Ovarian cysts are common in the neonatal period, likely secondary to in utero hormone exposure [22]. They may be diagnosed on prenatal ultrasound, or present symptomatically with pain, abdominal distension, or fever—usually as a result of torsion or hemorrhage. Sonography of ovarian cysts (Fig. 11.3) usually demonstrates a simple cyst with no internal echoes, and a thin wall. If there has been torsion or hemorrhage, the inner part of the cyst will contain echogenic debris. Doppler ultrasound may differentiate a hemorrhagic cyst from other ovarian neoplasms, as the latter would demonstrate internal flow. Ovarian torsion may be demonstrated by the whirlpool sign , which represents the twisted pedicle of the ovary [14]. Doppler flow to the ovarian parenchyma may be absent (Fig. 11.4) but this absence should not be used to rule out torsion since some studies have demonstrated Doppler flow in up to 50 % of torsed ovaries. Simple cysts that are less than 4 cm and have no solid component may be monitored with serial ultrasound examinations [16]. Removal of cysts is generally reserved for large, symptomatic, or torsed cysts.

Neuroblastomas are tumors derived from neural crest cells, and have an incidence of 1:10,000 live births in the USA. Advances in prenatal ultrasound have increased the prenatal detection of neuroblastoma. Furthermore, screening ultrasound in early neonates may also reveal adrenal masses, such that 30 % of neuroblastomas may be diagnosed in the neonatal period [9]. It was unknown if some of the early detection of these lesions was merely a result of increased sensitivity of the screening ultrasound, and therefore not clinically significant. Indeed, ultrasound screening performed in Japan and Quebec has demonstrated that many of these small lesions will regress spontaneously [12]. Such screening has been discontinued as the lesions detected early were low-staged tumors and the program did not alter the overall survival in the entire cohort. Ultrasound findings of neuroblastoma tend to vary with the stage of the tumor. In lower-stage tumors, ultrasound reveals a homogeneous or slightly heterogeneous solid mass that replaces the adrenal gland . At more advanced stages, this mass tends to have a much more heterogeneous echotexture, increased vascularity, and multiple intralesional calcifications [1]. All patients with neuroblastoma should receive a staging CT and a metaiodobenzylguanidine (MIBG) scan to determine the extent of involvement. Treatment is based on tumor stage, and certain neuroblastomas (4S) may be followed with serial ultrasound or CT to determine regression and need for surgery.

Hemangioma is the most common benign liver mass in infants and children, with a peak presentation between 3 and 6 months of age [5]. Presenting signs and symptoms range from a palpable abdominal mass to congestive heart failure and thrombocytopenia as a result of Kasabach–Merritt syndrome. Sonography will demonstrate a complex, solid mass with heterogeneous echotexture (Fig. 11.7) and robust Doppler flow. Infantile hemangiomas typically increase in size until 9–10 months of age, and then slowly involute [6]. Medical therapies for those that do not involute spontaneously include the use of propranolol and corticosteroids. Embolization or surgical removal is reserved for those that do not involute with medical therapy, or for patients with severe complications.

Malignant tumors comprise the majority of hepatic masses in children, with the most common tumor being hepatoblastoma [5]. Hepatoblastoma typically presents in children between the ages of one and three as a palpable abdominal mass. Initial ultrasound evaluation typically shows a well-defined, heterogeneous tumor often with cystic areas caused by necrosis and calcifications. Use of a high-frequency (> 7 MHz) linear transducer will aid in the evaluation of portal and hepatic venous involvement. The tumor may invade the venous system, or cause the formation of an echogenic tumor thrombus within the lumen of the vessels. The intraluminal material may be examined with Doppler sonography, and if there is arterial flow within the intraluminal material, venous invasion by the tumor is likely.