A 23-year-old G3P2 with unremarkable history was sent to our department at 32nd week of pregnancy due to a cerebral cystic structure. The course of pregnancy was without problems and biochemical triple test was negative. Our ultrasound investigation revealed dilated cerebral ventricles with interhemispheric arachnoid cyst extended to the right hemisphere. A two vessel cord was also visible. The MRI was performed and confirmed our diagnosis.

Here are some of the images we obtained.

Images 1, 2: 2D sonography; 32 week of pregnancy; transverse planes through the fetal skull showing dilated third ventricle and dominant interhemispheric cyst extending to the right.

Images 3, 4: 2D sonography; 32 week of pregnancy; coronal planes through the fetal skull showing dilated lateral ventricles and interhemispheric cyst extending to the right.

Images 5, 6: Color Doppler (image 5, left) and 2D sonogram showing two vessel umbilical cord.

Images 7: 3D image - normal fetal face.

Images 8, 9: MRI; 32 week of pregnancy; transverse sections through the fetal skull showing dilated lateral ventricles and dominant interhemispheric cyst extending to the right.

Images 10, 11: MRI; 32 week of pregnancy; transverse (image 11, left) and parasagittal (image 12, right) sections through the fetal skull showing dilated lateral ventricles and interhemispheric cyst.