Congenital Midline Cervical Cleft Associated With Transient Antenatal Polyhydramnios Despite Normal Prenatal Imaging: A Case Report.

Congenital midline cervical cleft (CMCC) is a rare congenital anomaly of the anterior neck, typically diagnosed postnatally based on characteristic physical findings. Prenatal detection is unlikely because the lesion is superficial and does not alter fetal anatomy or physiology in a manner detectable on routine imaging. We present a case of CMCC diagnosed after birth in a neonate whose pregnancy was notable only for transient antenatal polyhydramnios. A 27-year-old gravida 2, para 1 presented at term in spontaneous labor following a pregnancy complicated by transient polyhydramnios that resolved prior to delivery. Antenatal evaluation, including ultrasound surveillance and infectious workup, revealed no fetal structural abnormalities. The patient delivered a healthy female neonate via spontaneous vaginal delivery. Postnatal examination identified a midline anterior cervical lesion consisting of a linear cleft with a superior nipple-like projection and an inferior blind-ending sinus tract, consistent with CMCC. Imaging confirmed a superficial infrahyoid lesion without deep extension. This appears to be the first reported case of CMCC associated with antenatal polyhydramnios. This case highlights a limitation of prenatal imaging, as superficial anomalies that do not disrupt fetal physiology may remain undetected despite otherwise normal antenatal evaluation.