The choroid plexus pseudocyst: sonographic identification and characterization

Amniocentesis has been advocated by some authors when fetal choroid plexus cysts are discovered, because of their reported association with karyotype abnormalities. We have noted an oval hypoechoic structure projecting into the adjacent choroid plexus, which simulates a cyst when imaged across its short axis, in 39 of 50 consecutive fetuses. This presumably normal structure or pseudocyst may represent the corpus striatum. Knowledge of its existence and benign nature will help avoid diagnostic errors and unnecessary amniocenteses.