MIRROR-IMAGE ARTIFACT on TVS

A 27-year-old woman was admitted to the obstetric emergency department for abdominal pain without bleeding at 8 weeks’ gestation. She had a previous uneventful pregnancy delivered vaginally at term, and an early scan performed 2 weeks before the symptoms occurred revealed an ongoing intrauterine pregnancy.

The patient underwent transvaginal sonography (MyLab 25; Esaote SpA, Florence, Italy), which showed an intrauterine pregnancy with a live embryo measuring 29 mm, consistent with a gestational age of 8 weeks 5 days. A second gestational sac with irregular and undefined boundaries containing an active embryo measuring 17 mm was depicted in the rectouterine pouch (Figure 1). Both ovaries were visualized as normal, and no pelvic free fluid collection was noticed during the scan. These findings were consistent with a diagnosis of heterotopic pregnancy.

Heterotopic pregnancy refers to the rare occurrence of both intrauterine and ectopic pregnancies usually located in one fallopian tube, cervix, or, more rarely, abdomen. Assisted reproduction techniques, tubal surgery, pelvic inflammatory disease, and the use of intrauterine devices represent the most common risk factors.1

Sonography is the mainstay for diagnosis of heterotopic pregnancy, allowing for the detection of two gestational sacs located inside and outside the uterus, respectively, and blood collection in the pelvis. In addition, clinical symptoms such as pain and genital tract bleeding can help in achieving the diagnosis.1

In this case, the patient had no risk factors for this condition, with a previous uneventful pregnancy delivered at term and no history of pelvic surgery or disease. To confirm the diagnosis, the woman was asked to fill her bladder, and transabdominal sonography was performed. Interestingly, only the intrauterine gestational sac was found, with a normal appearance of the rectouterine pouch and no ectopic pregnancy detected.

AVID

Abstract

A series of 20 cases from 2 academic institutions is presented with a characteristic imaging triad of asymmetric ventriculomegaly, a large interhemispheric cyst, and partial or complete agenesis of the corpus callosum. Most cases were initially referred as aqueduct stenosis and hydrocephalus or focal porencephaly. We describe the imaging findings that identify an abnormal or absent corpus callosum associated with a type 1 interhemispheric cyst in fetuses initially thought to have hydrocephalus attributable to aqueductal stenosis. We suggest that the acronym AVID (asymmetric ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum) may be useful in recognition of these cases. All cases presented with markedly asymmetric ventriculomegaly on initial sonography, with progressive hydrocephalus throughout gestation. Fetal magnetic resonance imaging was performed in 15 of 20 cases. Thirteen of 20 cases were identified in male fetuses. Associated fetal and postnatal abnormalities are also reported. Technological improvements in sonography and fetal magnetic resonance imaging allow improved characterization of associated intracranial anomalies in the setting of hydrocephalus. Accurate diagnosis can aid parental counseling, especially because isolated aqueductal stenosis suggests a better prognosis than hydrocephalus with anomalies. Markedly asymmetric ventriculomegaly in this series was the key to excluding isolated aqueductal stenosis and was associated with callosal malformation with a type 1a interhemispheric cyst.