CHAPTER 29 - THE FETAL GENITOURINARY SYSTEM

Hydronephrosis

Another name for pelvocaliectasis is;

Pelvis

Before 9 weeks, the fetal kidneys are located within the;

Omphalocele Spina Bifida Imperforate anus

Cloacal exstrophy is associated with all of the following;

The fetal pelvis should always be analyzed because it's the most common location for an ectopic kidney. In presence of unilateral renal agenesis, the contralateral kidney will enlarge.

Compensatory hypertrophy;

Megacystis, dilated urinary bladder and urethra, abdominal muscle hypertrophy

Components of prune belly syndrome;

Undescended testicles

Cryptorchidism describes;

MDCK disease

Numerous noncommunicating anechoic masses are noted within the left renal fossa of a fetus at 20 weeks' gestation. What is the most likely etiology of these masses?

Cloacal exstrophy

OEIS complex is also referred to as;

Enlarged bladder and dilated urethra

The ''keyhole'' sign best describes;

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The keyhole sign is seen when there is dilation of the urinary bladder and posterior urethra

ADPKD

The type of renal cystic disease associated with adult liver and pancreatic cyst is;

The point where the renal pelvis meets the ureter.

Ureteropelvic Junction

Posterior urethral valves

What would cause a bladder outlet obstruction?

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ARPKD would be most likely cause of enlarged, echogenic kidneys noted in utero.

Triangular shaped hypoechoic structures located superior to the upper pole of kidneys.

Adrenal glands;

Birth defect in which the sex of the fetus cannot be determined. Findings of abnormal external genitalia in male are micropenis, hypospadias and undescended testicles. Fetal hydroceles are common findings in utero and may become fairly large.

Ambiguous Genitalia

Ureter and renal collecting system

An obstruction at the ureterovesicular junction would lead to dilation of the;

ADPKD doesn't typically manifest until appx. the 4th or 5th decade of life at which the adult will develop renal cysts and may die from end-stage renal failure. It is also associated with the development of cysts within the liver, pancreas and spleen.

Autosomal Dominant (Adult) Polycystic Kidney Disease

Bilateral, enlarged echogenic kidneys. Absent urinary bladder. Oligohydramnios. Meckel-Gruber syndrome is associated with ARPKD 3-10 times larger than normal renal size. Fetuses with Trisomy 13-18 may also have it. The cysts with ARPKD are microscopic and not identifiable.

Autosomal Recessive (infantile) Polycystic Kidney Disease

Posterior urethral valves are a common cause of bladder outlet obstructions in male fetuses. The keyhole sign is seen when there is dilation of the urinary bladder and the posterior urethra. Posterior urethral valves result in dilation of the bladder, ureters, and renal collecting system. Oligohydramnios and bladder wall thickening will be observed as well.

Bladder Outlet Obstructions and Posterior Urethral Valves

External position of the bladder

Bladder exstrophy describes;

Anomaly wherein the bladder is located outside of pelvis. The cloaca is the embryonic structure that develops into the rectum and urogenital sinus. The cloaca can be persistent and result in the combination of the urinary genitals, and intestinal tract, emptying into a common orifice located on the perineum

Bladder exstrophy;

The most common female finding. Fetal ovarian cysts may be noted in the fetal pelvis, secondary to maternal hormone stimulation. These cysts are usually benign and they resolve.

Clitoromegaly

There is omphalocele, bladder exstrophy, imperforate anus and spina bifida.

Cloacal Exstrophy also referred to OEIS complex

Normal amniotic fluid ( unilateral )

During an 18 week sonogram, multiple cysts of varying sizes are noted within the renal fossa of a male fetus. The other kidney appears to be normal. What would be the associated finding?

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Enlargement of bladder is called megacystis, whereas dilation of the ureter may be referred to as megaureter or hydroureter.

Renal agenesis

Failure of the kidneys to form is called;

Bilateral renal agenesis Abnormal facial features Pulmonary hypoplasia Limb abnormalities Intrauterine growth restriction

Features of Potter Syndrome

It can lead to distension of bladder, ureters, and renal collecting system. Urine is produced by kidneys, exits the kidneys by means if the renal pelvis, travels down the ureter, into the bladder, and exits the body via the urethra.

Fetal Urinary Obstruction

If the obstructions is at the ureteropelvic junction (The point where the renal pelvis meets the ureter) the renal pelvis and the renal will be dilated whereas the ureter and bladder will most likely remain normal.

Fetal Urinary Obstruction / Ureteropelvic Junction

If there is an obstruction at the ureterovesicular junction, the entire ureter, the renal pelvis and the renal calices will be eventually dilated and filled with urine.

Fetal Urinary Obstruction / Ureterovesicular Junction

Hydrocele

Fluid surrounding the fetal testiscle is referred to as;

Horseshoe kidneys.

Fusion of the lower poles of the kidney describes;

Polydactyly

Having more than the normal number of digits is;

Kidneys that are attached a their lower poles. Initially, the bladder is continuous with the allantois, eventually this channel closes and develops into a fibrous cord referred to as the urachus.

Horseshoe kidneys are;

the abnormal ventral curvature of the penis as a result of a shortened urethra that exists on the ventral penile shaft.

Hydrospadias;

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It is important to note that fetal pyelectasis can be a sonographic marker for Down Syndrome.

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MCDK disease is a fatal if bilateral, but fortunately, most cases of MCDK are unilateral.

The most common solide fetal renal mass which is essentially a hamartoma of the kidney. Sonographic findings; solid, homogenous mass within the renal fossa and may completely replace the kidney.

Mesoblastic Nephroma

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Most often, with unilateral renal agenesis, there is an average amount of amniotic fluid, and the prognosis is good.

MCDK or multicystic renal dysplasia. caused by an early, first-trimester obstruction of ureter. No normal functioning renal tissue present. Fatal if bilateral with absent bladder and oligohydramnios but most cases are unilateral.

Multicystic Dysplastic Renal Disease

The most common malignant abdominal mass in neonates located primarily within the adrenal gland. Adrenal glands may spontaneously hemorrhage within the fetus.

Neuroblastoma

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OEIS complex stands for Omphalocele, bladder Exstrophy, Imperforate anus, and Spina bifida.

Renal pelvis and calices

Obstruction at the level of the UPJ would lead to dilation of the;

Caused by an early renal obstruction. A ureterocele, or a severe bladder outlet obstruction can lead to bilateral obstructive cystic dysplasia. Oligohydramnios will be present. Unilateral obstructive cystic dysplasia is most often caused by a pelviureteral junction or vesicoureteral junction obstruction. Bilateral obstructive cystic dysplasia may be associated with urethral atresia or posterior urethral valves.

Obstructive Cystic Dysplasia

Renal abnormalities are the most frequent cause of it. Fetal kidneys begin to produce urine around 9 weeks. Urine comprises the greater part of amniotic fluid after 14 weeks. Inadequately functioning kidneys, or obstruction of the urinary tract, oligohydramnios will be present, and in some cases anhydramnios may occur. Consequence of oligohydramnios is pulmonary hypoplasia; underdevelopment of lungs.

Oligohydramnios;

The fetal kidneys develop within the pelvis and ascend into their normal position by 9 weeks. By the 10th week of gestation, fully functional kidneys exist. If the kidneys fail to ascend into the normal position, the result is an ectopic kidney, most often located within the pelvis. The testicles move down into the scrotum during the seventh month of gestation.

Pelvic Kidney

Typically caused by megacystis, a massively dilated urinary bladder. Seen mostly in males. The triad of absent abdominal musculature, undescended testis, and urinary tract abnormalities. Dilated bladder and possibly urethra (keyhole sign), hydronephrosis.

Prune Belly Syndrome

An enlarged bladder

Prune belly syndrome is caused by;

Dilation of the renal pelvis

Pyelectasis refers to;

When the kidney is absent in the abdomen, the adrenal gland can be noted in a parallel, flattened position, a sonographic finding known as the ''lying down'' adrenal sign. Bilateral renal agenesis is also known as Potter syndrome which is a fatal condition.

Renal Agenesis;

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Renal abnormalities are the most frequent cause of oligohydramnios. Therefore, if oligohydramnios is discovered, a thorough analysis of the fetal urinary tract is warranted.

Normal appearing, or bilateral, enlarged echogenic kidneys. Visible urinary bladder. Normal amniotic fluid volume. Cysts do not manifest until appx. the 4th or 5th decade of life

Sonographic Findings of ADPKD

Small, echogenic kidneys. Peripheral renal cysts. Bilateral hydronephrosis. Thick walled urinary bladder. Oligohydramnios.

Sonographic Findings of Bilateral Obstructive Cystic Dysplasia;

Lower abdominal wall mass inferior to the umbilicus. Absent urinary bladder. Normal Kidneys.

Sonographic Findings of Bladder Exstrophy

Keyhole sign (dilated bladder and urethra) Bilateral hydroureter. Bilateral hydronephrosis. Oligohydramnios. Thickened bladder wall.

Sonographic Findings of Posterior Urethral Valves

Hydronephrosis ( dilated renal pelvis and calices) Normal ureters (nonvisualization) Normal bladder.

Sonographic Findings of Ureteropelvic Junction Obstruction

Bilateral, smooth walled, noncommunicating cysts of varying sizes located within the renal fossa. Absent urinary bladder Oligohydramnios

Sonographic findings of Bilateral MCDK

Absent kidneys. Absent urinary bladder. Severe oligohydramnios or anhydramnios. Bilateral lying down adrenal signs. Undetectable renal artery branches with color doppler.

Sonographic findings of bilateral kidney agenesis;

Unilateral, smooth walled, noncommunicating cysts of varying sizes located within the renal fossa. Compensatory hypertrophy of the contralateral kidney. Visible urinary bladder. Normal amniotic fluid volume.

Sonographic findings of unilateral MCDK

Absent kidney. Compensatory hypertrophy of the contralateral kidney. Visible urinary bladder Normal amniotic fluid volume Unilateral lying down adrenal sign Undetectable renal artery branch with color doppler

Sonographic findings of unilateral kidney agenesis;

Urethral atresia. Prune belly syndrome Posterior urethral valves.

The ''keyhole'' sign would be seen in all of the following situations;

Renal agenesis

The ''lying down'' adrenal sign describes the sonographic findings of;

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The ''lying down'' adrenal sign is associated with renal agenesis.

unilateral renal agenesis bilateral renal agenesis potter syndrome

The ''lying down'' adrenal sign would be seen in all of the following ;

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The Ureteropelvic Junction, ureterovesicular junction and the urethra are the three most common areas where obstruction occurs.

Ambiguous genitalia

The birth defect in which the sex of the fetus cannot be determined defines;

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The fetal urinary bladder normally fills and empties once in every 30-45 mins

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The kidneys can be sonographically seen as early as 11 weeks endovaginally, 12 weeks with transabdominal. The fetal bladder can be seen as early as 12 weeks and should always be seen by 15 weeks.

Pelvis

The most common location of an ectopic kidney would be;

Neuroblastoma.

The most common malignant adrenal pediatric tumor is the;

Duplex collecting system, also referred to as a duplicated or double collecting system. Upper pole moiety & lower pole moiety.

The most common renal anomaly is the;

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The most common solid fetal renal mass is the mesoblastic nephroma.

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The most worrisome consequence of oligohydramnios is pulmonary hypoplasia, or underdevelopment of the lungs.

ADPD

The renal cystic disease that results in the development of cysts late in adulthood is

Meckel-Gruber syndrome

The syndrome associated with an occipital cephalocele, cystic renal disease, and polydactyly is;

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The triad of absent abdominal musculature, undescended testis, and urinary tract abnormalities is consistent with the diagnosis of prune belly syndrome.

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The urachus is located between the apex of the bladder and the umbilicus.

UPJ obstruction is the most common cause of hydronephrosis in the neonate and the most common form of fetal renal obstruction . The disease is usually unilateral and common in males. Dilation of renal pelvis and renal calices. It is important to note that fetal pyelectasis (dilation of renal pelvis) can be a marker for down syndrome.

Ureteropelvic Junction Obstruction

The least common cause of hydronephrosis. The renal collecting system and ureter will be dilated. Unilateral UVJ obstructions lead to normal amounts of amniotic fluid, bilateral obstructions lead to oligohydramnios. Hydronephrosis, dilated ureter, normal bladder, normal amniotic fluid if unilateral.

Ureterovesicular Junction Obstruction

The ureter meets the bladder.

Ureterovesicular Junction;

Vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, esophageal atresia, renal anomalies and limb anomalies.

VACTERL stands for;

An abnormal ventral curvature of the penis

What best describes hypospadias?

ARPKD (Autosomal Recessive Polycystic Kidney Disease)

What is associated with enlarged echogenic kidneys and microscopic renal cysts?

UPJ obstruction

What is the most common cause of hydronephrosis in the neonate and the most common form of fetal renal obstruction;

Mesoblastic nephroma

What is the most common fetal renal tumor?

Duplex collecting system

What is the most common renal anomaly?

Megacystis

What is the term for enlargement of the urinary bladder?

7 mm (borderline between 4 and 6 mm) after 20 weeks 10 mm (borderline between 5 and 9 mm)

What measurement should the renal pelvis not exceed prior to 20 weeks' gestation?

ARKPD

What would be the most likely cause of bilateral, enlarged, echogenic fetal kidneys and oligohydramnios?

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nonvisualization of the urinary bladder and kidneys, with associated severe oligohydramnios , is a consistent finding with bilateral renal agenesis. It can be seen in conjunction with sirenomelia.

Bilateral MCDK disease Bilateral renal agenesis ARKPD

would be associated with oligohdramnios;