Marginal placental cord insertion: the need for follow up?

The objectives of this study were (1) to estimate the association between marginal placental cord insertion (PCI) and small for gestational age (SGA) and other adverse perinatal outcomes and (2) to determine if pregnancy-associated plasma protein A (PAPP-A) levels was altered in these patients.

It was a retrospective cohort study of singleton pregnancies undergoing ultrasound between 2016 and 2018. Marginal PCI was defined as a distance of ≤2 cm from placental edge to PCI site, visualized in both sagittal and transverse planes, and diagnosed between 16 and 32 weeks. Velamentous PCI were excluded. The primary outcome was SGA, defined as birthweight below 10th percentile for gestational age. Pregnancies with marginal PCI were compared to those with normal PCI with respect to maternal characteristics, PAPP-A levels and adverse perinatal and delivery outcomes.

The incidence of marginal PCI was 4.2% (76/1819). Compared to those with a normal PCI, patients with a marginal PCI were more likely to be nulliparous and less likely to be African American or morbidly obese (p < .05). SGA rate was similar between the groups (17.6% vs. 18.1%). There was a trend toward an increased incidence of oligohydramnios, polyhydramnios and breech presentation in patients with marginal PCI; however, these did not reach statistical significance. The incidence of low PAPP-A level was comparable between the groups (18.4% vs. 14.3%, p > .05).

Our study did not demonstrate any increase in adverse pregnancy outcomes in the presence of marginal PCI. These findings may provide reassurance for counseling patients with this sonographic finding.