Fetal Urogenital System Abnormalities

SONO: normal fetal kidneys

• homogeneous corte

• moderately hypoechoic cortex

• hypoechoic pyramids and anechoic collecting system

• kidneys are evaluated for:

  • size

  • collecting system dilation

  • appearance (texture and echogenicity)

renal agenesis (unilateral and bilateral)

• complete absence of one or both kidneys due to failure of development

• associated with genital anomalies and 2VC

• unilateral agenesis:

  • MC than bilateral

  • excellent prognosis

• bilateral agenesis:

  • lethal prognosis

  • exhibit classic Potter’s syndrome

  • oligohydramnios

  • pulmonary hypoplasia

  • associated with cardiac defects and MSK disorders

SONO: unilateral renal agenesis

• absent kidney on one side

• contralateral kidney → compensatory hypertrophy

• ipsilateral adrenal: flattened; occupies renal fossa

• absent ipsilateral renal artery branch

• normal AFI

• normal bladder

**sweep from chest to bladder to check for ectopic

SONO: bilateral renal agenesis

• absent kidneys

• adrenals: flattened within renal fossa

• absent renal artery branches

• bladder: not visualized; no urine (observe for 1 hours)

• AFI: oligo- or anhydramnios

renal ectopia

• kidney not positioned within renal fossa

  • usually lies in area of pelvis

• crossed ectopia: both kidneys may be fused or appear to be fused

  • located on same side (usually right)

  • considered form of horseshoe kidney

• prognosis: depends on presence of additional anomalies; generally good

• associated with:

  • skeletal, GYN, GI, and cardiovascular anomalies

SONO: renal ectopia

• absence of kidney in its normal position

• ipsilateral adrenal gland flattening

• ectopic kidney is usually in pelvis and may be malrotated

  • crossed ectopia and cross-fused ectopia is possible

horseshoe kidneys

• inferior poles of kidney fuse while in pelvis

• may be found as isolated anomaly or be associated with other anomalies or syndromes

• isolated horseshoe kidneys carry good prognosis

• incidence of trisomy 18 and 45, X

SONO: horseshoe kidneys

• bridge of tissue connecting the lower poles

• if spine down, connecting isthmus may be seen anterior to AO

**coronal view is ideal

autosomal recessive polycystic kidney disease

• aka infantile PKD

• autosomal recessive congenital disorder that affects both fetal kidneys and liver

• characterized by:

  • numerous small cysts in both kidneys and liver

  • enlarged, nonfunctioning collecting tubules within the kidneys=renal failure

• may be part of genetic syndrome—such as Meckel-Gruber or T13

• prognosis: poor; decreased renal function and hypertension; death at an early age

SONO: autosomal recessive polycystic kidney disease

• bilateral, enlarged, echogenic kidneys

  • individual cysts not identified

• kidneys are symmetrically enlarged

  • 3-10x normal renal size for GA

• AC will be large

• bladder may be present or small

• oligohydramnios

multicystic dysplastic kidney

• characterized by:

  • cystic lesions that correspond primarily to dilated collecting tubules

  • cysts replace renal tissue (kidney doesn’t function)

  • cysts are nonfunctioning and noncommunicating

• usually unilateral; can be bilateral

• MC form of renal cystic disease in childhood

• associated with Meckel-Gruber; CNS, GI, cardiac, and limb anomalies

• prognosis

  • unilateral=excellent

  • bilateral=lethal

SONO: multicystic dysplastic kidney (unilateral vs bilateral)

unilateral

• multiple, smooth-walled cysts of varying sizes

• cysts do not communicate with each other

• normal appearing contralateral kidney

• bladder is visible

• normal AFI

bilateral

• multiple, noncommunicating renal cysts within both kidneys

• failure to visualize bladder

• severe oligohydramnios

autosomal dominant polycystic kidney disease

• aka adult PKD

• autosomal dominant congenital disorder that causes cystic dilation of nephrons and collecting tubules

  • macrocysts in kidneys, liver, and pancreas

• may not be detected antenatally since it does not usually manifest until later in life

• prognosis: variable when found in child

SONO: autosomal dominant polycystic kidney disease

• bilateral (rare unilateral)

• similar to ARPKD

• symmetrically enlarged echogenic kidneys

• amniotic fluid may be normal

  • unlike ARPKD, which has oligohydramnios

• visible bladder

• kidneys may look normal in 2nd trimester; follow up if family hx of ADPKD

obstructive cystic dysplasia

• renal dysplasia occurs secondary to long standing kidney obstruction in the 1st/early 2nd trimester

• leads to fibrosis and cystic replacement of renal tissue

• if unilateral disease:

  • from UPJ or UVJ obstruction

  • variable prognosis: depends on additional anomalies

• if bilateral disease:

  • from bladder outlet obstruction

  • poor prognosis b/c no AFI → renal failure and pulmonary hypoplasia

SONO: obstructive cystic dysplasia

• echogenic kidneys containing peripheral cortical cysts

  • variable number/size of cysts

• renal size can be small or enlarged

• if bilateral disease from bladder outlet obstruction

  • thick-walled bladder; severe oligohydramnios

• early disease may show hydronephrosis/hydroureter

hydronephrosis

• dilation of the renal pelvis in response to urine blockage

  • blockage in the ureter, bladder, or urethra

  • fluid-filled renal pelvis and calyces

• MC fetal anomaly

• unilateral or bilateral

• associated with numerous conditions

• prognosis depends on severity and underlying cause

SONO: hydronephrosis

• dilated anechoic renal pelvis

• measurement criteria:

  • measure renal pelvis in AP (TRV image, spine anterior)

  • <7mm=mild hydro

  • 7-10mm=moderate hydro

  • >15mm=severe hydro

**sweep up and down in TRV to prove its kidney

ureteropelvic junction obstruction (UPJ)

• obstruction at the junction b/w renal pelvis and ureter

• MC location for renal obstruction

• MC cause of hydro in neonate

• considered congenital hydronephrosis

• MC male

• usually unilateral

SONO: ureteropelvic junction obstruction (UPJ)

• medial anechoic urine collection within renal pelvis that communicates with calyces (caliectasis)

• moderate to severe hydronephrosis without hydroureter or bladder dilation

• distended renal calyces connect with renal pelvis

• enlarged kidney

• if unilateral, bladder and AFI are normal

• if bilateral, bladder will be empty and may have oligohydramnios

ureterovesical junction obstruction (UVJ)

• obstruction at the junction of the ureter and bladder

• hydronephrosis occurs secondary to obstruction

  • dilated ureter also forms: megaureter

• possibly from ectopic ureterocele within bladder causing obstruction of upper pole of kidney

• males?females (biological)

• may be unilateral or bilateral

• definitive diagnosis is made with VCUG or ceVUS

SONO: ureterovesical junction obstruction (UVJ)

• affected kidney will have dilation of renal pelvis and ureter

• ureter will appear tortuous

• if unilateral, bladder and AFI are normal

• if bilateral, bladder will be empty and may have oligohydramnios

posterior urethral valve obstruction

• obstruction produced by abnormal congenital membrane within posterior urethra

  • leads to hydronephrosis, hydroureter, bladder dilation, and dilated proximal urethra

• degree of obstruction can be complete, partial, or intermittent

• MC urethral anomaly

• occurs only in males (biological)

• prognosis depends on severity of obstruction

posterior urethral valve obstruction

• bladder wall severely thickened with dilated posterior urethra

• “keyhole sign”

• bladder wall thickening

• marked bilateral hydronephrosis and dilated tortuous ureters

• occurs only in male fetuses

• diminishing AFI

what do you see?

prune belly syndrome

• aka Eagle-Barrett Syndrome

• rare congenital disorder characterized by:

  • dilation of collecting system, cryptorchidism, and agenesis/hypoplasia of abdominal wall muscles

• seen mostly in male fetuses

• associated with megacystitis and posterior urethral valves

• prognosis depends on severity and renal function

SONO: prune belly syndrome

• hypoplastic/absent anterior abdominal muscles

• protrusion of anterior abdominal wall

• massively distended bladder

• dilated, tortuous ureters

• cryptorchidism

• dilated prostatic urethra

• kidneys may be normal, hydronephrotic, or dysplastic

ureterocele

• cystic dilation of intravesical (bladder) segment of distal ureter

• often found in duplex collecting systems

  • ureter attached to ureterocele in duplex collecting system drains upper pole of kidney as it enters bladder in more medial and caudal position (ectopic ureter)

• females are more likely to present with ureteroceles

• unilateral or bilateral

SONO: ureterocele

• best visualized when the bladder is somewhat full

• anechoic cystic surrounding by a thin echogenic membrane within the bladder

• if bladder empty, ureterocele may be mistaken for small bladder

• if bladder too full, ureterocele may be compressed

• bladder should be evaluated multiple times through examination

• possible renal duplication

fetal renal tumors

• tumors of the fetal kidneys are rare

• MC fetal renal tumor is mesoblastic nephroma (hamartoma)

  • benign tumor

  • composed of oddly arranged indigenous tissue

• Wilms’ tumor is malignant renal tumor; MC in females

• neuroblastoma is a malignant adrenal tumor

renal tumors

hydrocele

• accumulation of serous fluid surrounding testicle, resulting from communication with peritoneal cavity

• SONO: simple or complex

cryptorchidism (undescended testicle)

• if descent interrupted or stopped testes will remain located within inguinal canal

• referred to as undescended testes, or cryptorchidism

• risk of torsion and development of cancer

• scrotal sac with no testicular tissue

• SONO: anechoic fluid seen in scrotum

hydrometrocolpos

• obstruction of uterus and vagina resulting in collections of fluid (hydrometrocolpos)

• from atresia/blockage of vagina or cervix, imperforate hymen, or abnormal membranes within vaginal lumen

• masses may be predominantly cystic, may contain midlevel echoes, or may be fluid-debris levels

• SONO: hypoechoic “cyst-like” ovoid mass posterior to bladder in area of uterus

ovarian cyst

• ovarian cyst that results from maternal hormonal stimulation

• usually benign

• typically represent normal functional ovarian cysts

• MC cystic mass in female fetuses

• can be unilateral or bilateral

• most regress in utero or postnatally

• have the potential to lead to ovarian torsion or rupture