GU
kidneys are seen by 18-22wks pic
urine production by 16 wks
25wks fetal urine output 100mL/day up to 600mL/day at term
bladder fills and empties every 25min, at max rate of 50cc/hr at 40wks
oligohydramnios is the most sensitive detector of GU disease
kidneys span 4-5 vertebral bodies with the length ~= GA [wks]
should not exceed 1/3 diameter of abdomen
ureters should not be visualized and if dilated they touch the spine
Renal Agenesis
bilateral = Potter's syndrome(by pulmonary hypoplasia from no amniotic fluid) which is incompatible with life
unilateral 20X more common than bilateral and has good prognosis
compensatory hypertrophy with normal urine production, and rarely associated with other GU abnormalities
Renal Ectopia
Crossed renal: 1/7000 with single large bilobed ectopic kidney (usually right sided)
associated with obstructive uropathy and VACTERL
Pelvic kidney: 1/1200 found adjacent to bladder or iliac wing
associated with VACTERL
Horseshoe kidney: 1:400 fusion of upper poles at 7-9wks
rarely seen on U/S due to subtle appearance and normal renal function. Malrotation and variable bridge of tissue may give clue
Hydronephrosis pic
AP diameter of renal pelvis >10mm (most sensitive) or when AP diameter of renal pelvis:AP diameter of kidney >0.5 [normal pelvis is <5mm]
with hydronephrosis, F/U fetal U/S are required, and postnatally U/S and scintigraphy is recomended
UPJ obstruction: most commmon cause. 30% bilateral
obstructed kidney can form a giant cyst. Oligohydramnios is rare unless both kidneys affected
UVJ Obstruction: 23% of the time. Usually due to duplication (4% of population)
bilateral ectopic ureterocele in 15%
Congenital Megaureter: distal ureter dysmotility with fusiform proximal ureter dilation
no obstruction, reflux or bladder abnormality. No Tx required
however this cannot be differentiated from UVJ obstruction or vesicouretereal reflux in utero
Urethral Obstruction
variable & can have insidious onset
prox urethral & bladder dilation (massive) with bladder wall hypertrophic thickening (trabeculation), with dilation of prostatic urethra in males leads to "keyhole" appearance
oligohydramnios in 50%, and may be severe
Male cause post urethral valves pic
Female - consider caudal regression, urethral atresia (rare)
Bladder or ureters may decompress via rupture (bad prognosis) indicates high pressure which often leads to renal dysplasia with abnormally echogenic kidneys occasionallly with cysts
Approach to Echogenic Kidneys
Autosomal recessive polycystic kidney disease (infantile PCKD)-always with hepatic portal fibrosis, parents usually have no renal anomalies. High mortality in infancy, if survives, usually need dialysis by 15yrs
Autosomal dominant polycystic kidney disease (mean age of diagnosis 40's, 50% a/w hepatic cysts > pancreatic cysts > splenic cysts. Renal failure by 60's. Therefore scan parents for cysts as a discriminator.
multicystic dysplastic: nongenetic variable size cysts
aneuploidy: trisomy 13 gets echogenic kidney and crossed fingers
Meckel Gruber syndrome: also associated with finger anomalies
Renal Cysts
if no obstruction present, look for associated VACTERL anomalies
Renal Dysplasia: 90% from obstruction during nephrogenesis prior to 20wks
results in disorganized parenchymal development with marked increase in fibrous tissue and multiple tiny cysts (below the resolution of U/S) resulting in echogenic kidneys pic
NB cysts are smaller than MCDK but can look similar
hydronephrosis is often present
Multicystic Dysplastic Kidney (MCDK) usually caused by UPJ obstruction
kidney replaced by numerous variable size noncommunicating cysts of tubular origin. May involve sparing of proximal pole
most common cause of fetal abdominal masses after hydronephrosis
40% of cases have anomalous development of opposite kidney which 30% of the time if severe oligohydramnios is fatal
Autosomal recessive polycystic kidneys (=infantile polycystic kidneys) pic
bilat medullary ectasia with innumerable <2mm cysts and nonobstructed tubules
has large very echogenic kidneys with anechoic medulla at 16wks
can revert to normal shape later in third trimester
can get pulmonary hypoplasia from severe oligohydramnios
Infantile Type - die at birth, severe cystic kidneys, minimal liver involvement
Juvenile Type - severe liver involvement, minimal renal dysfunction
Autosomal dominant polycystic kidneys pic
normal amniotic fluid with echogenic and cystic kidneys
need chorionic villus sampling for diagnosis
30% get hepatic cysts
Heredofamilial Cystic Dysplasias - with associated renal cysts:
Meckel-Gruber Syn - auto rec, bilateral nonobstructive cystic dysplasia
occipital encephalocele, microcephaly & polydactyly
Jeune Syndrome - Asphyxiating Throacic Dystrophy, nonobstructive dysplasia
Ehlers-Danlos & Von Hippel-Lindau - frequently renal cysts associated
Solid Renal Masses (rare)
Mesoblastic nephroma (most common) is a solitary hamartoma with benign course
frequently with polyhdramnios, but no preterm delivery needed
nephrectomy curative with rare recurrence
U/S solid protrusion with no defined capsule. pic Can mimic Wilm's
Wilm's tumors are very rare in utero
Bladder Extrophy pic
1:25k, eversion and exteriorization. Is related to rare cloacal extrophy (link)
debris in bladder indicates enterovesicular fistula
patent urachus allows communication to anterior abdominal wall
urachal cyst may resemble a distended or abnormal shaped bladder
does not empty or fill, watch for 60-90min for confirmaition
Ovaries and Vagina only seen if pathologically enlarged
Hydrometrocolpos: hypoechoic mass post to bladder
50% compress urinary tract & cause hydronephrosis
Ovarian Cysts - No urinary compresion, multiseptated
due to maternal hormone, benign but associated with hypothyroidism
torsion possible , may require surgical reducuction
DDx: duplication (more tubular), mesenteric cyst
Urachal cyst (extend to umbilicus) from bladder wall
Gender Assessment - when needed for genetic abnormality assessment
identify testis in scrotum is only way to have 100% prediction
cannot be performed reliably before 28wks
30% have poor visualization of perineum, especially before 24wks
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urine production by 16 wks
25wks fetal urine output 100mL/day up to 600mL/day at term
bladder fills and empties every 25min, at max rate of 50cc/hr at 40wks
oligohydramnios is the most sensitive detector of GU disease
kidneys span 4-5 vertebral bodies with the length ~= GA [wks]
should not exceed 1/3 diameter of abdomen
ureters should not be visualized and if dilated they touch the spine
Renal Agenesis
bilateral = Potter's syndrome(by pulmonary hypoplasia from no amniotic fluid) which is incompatible with life
unilateral 20X more common than bilateral and has good prognosis
compensatory hypertrophy with normal urine production, and rarely associated with other GU abnormalities
Renal Ectopia
Crossed renal: 1/7000 with single large bilobed ectopic kidney (usually right sided)
associated with obstructive uropathy and VACTERL
Pelvic kidney: 1/1200 found adjacent to bladder or iliac wing
associated with VACTERL
Horseshoe kidney: 1:400 fusion of upper poles at 7-9wks
rarely seen on U/S due to subtle appearance and normal renal function. Malrotation and variable bridge of tissue may give clue
Hydronephrosis pic
AP diameter of renal pelvis >10mm (most sensitive) or when AP diameter of renal pelvis:AP diameter of kidney >0.5 [normal pelvis is <5mm]
with hydronephrosis, F/U fetal U/S are required, and postnatally U/S and scintigraphy is recomended
UPJ obstruction: most commmon cause. 30% bilateral
obstructed kidney can form a giant cyst. Oligohydramnios is rare unless both kidneys affected
UVJ Obstruction: 23% of the time. Usually due to duplication (4% of population)
bilateral ectopic ureterocele in 15%
Congenital Megaureter: distal ureter dysmotility with fusiform proximal ureter dilation
no obstruction, reflux or bladder abnormality. No Tx required
however this cannot be differentiated from UVJ obstruction or vesicouretereal reflux in utero
Urethral Obstruction
variable & can have insidious onset
prox urethral & bladder dilation (massive) with bladder wall hypertrophic thickening (trabeculation), with dilation of prostatic urethra in males leads to "keyhole" appearance
oligohydramnios in 50%, and may be severe
Male cause post urethral valves pic
Female - consider caudal regression, urethral atresia (rare)
Bladder or ureters may decompress via rupture (bad prognosis) indicates high pressure which often leads to renal dysplasia with abnormally echogenic kidneys occasionallly with cysts
Approach to Echogenic Kidneys
Autosomal recessive polycystic kidney disease (infantile PCKD)-always with hepatic portal fibrosis, parents usually have no renal anomalies. High mortality in infancy, if survives, usually need dialysis by 15yrs
Autosomal dominant polycystic kidney disease (mean age of diagnosis 40's, 50% a/w hepatic cysts > pancreatic cysts > splenic cysts. Renal failure by 60's. Therefore scan parents for cysts as a discriminator.
multicystic dysplastic: nongenetic variable size cysts
aneuploidy: trisomy 13 gets echogenic kidney and crossed fingers
Meckel Gruber syndrome: also associated with finger anomalies
Renal Cysts
if no obstruction present, look for associated VACTERL anomalies
Renal Dysplasia: 90% from obstruction during nephrogenesis prior to 20wks
results in disorganized parenchymal development with marked increase in fibrous tissue and multiple tiny cysts (below the resolution of U/S) resulting in echogenic kidneys pic
NB cysts are smaller than MCDK but can look similar
hydronephrosis is often present
Multicystic Dysplastic Kidney (MCDK) usually caused by UPJ obstruction
kidney replaced by numerous variable size noncommunicating cysts of tubular origin. May involve sparing of proximal pole
most common cause of fetal abdominal masses after hydronephrosis
40% of cases have anomalous development of opposite kidney which 30% of the time if severe oligohydramnios is fatal
Autosomal recessive polycystic kidneys (=infantile polycystic kidneys) pic
bilat medullary ectasia with innumerable <2mm cysts and nonobstructed tubules
has large very echogenic kidneys with anechoic medulla at 16wks
can revert to normal shape later in third trimester
can get pulmonary hypoplasia from severe oligohydramnios
Infantile Type - die at birth, severe cystic kidneys, minimal liver involvement
Juvenile Type - severe liver involvement, minimal renal dysfunction
Autosomal dominant polycystic kidneys pic
normal amniotic fluid with echogenic and cystic kidneys
need chorionic villus sampling for diagnosis
30% get hepatic cysts
Heredofamilial Cystic Dysplasias - with associated renal cysts:
Meckel-Gruber Syn - auto rec, bilateral nonobstructive cystic dysplasia
occipital encephalocele, microcephaly & polydactyly
Jeune Syndrome - Asphyxiating Throacic Dystrophy, nonobstructive dysplasia
Ehlers-Danlos & Von Hippel-Lindau - frequently renal cysts associated
Solid Renal Masses (rare)
Mesoblastic nephroma (most common) is a solitary hamartoma with benign course
frequently with polyhdramnios, but no preterm delivery needed
nephrectomy curative with rare recurrence
U/S solid protrusion with no defined capsule. pic Can mimic Wilm's
Wilm's tumors are very rare in utero
Bladder Extrophy pic
1:25k, eversion and exteriorization. Is related to rare cloacal extrophy (link)
debris in bladder indicates enterovesicular fistula
patent urachus allows communication to anterior abdominal wall
urachal cyst may resemble a distended or abnormal shaped bladder
does not empty or fill, watch for 60-90min for confirmaition
Ovaries and Vagina only seen if pathologically enlarged
Hydrometrocolpos: hypoechoic mass post to bladder
50% compress urinary tract & cause hydronephrosis
Ovarian Cysts - No urinary compresion, multiseptated
due to maternal hormone, benign but associated with hypothyroidism
torsion possible , may require surgical reducuction
DDx: duplication (more tubular), mesenteric cyst
Urachal cyst (extend to umbilicus) from bladder wall
Gender Assessment - when needed for genetic abnormality assessment
identify testis in scrotum is only way to have 100% prediction
cannot be performed reliably before 28wks
30% have poor visualization of perineum, especially before 24wks
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