Spontaneous Disappearance of Filar Cysts Diagnosed by Transabdominal Ultrasonography: A Report of Three Cases

Filar cysts (FCs) can be detected using ultrasound before or after delivery. They usually present as anechoic structures with a clear boundary just caudal to the lower end of the conus medullaris. They are generally considered a physiological variation and do not affect health. Some studies have pointed out that FCs in children can disappear spontaneously, as identified by ultrasound or magnetic resonance imaging. Three cases of FCs diagnosed by prenatal transabdominal ultrasound were reported in this study, and it was observed that FCs could disappear spontaneously in utero. The shortest time of disappearance was 4 weeks.