Neonatal and Pediatric Kidneys, Adrenal Glands, and Pelvis

Flashcards covering the neonatal and pediatric kidneys, adrenal glands, and pelvis, including embryology, normal sonographic appearance, and various congenital anomalies and pathological conditions, presented in a question and answer format.

What is adrenal hemorrhage?

A condition in neonates involving bleeding within the adrenal gland.

What clinical factors predispose a neonate to adrenal hemorrhage?

Difficult delivery, large size, infants of diabetic mothers, stress and hypoxia at delivery, septicemia, and shock.

Can a newborn with adrenal hemorrhage present without associated predisposing factors?

Yes, they may still present with an abdominal mass, jaundice, and anemia.

What are common secondary complications associated with adrenal hemorrhage?

Uncontrolled bleeding, jaundice, intestinal obstruction, hypertension, adrenal abscess, or impaired renal function.

What are the sonographic findings of adrenal hemorrhage?

Ovoid enlargement of the gland or a portion, with appearance ranging from anechoic to hyperechoic or mixed echogenicities.

How does significant adrenal enlargement due to hemorrhage affect the kidney?

It produces characteristic blunting of the superior pole of the underlying kidney and inferior displacement of the kidney.

How can adrenal hemorrhage be differentiated from an adrenal neuroblastoma via sonography?

Adrenal hemorrhage decreases in size over time (within 4-6 weeks), unlike a neoplasm, and may show calcification.

What is an adrenal neuroblastoma?

A neoplastic growth originating in the adrenal gland, often with increased vascularity.

How does neuroblastoma appear sonographically in terms of vascularity compared to adrenal hemorrhage?

Neuroblastoma shows increased vascularity, while adrenal hemorrhage typically does not.

How does neuroblastoma differ from Wilms' tumor in terms of spread and characteristics?

Neuroblastoma spreads early and widely around the aorta, celiac, and superior mesenteric arteries and is poorly defined/heterogeneous with irregular hyperechoic calcifications, unlike the well-encapsulated Wilms' tumor.

What percentage of neuroblastoma patients are reported to have intraspinal extension?

As many as 15%.

Why is ultrasonography considered in the initial assessment of an infant with suspected neuroblastoma, particularly regarding the spinal canal?

Because it can successfully define the spinal canal in young infants to check for intraspinal extension.

What is the primary objective when discussing the development of ovaries and the male genital tract?

To understand their embryological origins and development.

What imaging modality is crucial for evaluating the pelvis in neonatal, pediatric, and adolescent patients?

Sonography.

What percentage of congenital uterine abnormalities occur in females?

Approximately 0.5%.

What structures serve as an acoustic window for imaging the pelvic anatomy in pediatric females?

A distended urinary bladder.

What transducer frequency range is typically used for neonatal images in pelvic sonography?

7.5 to 12 MHz.

What are the first parts of the genital system to develop?

The gonads.

From what do the gonads arise?

From parts of the urogenital ridges called gonadal ridges.

What is the mesovarium?

A mesentery developed as the gonadal ridge enlarges and frees itself from the mesonephros.

What are primary sex cords?

Cords of cells formed by the coelomic epithelium covering the gonadal ridges, growing into the mesenchyme.

Where do primordial germ cells originate?

In the wall of the yolk sac.

What happens to the primary sex cords in female embryos?

They converge to form the rete ovarii, which soon disappear along with the primary sex cords.

What are secondary sex cords, or cortical cords?

Cords that arise from the surface epithelium of the developing ovary at the same time the rete ovarii appear.

At approximately how many weeks gestation do cortical cords break up into isolated cell clusters called primordial follicles?

About 16 weeks of gestation.

What does each primordial follicle contain?

An oogonium (derived from the primordial germ cell) surrounded by a layer of flattened follicular cells.

What are oogonia?

Primitive germ cells that multiply rapidly by mitosis to produce thousands of cells.

What do oogonia enlarge to form before birth?

Primary oocytes.

In which meiotic stage do primary oocytes arrest until puberty?

The first meiotic prophase.

What two pairs of genital ducts are present during the indifferent state of sexual development?

Mesonephric ducts and paramesonephric ducts.

Which ducts develop into the female reproductive system?

The paramesonephric (Mullerian) ducts.

By which gestational week are there morphological indications of maleness or femaleness?

The 9th gestational week.

What do the cranial parts of the paramesonephric ducts form?

The uterine tubes.

What do the caudal parts of the paramesonephric ducts fuse to form?

The uterovaginal primordium (or canal), which develops into the uterus and part of the vagina.

What are sinovaginal bulbs?

Paired endodermal outgrowths induced by contact of the uterovaginal primordium with the urogenital sinus.

What does the fusion of sinovaginal bulbs form?

A solid vaginal plate.

What do the central cells of the vaginal plate break down to form?

The vagina.

What do the peripheral cells of the vaginal plate form?

The vaginal epithelium.

By which gestational week are external genitalia fully developed?

By the 12th week.

Into what do both the urethra and vagina open early in development?

The urogenital sinus, which becomes the vestibule of the vagina.

What do the urogenital folds become?

The labia minora.

What do the labioscrotal swellings become?

The labia majora.

What does the phallus become in females?

The clitoris.

What can be used if difficulty arises in obtaining a distended urinary bladder for pediatric pelvic sonography?

Catheterization and filling the bladder with sterile water.

What is the typical appearance of a normal urinary bladder wall in a pediatric patient?

Smooth and thin.

What is the maximum normal thickness of a distended bladder wall in a pediatric patient?

Less than 3 mm (mean of 1.5 mm).

What is the maximum normal thickness of an empty or partially full bladder wall in a pediatric patient?

Not greater than 5 mm.

Are distal ureters routinely visualized in pediatric sonography?

No, unless they are dilated.

How does color Doppler help visualize ureters emptying into the bladder?

It allows visualization of 'ureteral jets' as urine enters the bladder.

What is hydrosonourethrograpy used for?

To image anterior urethral abnormalities like strictures, calculi, urethral valves, diverticula, and trauma.

What information does a postvoid scan provide in pediatric pelvic sonography?

Information about bladder emptying capability and helps differentiate the bladder from a pelvic cyst by showing a change in size.

Describe the sonographic appearance of the uterus in a newborn female.

Prominent and thickened with a brightly echogenic endometrial lining.

What causes the initial size of the uterine cavity after birth?

Maternal hormonal stimulation received in utero.

What is the typical length and fundus-to-cervix ratio of a newborn uterus?

Approximately 3.5 cm in length with a fundus-to-cervix ratio of 1:2.

What shape does the uterus assume in a newborn?

Pear shape, with the cervix consuming more area than the uterus (teardrop shape).

At what age does the uterus regress to a prepubertal size and tubular configuration?

At 2 to 3 months of age.

What is the typical length and fundus-to-cervix ratio of a prepubertal uterus (after 2 months)?

2.5 to 3 cm in length with a fundus-to-cervix ratio of 1:1.

Are endometrial stripe echoes typically visualized in a prepubertal uterus?

No.

When does the uterus dramatically change shape and size, with the fundus becoming much larger than the cervix?

After the onset of puberty.

What is the typical length and fundus-to-cervix ratio of a postpubertal uterus?

5 to 7 cm in length with a fundus-to-cervix ratio of 3:1.

How does the echogenicity and thickness of the endometrial lining vary in postpubertal females?

According to the phase of the menstrual cycle.

What arteries supply the uterus?

Bilateral uterine arteries, which are branches of the internal iliac arteries.

What is the appearance of the vagina on a midline longitudinal sonogram when the bladder is very distended?

A tubular structure posterior to the bladder, in continuity with the uterine cervix, with a bright central echo from mucosal walls.

Where can the neonate ovary be found?

Anywhere between the lower pole of the kidneys and the true pelvis.

What is the formula for calculating ovarian volume?

Length × Height × Width × 0.523.

What is the mean ovarian volume for premenarchal girls aged 0-5 years?

Less than 1 cm³.

What is the mean ovarian volume for premenarchal girls aged 6-8 years?

1.2 cm³.

What is the mean ovarian volume for premenarchal girls aged 9-10 years?

2.1 cm³.

What is the mean ovarian volume for premenarchal girls aged 11 years?

2.5 cm³ (±1.3).

What is the mean ovarian volume for premenarchal girls aged 12 years?

3.8 cm³ (±1.4).

What is the mean ovarian volume for premenarchal girls aged 13 years?

4.2 cm³ (±2.3).

What is the mean ovarian volume for menstrual age females?

9.8 cm³ (±5.8).

What is the typical texture of ovarian tissue on ultrasound, and what may also be seen?

Homogeneous, but small follicles may be seen.

What is the sonographic appearance of the ovary in the neonatal period?

Heterogeneous secondary to tiny cysts.

When are larger ovarian cysts more commonly seen in female patients?

After their first year of life.

What is the blood supply to the ovary?

From the ovarian artery (originates directly from the aorta) and an adnexal branch from the uterine artery.

How has the diagnosis of congenital anomalies of the uterine cavity evolved with ultrasound?

It can now be defined with transabdominal and transvaginal ultrasound, rather than hysterosalpingography with laparoscopy.

What is sonohysterosalpingography used for in older patients?

Injection of contrast material into the uterine cavity to differentiate the cavity and septa.

What are common outcomes of developmental problems or distortion of the uterine cavity?

Infertility or spontaneous abortion.

Children with congenital anomalies of the uterus and vagina often present with what?

An abdominal or pelvic mass secondary to obstruction.

What other anomalies are highly associated with abnormalities of the uterine cavity?

Renal anomalies.

From what embryonic structures are the uterus and upper third of the vagina derived?

The embryonic Mullerian (paramesonephric) ducts.

Between which embryonic weeks must the Mullerian ducts elongate, fuse, and form lumens?

Between the 7th and 12th weeks.

What types of Mullerian abnormalities result if the ducts fail to develop correctly?

Improper fusion, incomplete development of one side, or incomplete vaginal canalization.

What should be examined if Mullerian anomalies are encountered?

The kidneys, for ipsilateral renal agenesis or morphologic abnormalities.

What is Class I Mullerian anomaly?

Segmental Mullerian agenesis or incomplete vaginal canalization (e.g., transverse vaginal septum or vaginal atresia).

What is hydrocolpos?

A fluid-filled vagina.

What is hydrometrocolpos?

A fluid-filled vagina and uterus.

What is hematometrocolpos?

A blood-filled vagina and uterus.

How might vaginal atresia present in the neonatal period?

As a large cystic pelvic-abdominal mass due to maternal hormone stimulation.

What other condition can cause findings similar to vaginal atresia, hydrocolpos, or hematometrocolpos?

An imperforate hymen.

What is Class II Mullerian anomaly?

Unicornuate uterus (long and slender, deviated to one side).

What is often apparent on the contralateral side in a unicornuate uterus?

Renal agenesis.

What is Class III Mullerian anomaly?

Uterus didelphys (complete duplication of the uterus, cervix, and vagina).

Does uterus didelphys usually require treatment or cause fertility problems?

No, it is not usually associated with fertility problems and does not generally require treatment.

How are two endometrial echo complexes best demonstrated in uterus didelphys?

During the secretory phase of the menstrual cycle when the endometrium is most prominent.

What is Class IV Mullerian anomaly?

Bicornuate uterus (a uterus with duplication of the cervix, forming a bilobed uterine cavity).

How is a bicornuate uterus typically described sonographically?

Bilobed uterine cavity with wide-spaced cavities, appearing 'heart shaped' on the transverse plane.

Under what circumstance might a rudimentary horn of a bicornuate uterus cause complications?

If an embryo implants in a noncommunicating rudimentary cavity, it may rupture at 12-16 weeks.

What is Class V Mullerian anomaly?

Septate uterus (two uterine cavities closely spaced, one fundus, sometimes two cervical canals or vaginal septum).