Ultrasound and alternative multimodality imaging of intra-abdominal and pelvic cystic masses in the newborn.

Ultrasound is used commonly to detect and diagnose intra-abdominal and pelvic cystic masses in the newborn as it is easily available, relatively low cost, and non-invasive. The diagnosis can be made or narrowed down by determining the location, size, sonographic features, organ involvement, and internal vascularity. The differential diagnoses include hydronephrosis, multicystic dysplastic kidney, adrenal haemorrhage, cystic teratomas, ovarian cysts, enteric cysts, meconium cysts, and liver haemangiomas. With the appropriate radiological knowledge, the ultrasound practitioner can help obtain an accurate diagnosis. This pictorial essay will familiarise the reader with the different common causes of intra-abdominal and pelvic masses detected on ultrasound through a wide range of conditions. The role of ultrasound in the evaluation of these conditions will be discussed and alternative imaging correlates will be offered.