Hydatid disease is commonly encountered in specific geographic areas of the world. Hydatidosis affects multiple organs and has diverse radiologic presentations. Sonography remains an important modality for diagnosing this condition, as it optimally detects cystic structures, floating membranes, and debris. Sonography forms the crux of radiologic diagnosis of hydatid disease. It not only helps diagnose the disease but also aids in guiding therapeutic interventions. The main objective of this article is to describe the imaging features of hydatid disease in its various stages. This article gives an overview of the spectrum of sonographic manifestations of hydatid disease in various locations, along with common differential diagnoses. A brief description of therapeutic management is also presented.

We report a rare case of ectopic pregnancy occurring in the scar of a previous caesarean section, diagnosed by ultrasonography and confirmed by 3.0-T magnetic resonance imaging of pelvis. We present the clinical details and imaging findings, followed by discussion of the etiology, pathogenesis, and imaging of this condition.

Prenatal findings of a hugely dilated, hyperperistaltic large bowel should lead one to suspect/consider large bowel duplication. Associated cysts are likely to be bowel duplication cysts. Timely intervention can thus obviate potentially serious complications.

Letters to the Editor SonoAVC: a new tool in early diagnosis of patent urachus with bladder prolapse A 37-year-old primigravida was referred to our prenatal diagnosis unit at 12 weeks of gestation for further examination following an abnormal ultrasound scan. She had no significant personal or family medical history. During transvaginal two-dimensional (2D) ultrasound examination, a singleton fetus with a crown-rump length of 61 mm and nuchal translucency thickness of 1.2 mm was observed. A cystic mass of 18 × 16 mm was noted within the umbilical cord, near the cord insertion. The fetal bladder appeared as a fluid-filled structure in the pelvis with apparently normal characteristics. A patent communication between the fetal bladder and the cystic mass was not identified on 2D ultrasound. No other structural abnormalities were detected. After the initial 2D scan, we proceeded to use threedimensional (3D) ultrasound imaging (Voluson E8, GE Medical Systems, Valencia, Spain) to acquire volumetric data. Once the 3D dataset of the region of interest had been obtained, SonoAVC (Sonography-based Automated Volume Count, GE Medical Systems) software was used to further explore the cystic mass. SonoAVC allowed visualization of the cystic mass within the umbilical cord, but, more importantly, clearly showed a patent communication of the mass with the vertex of the fetal bladder (Figure 1). Furthermore, the use of SonoAVC with 3D Doppler ultrasound clearly identified the umbilical arteries running around the bladder, passing through the abdominal wall defect and surrounding laterally the cystic mass to end in the umbilical cord (Figure 2). Therefore, the diagnosis of a patent urachus with bladder prolapse was made. Follow-up ultrasonographic studies showed that the cystic mass spontaneously reduced in size until it was undetectable at 28 weeks of gestation. At 39 weeks' gestation a male infant weighing 2894 g was delivered vaginally. At initial examination an anomaly on the base of the umbilical cord with protruding mucosa was observed, from which urine was voided (Figure 3). Recovery was uneventful following excision of the patent urachus. Persistent patent urachus is a rare congenital anomaly found in 1/100 000 births 1. Urachus is the intraabdominal remnant of embryonic allantois lying between the peritoneum and transversalis fascia, stretching from the dome of the bladder to the umbilicus 2. Urachal anomalies result from failed obliteration of the urachus, creating different pathologies such as patent urachus, urachus cyst, urachal sinus or vesicourachal diverticulum 2,3. Persistent patent urachus is easily recognized at birth but is rarely diagnosed prenatally 1-6. Differential diagnoses include