Persistent Cord Presentation Due to Marginal Cord Insertion at the Lower Edge of a Low-Lying Placenta: A Case of Successful Vaginal Delivery.

The position of the umbilical cord within the uterus is influenced by its insertion site, with low insertion near the internal os raising concerns regarding the risk of cord prolapse and feasibility of vaginal delivery. This report describes a case of persistent cord presentation caused by marginal cord insertion at the lower edge of a low-lying placenta, further complicated by preterm premature rupture of membranes (pPROM) at 30 weeks. Given the fetal immaturity, expectant management was pursued despite the potential risk of cord prolapse. Although persistent amniotic fluid leakage occurred, no signs of fetal compromise or immediate cervical ripening were noted. Sequential transvaginal ultrasound examinations over a period of more than one month demonstrated a gradual resolution of cord presentation, likely facilitated by placental migration and descent of the fetal head shortly before the onset of labor. This progression ultimately enabled successful vaginal delivery at 35 weeks. The case reported herein highlights the critical role of close monitoring in managing persistent cord presentation associated with low cord insertion. Our findings suggest the possibility of avoiding cesarean delivery in similar high-risk scenarios.