q

what forms much of the urogenital system

A

intermediate mesoderm

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2
Q

3 evolutionary stages of kidney development

A

pronephros- not functional
mesonephros
metanephros
develop in a craniocaudal sequence

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3
Q

describe the mesonephros

A

functional during embryonic development
mesonephric duct carries urine from mesonephros to fetal cloaca (sewer)…later becomes male reproductive system
paramesonephric duct becomes female reproductive system

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4
Q

ureteric bud

A

outgrowth from the mesonephric duct
will induce the formation of the metanephric kidney
forms within intermediate mesoderm towards caudal portion of embryo

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5
Q

length of nephrogenesis

A

continues throughout gestation until about 32-36 weeks

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6
Q

what forms the filtration units of the kidney

A

ureteric bud induced metanephric blastemal

endoderm (collecting tubules) fused with mesoderm (rest of nephron)

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7
Q

where do kidneys sit in a normal body

A

about T12

rise from S1 due to differential growth, no muscles pull them up

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8
Q

what is a wilms tumor

A

nephroblastoma
most common primary renal tumor affecting children and the 4th most common pediatric tumor
account for 9/10 kidney cancers in children

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9
Q

prevalence of wilms tumor

A

500 cases in US per year

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10
Q

pathophys of wilms tumor

A

mutation in WT-1 gene
mutations in or loss of WT1 or WT2 gene
tumor suppressor genes found on chromosome 11

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11
Q

hisopath presentation of wilms tumor

A
tightly packed cells
fibrocytic or spindle shaped cells
poorly-formed tubules
classic triphasic combination of cells:
1. blastemic
2. stromal
3. epithelial
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12
Q

signs and symptoms of wilms tumor

A
painless, palpable abdominal mass
loss of appetite
abdominal pain
fever
nausea and vomiting
blood in the urine
high BP
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13
Q

diagnosis of wilms tumor

A

painless abdominal tumor felt by a doctor
US done first followed by CT or MRI
tumor biopsy NOT performed

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14
Q

why is a wilms tumor biopsy not performed

A

risk of creating fragments of cancer tissue and seeding the abdomen with malignant cells

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15
Q

treatment and prognosis of wilms tumor

A

surgical removal, plus radiation If tumor has spread

5 year survival is 90%

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16
Q

functions of amniotic fluid

A

cushioning the embryo
control of the body temperature
prevents adherence of amnion to the embryo
permits symmetrical external growth of the embryo
free movement of embryo
lung development

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17
Q

what is polyhydramnios

A

condition of having too much amniotic fluid

occurs in 1 in 100 pregnancies

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18
Q

causes of polyhydramnios

A
GI abnormalities: esophageal atresia, duodenal atresia, tracheoesophageal fistula
fatal renal disorders (renal agenesis)
Downs and Edwards syndromes
anencephaly (impairs swallowing reflex)
maternal DM
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19
Q

treatment of polyhydramnios

A

medications that reduce fluid production are as much ad 90% effective
indomethacin used for idiopathic or maternal DM polyhydramnios- cuts down on renal output of the fetus
if caused by a structural lesion, indomethacin doesn’t solve the issue but can decrease distention

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20
Q

what is amnio-reduction

A

procedure that can drain excess fluids

amniocentesis

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21
Q

2 types of renal agenesis

A

unilateral renal agenesis

bilateral renal agenesis

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22
Q

prevalence of unilateral renal agenesis

A

1/1000 births
slightly more common in males
not major unless other defects are present

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23
Q

effects of unilateral renal agenesis

A

remaining kidney undergoes slight hypertrophy

sometimes diagnosed during prenatal US, but usually unknown to affected individual

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24
Q

bilateral renal agenesis

A

1/8000-10000 births
65-80% males
due to oligohydramnios during gestation
incompatible with postnatal life

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25
Q

redundant kidney

A

more than 2 kidneys

very rare

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26
Q

rotational anomaly

A

kidney rotates as it ascends
typically unilateral
increases chances of hydronephrosis

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27
Q

what is the potter sequence?

A

characteristics exhibited by infants born with bilateral renal agenesis
typically die due to respiratory failure
may also be caused by chronic placental failure

28
Q

potter sequence characteristics

A
flattened nose
wide interpupillary space
receding chin
tapering fingers
low set ears
hip dislocation
clubbed feet
pulmonary hypoplasia
males lack vas deferens and seminal vesicles
females lack uterus and upper vagina
29
Q
P
O
T
T
E
R
A
pulmonary hypoplasia
oligohydramnios
twisted face
twisted skin
extremities defect (due to fetal compression caused by lack of fluid)
renal agenesis (in utero)
30
Q

horseshoe kidneys

A

thought to be due to fusion of right and left metanephric kidneys in the midline while in the pelvis
rise is limited by IMA

31
Q

prevalence of horseshoe kidney

A

1/500 births

32
Q

ectopic kidneys

A

pelvic kidney

often in a pancake shape

33
Q

recessive polycystic kidney disease

A

1/20,000-40,000
cysts from collecting tubules
renal failure in infancy

34
Q

dominant polycystic kidney disease

A

1/500-1000
cysts from anywhere
renal failure in adulthood

35
Q

total prevalence of PKD

A

200,000 cases/ year in US

36
Q

does the kidney drag its vascular supply when it ascends?

A

no

induces formation of new arteries (directly off abdominal aorta) and veins (draining into IVC)

37
Q

supernumerary renal arteries

A

extra arteries/kidney (more than 1)

present in 25-50% of population

38
Q

effects of supernumerary renal arteries

A

may block urine flow out of the ureter, causing hydronephrosis
esp when additional arteries are caudal to the renal pelvis

39
Q

hydronephrotic kidney

A

caused by obstruction of the lower ends of the ureter

typically due to supernumerary renal arteries

40
Q

prevalence of duplicated ureters

A

most common renal abnormality
1% of population
found in 8% of kids with UTIs
more common in Caucasians and females

41
Q

cause of duplicated ureters

A

ureteric bud either splits or arises twice

in most case, kidney is divided into upper and lower lobe with some overlap due to intermingling of collecting tubules

42
Q

bifid ureter

A

slips between bladder and kidney

43
Q

3 typical sites of sites of urinary caliculi (kidney stones)

A
  1. junction of renal pelvis with ureter
  2. as ureters cross iliac blood vessels at pelvic rim
  3. junction of ureter with bladder wall
44
Q

kidney stone pain in males

A

may extend caudally into scrotum

45
Q

development of the bladder

A

division of the cloaca by the urorectal septum into a dorsal rectum and a ventral urogenital sinus
epithelium of the bladder forms from urogenital sinus while other layers form from splanchnopleuric mesenchyme

46
Q

examples urorectal septal defects and formation of the anal pit

A

urorectal fistula
rectovaginal fistula
rectoperitoneal fistula
anal pit (anal atresia)

47
Q

what is the urachus

A

allantois remnant

48
Q

prevalence of urachus defects

A

present in 1.03-1.6% of the pediatric population

males slightly more frequent than females

49
Q

normal urachus development

A

channel of urachus usually seals off and obliterates around the 12th week of gestation
all that is left is a small fibrous cord between the bladder and umbilicus called the median umbilical ligament

50
Q

urachial fistula

A

20%
drains urine from umbilicus from birth
periumbilical inflammation

51
Q

urachal sinus

A

35%
can be asymptomatic
may present with umbilican infections with abdominal pain and drainage of some fluid

52
Q

urachial cysts

A

43%

present around 2-4 years old

53
Q

urachial diverticulum

A

2%

often have no symptoms

54
Q

consequences of persistant urachal anomalies

A

continuous bladder and urine drainage around the umbilicus (42%)
recurrent urinary tract infections (5-10%)
urachal carcinoma (0.01%)

55
Q

treatment of urachal defects

A

typically surgically resected

small risk of recurrence

56
Q

prevalence of bladder exstrophy

A

1/ 10,000-50,000 live births

more common in males

57
Q

what is bladder exstrophy

A

abnormality of formation of the anterior bladder wall and the bony pelvis
bladder does not form in its normal round shape and is instead flattened and exposed on the abdominal wall
pelvic bones widely separated

58
Q

other abnormalities associated with bladder exstrophy

A

first child has it, second child has 1/100 chance
1/70 for a child w a parent with it
associated with elevated AFP levels (diagnosed at routine US at 16 weeks)

59
Q

male genitalia development with bladder exstrophy

A

penis may appear short and curved in an upward direction

testicles may not be in a normal position in the scrotum and a hernia may be seen

60
Q

female genitalia development with bladder exstrophy

A

clitoris and labia minora are separated and spread apart
vagina and urethra are shorter
uterus, fallopian tubes, and ovaries are generally normal

61
Q

treatment of bladder exstrophy

A
surgery initiated shortly after birth
bladder closure
closure of anterior abdominal wall
pelvic osteotomy
baby in hospital for 3-4 weeks
62
Q

esispadias repair

A

reconstruction of male genitalia with bladder exstrophy

6-12 months in boys

63
Q

bladder neck reconstruction

A

reconstruction of urinary sphincter muscles

typically at time of potty training (2-3 years)

64
Q

AFP measurement

A

measured in pregnant women through the analysis of maternal blood or amniotic fluid, as a screening test for a subset of developmental abnormalities
performed during the 16-19 week mark of pregancy

65
Q

some congenital conditions or diseases in which AFP will be elevated

A
omphalocele
gastroschisis
HCC
neural tube defects
nonseminomatous germ cell tumors
yolk sac tumor
exstrophy of the bladder