B5.070 Development of the Urinary System

Question 1

what forms much of the urogenital system

Answer 1

intermediate mesoderm

Question 2

3 evolutionary stages of kidney development

Answer 2

pronephros- not functional
mesonephros
metanephros
develop in a craniocaudal sequence

Question 3

describe the mesonephros

Answer 3

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

Question 4

ureteric bud

Answer 4

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

Question 5

length of nephrogenesis

Answer 5

continues throughout gestation until about 32-36 weeks

Question 6

what forms the filtration units of the kidney

Answer 6

ureteric bud induced metanephric blastemal

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

Question 7

where do kidneys sit in a normal body

Answer 7

about T12

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

Question 8

what is a wilms tumor

Answer 8

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

Question 9

prevalence of wilms tumor

Answer 9

500 cases in US per year

Question 10

pathophys of wilms tumor

Answer 10

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

Question 11

hisopath presentation of wilms tumor

Answer 11

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

Question 12

signs and symptoms of wilms tumor

Answer 12

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

Question 13

diagnosis of wilms tumor

Answer 13

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

Question 14

why is a wilms tumor biopsy not performed

Answer 14

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

Question 15

treatment and prognosis of wilms tumor

Answer 15

surgical removal, plus radiation If tumor has spread

5 year survival is 90%

Question 16

functions of amniotic fluid

Answer 16

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

Question 17

what is polyhydramnios

Answer 17

condition of having too much amniotic fluid

occurs in 1 in 100 pregnancies

Question 18

causes of polyhydramnios

Answer 18

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

Question 19

treatment of polyhydramnios

Answer 19

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

Question 20

what is amnio-reduction

Answer 20

procedure that can drain excess fluids

amniocentesis

Question 21

2 types of renal agenesis

Answer 21

unilateral renal agenesis

bilateral renal agenesis

Question 22

prevalence of unilateral renal agenesis

Answer 22

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

Question 23

effects of unilateral renal agenesis

Answer 23

remaining kidney undergoes slight hypertrophy

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

Question 24

bilateral renal agenesis

Answer 24

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

Question 25

redundant kidney

Answer 25

more than 2 kidneys | very rare

Question 26

rotational anomaly

Answer 26

kidney rotates as it ascends typically unilateral increases chances of hydronephrosis

Question 27

what is the potter sequence?

Answer 27

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

Question 28

potter sequence characteristics

Answer 28

``` 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 ```

Question 29

``` P O T T E R ```

Answer 29

``` pulmonary hypoplasia oligohydramnios twisted face twisted skin extremities defect (due to fetal compression caused by lack of fluid) renal agenesis (in utero) ```

Question 30

horseshoe kidneys

Answer 30

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

Question 31

prevalence of horseshoe kidney

Answer 31

1/500 births

Question 32

ectopic kidneys

Answer 32

pelvic kidney | often in a pancake shape

Question 33

recessive polycystic kidney disease

Answer 33

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

Question 34

dominant polycystic kidney disease

Answer 34

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

Question 35

total prevalence of PKD

Answer 35

200,000 cases/ year in US

Question 36

does the kidney drag its vascular supply when it ascends?

Answer 36

no | induces formation of new arteries (directly off abdominal aorta) and veins (draining into IVC)

Question 37

supernumerary renal arteries

Answer 37

extra arteries/kidney (more than 1) | present in 25-50% of population

Question 38

effects of supernumerary renal arteries

Answer 38

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

Question 39

hydronephrotic kidney

Answer 39

caused by obstruction of the lower ends of the ureter | typically due to supernumerary renal arteries

Question 40

prevalence of duplicated ureters

Answer 40

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

Question 41

cause of duplicated ureters

Answer 41

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

Question 42

bifid ureter

Answer 42

slips between bladder and kidney

Question 43

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

Answer 43

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

Question 44

kidney stone pain in males

Answer 44

may extend caudally into scrotum

Question 45

development of the bladder

Answer 45

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

Question 46

examples urorectal septal defects and formation of the anal pit

Answer 46

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

Question 47

what is the urachus

Answer 47

allantois remnant

Question 48

prevalence of urachus defects

Answer 48

present in 1.03-1.6% of the pediatric population | males slightly more frequent than females

Question 49

normal urachus development

Answer 49

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

Question 50

urachial fistula

Answer 50

20% drains urine from umbilicus from birth periumbilical inflammation

Question 51

urachal sinus

Answer 51

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

Question 52

urachial cysts

Answer 52

43% | present around 2-4 years old

Question 53

urachial diverticulum

Answer 53

2% | often have no symptoms

Question 54

consequences of persistant urachal anomalies

Answer 54

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

Question 55

treatment of urachal defects

Answer 55

typically surgically resected | small risk of recurrence

Question 56

prevalence of bladder exstrophy

Answer 56

1/ 10,000-50,000 live births | more common in males

Question 57

what is bladder exstrophy

Answer 57

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

Question 58

other abnormalities associated with bladder exstrophy

Answer 58

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)

Question 59

male genitalia development with bladder exstrophy

Answer 59

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

Question 60

female genitalia development with bladder exstrophy

Answer 60

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

Question 61

treatment of bladder exstrophy

Answer 61

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

Question 62

esispadias repair

Answer 62

reconstruction of male genitalia with bladder exstrophy | 6-12 months in boys

Question 63

bladder neck reconstruction

Answer 63

reconstruction of urinary sphincter muscles | typically at time of potty training (2-3 years)

Question 64

AFP measurement

Answer 64

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

Question 65

some congenital conditions or diseases in which AFP will be elevated

Answer 65

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