Gatrointestinal duplication cysts are congenital anomalies that can be associated with severe adverse outcomes, such as hemorrhage, intestinal obstruction, or intestinal torsion. Despite their substantial postnatal impact, antenatal scans have been reported to identify only 20–30% of such cases. Although the gut signature sign is considered to be relatively specific in the diagnosis of enteric duplication cysts, the classic five-layered appearance is not always easy to demonstrate in the prenatal setting. We present a case of a fetal enteric duplication cysts that presented as a migrating, peristaltic cyst prenatally with the positive ‘bilayer sign.’ Given the challenging circumstances for diagnosis, we also provide a few insights on the altering appearance of the gut signature sign and describe other practical ultrasonic features used to diagnose enteric duplication cysts.