Pediatric Imaging Conditions

Pediatric Conditions & Considerations

• This topic covers pediatric conditions and considerations, specifically focusing on imaging techniques and abnormalities in the pelvis.

Outline

• Sonographic techniques
• Review of normal anatomy
• Ovarian abnormalities
• Uterine and vaginal abnormalities
• Infections

Sonographic Technique

• Sonography is the primary modality for evaluating the pediatric pelvis.
• Transabdominal or transvaginal scans are used, with transvaginal scans used in sexually active adolescents or older teens.
• Higher frequency transducers (up to 9 MHz for transabdominal scans) are often used.
• Linear transducers are common.
• Patient preparation includes ensuring the patient has a full bladder (may require catheterization in infants), bowel preparation, and hydration.
• Potential findings include bowel, peritoneum, and superficial lesions.

Pediatric Anatomy

• Uterus: Newborn uterus is typically 3.5 cm, prepubescent is 2.5-3 cm and postpubescent 5-8 cm. The newborn uterine endometrium is thick due to maternal hormonal stimulation. Prepubescent endometrium is thin. Postpubescent endometrium goes through cyclic changes.
• Ovaries: Ovarian volumes vary by age. Neonates have larger volumes than older children.
  • 0-5 years old: ~1 mL
  • 6-8 years old: ~1.2 mL
  • 9-10 years old: ~2.1 mL
  • 11 years old: ~2.5 mL
  • Menstruating: up to 9.8 mL

Pediatric Ovaries

• Ovaries may not be visualized due to patient size, age, or location.
• Ovaries are located between the lower pole of the kidneys and the true pelvis in neonates.
• Ovaries often appear heterogeneous in neonates due to factors like a long pedicle and a small pelvis.
• Small cysts may be seen.

Ovarian Abnormalities

• Ovarian cysts are more common than previously thought, often intra-abdominal in location in newborns.
• Cysts associated with cystic fibrosis and congenital juvenile hypothyroidism.
• Abdominal ovarian cysts can be differentiated from mesenteric or omental cysts.
• Common cyst types include follicular (>3 cm), corpus luteum, hemorrhagic, and parovarian cysts.
• Some cysts can be detected prenatally during the second and third trimester.

Ovarian Torsion

• Can occur in normal ovaries but is more common in ovaries with a mass.
• More prevalent in children.
• Fallopian tubes are relatively longer.
• Ovaries are more mobile.
• Symptoms include acute lower abdominal pain, nausea, vomiting, and leukocytosis.
• Sonographic Appearance: Ovarian enlargement, pelvic fluid, ovarian mass, and sometimes a whirlpool sign. Doppler ultrasound isn't always reliable. Multiple follicles (8-12mm) in the periphery of an enlarged ovary might indicate vascular congestion, and a possible torsion.

Partial / Intermittent Torsion

• Characterized by massive ovarian edema, marked ovarian enlargement, and a solid, hypoechoic mass.
• There is enhanced transmission through the area due to compromised venous and lymphatic drainage.
• Ovaries can enlarge up to 35 cm.
• Refer to specific chapters (e.g., Chapter 54 in Rumack) for further information.

Ovarian Neoplasms

• Account for 1% of childhood tumors and 10-30% of all malignant tumors.
• Common during puberty
• Often present with abdominal pain and palpable mass.
• May undergo torsion or hemorrhage.
• In children under 10, 84% of germ cell tumors are malignant.
• Germ cell tumors account for 60% of ovarian neoplasms. 75-95% of germ cell tumors are benign teratomas.
• Types include teratoma, dysgerminoma, cystadenoma/cystadenocarcinoma, granulosa-theca cell tumor (precocious puberty), and arrhenoblastoma (masculanizing effects).

Leukemic Infiltration

• Ovaries are a common site for acute leukemia.
• Ovarian involvement can occur in up to 50% of cases.
• Large hypoechoic pelvic masses with smooth, lobulated margins are common findings.
• THe tumor can infiltrate pelvic organs, thus making uterus and ovaries difficult/impossible to diagnose.

Pediatric Cancer Spread to Ovaries

• Ovarian involvement occurs due to spread from other cancers (e.g., neuroblastoma, lymphoma and colon carcinoma).
• Malignant tumors usually have central, low-resistance Doppler flow characteristics. Benign tumors, however, usually have peripheral, high-resistance Doppler flow characteristics.
• Non-neoplastic conditions like tubo-ovarian abscess, corpus luteum, and ectopic pregnancies can also result in abnormal Doppler flow images.

Uterine & Vaginal Abnormalities

• Congenital abnormalities such as a bicornuate uterus, hydrocolpos/hydrometrocolpos, imperforate hymen, transverse vaginal septum, or a stenotic/atretic vagina can be diagnosed.
• Congenital abnormalities found in adults can also be found in children.

Mayer-Rokitansky-Kuster-Hauser Syndrome (MRKH)

• Second most common cause of primary amenorrhea.
• Characterized by vaginal atresia, a rudimentary bicornuate uterus, and normal fallopian tubes and ovaries.
• Frequently associated with renal and skeletal anomalies. Usually unilateral renal agenesis/ectopia.

Rhabdomyosarcoma

• Most common primary malignant tumor of the uterus and vagina, but vagina is often the primary site (arising close to the cervix).
• Most frequently diagnosis occurs in children 6-18 months old.
• Presents with vaginal bleeding; tumors arise from the vaginal anterior wall and may extend into the bladder.
• Solid, homogeneous mass that fills the vaginal cavity - seen on sonograph.

Other Considerations

Pregnancy

• Pregnancy needs to be considered in children over age 9.
• Increased risk for pregnancy-related complications like toxemia, pre-eclampsia, placental abruption, lacerations, and C-sections.
• Premature labor and delivery, and perinatal mortality are higher in this group.

Foreign Bodies

• Foreign bodies, such as a wad of toilet paper, can cause vaginal bleeding/discharge, and vaginitis (4% of cases).
• Appears as an echogenic structure with distal acoustic shadowing on a sonogram, possibly indenting the posterior bladder wall.