Marginal cord insertion

Marginal cord insertion is a type of abnormal cord insertion.

Epidemiology

The estimated incidence is at ~7% ¹ of singleton pregnancies but ~25% of twin pregnancies. Hence, it is very important to locate the umbilical cord in all patients, particularly in high-risk pregnancy.

Pathology

In this situation, the cord insertion is too close to the placental margin (usually defined as <2 cm ⁵ although some references define it as <1 cm ^3,6)

Associations

• monochorionic twins pregnancy
• intrauterine growth retardation (IUGR)
• preterm birth ⁷

Some authors state that there is no increased risk ⁵.

Treatment and prognosis

Progression into a velamentous cord insertion as a result of "placental trophotropism" can be seen in later stages of pregnancy. Second-trimester marginal cord insertion can be associated with increased likelihood for low birth weight, pre-term delivery and composite adverse obstetrical and neonatal outcomes ⁸.