Peripheral cord insertions are associated only with adverse pregnancy outcome when accompanied by clinically significant placental pathology.

OBJECTIVES: The human umbilical cord normally inserts in the central region of the placental disc. There is conflicting evidence about whether or not peripheral cord insertions (<3.0 cm from the placental edge) are associated with adverse pregnancy outcomes. The relative importance of peripheral cord insertions and pathology within the placenta in mediating adverse outcomes has not been fully established.

METHODS: Sonographic measurement of the cord insertion and detailed placental pathology was performed in 309 participants. Associations between cord insertion site, placental pathology and adverse pregnancy outcomes (preeclampsia, preterm birth, small for gestational age) were examined.

RESULTS: Ninety-three participants (30%) were identified by pathological examination to have a peripheral cord insertion site. Only 41 of the 93 peripheral cords (44%) were detected by prenatal ultrasound. Peripherally inserted cords were associated with diagnostic placental pathology (p<0.0001), most commonly with maternal vascular malperfusion, within which 85% had an adverse pregnancy outcome. In cases of isolated peripheral cords, without placental pathology, the incidence of adverse outcomes was not statistically different compared to those with central cord insertions and no placental pathology (31% vs. 18%, p=0.3). A peripheral cord with an abnormal umbilical artery pulsatility index (UA PI) corresponded to an adverse outcome in 96% of the cases compared to 29% when the UA PI was normal.

CONCLUSIONS: This study demonstrates that peripheral cord insertion often is part of the spectrum of findings of maternal vascular malperfusion disease and is associated with adverse pregnancy outcomes. However, adverse outcomes were uncommon when there was an isolated peripheral cord insertion and no placental pathology. Therefore additional sonographic and biochemical features of maternal vascular malperfusion should be sought when a peripheral cord is observed. This article is protected by copyright. All rights reserved.