Peripheral Insertion of Umbilical Cord. (November 2013) - Luo, Guangju
Numerous studies have addressed the significance of marginal and membranous umbilical cord (UC) insertion. Recent reports suggest that an eccentrically inserted UC may also be important. This case-control study assessed the potential relevance of peripheral insertion of UC (PIUC), defined as <3 cm from the nearest margin. Singleton placentas (n = 1418) submitted to the pathology department over an 18-month period were analyzed. Each case of PIUC (n = 119) was matched with a control placenta of the same gestational age. Placentas with marginal or membranous UC and multiple gestations were excluded. The overall prevalence of PIUC was 8.4%, but PIUC frequency was significantly increased in premature births at <28 weeks (21.4%, P < 0.001). There was no association with other adverse pregnancy outcomes. PIUC was associated with decreased placental weight Z-score (−0.69 ± 0.92 versus −0.22 ± 1.3, P = 0.0056), but not fetal weight Z-score, suggesting increased utilization of placental reserve. PIUC was also associated with relatively elongated placentas (length minus width: 2.6 ± 3.2 versus 1.0 ± 3.1, P = 0.006). PIUC tended to be more frequent in young primiparous mothers and was significantly less common in women with a history of prior curettage (66% vs 50%, P = 0.013). These data, together with equivalent rates of prior cesarean section, multiparity, and advanced maternal age, support a primary developmental disorder as opposed to secondary placental migration due to underlying uterine abnormalities ("trophotropism"). Except for a borderline significant association with findings suggestive of maternal malperfusion ( P = 0.078), PIUC was not associated with other placental lesions.