Tracking the trajectory- Cervical length dynamics in uncomplicated Dichorionic Diamniotic twin pregnancies: A retrospective cohort study

Objective: To study the patterns of cervical length shortening in Dichorionic Diamniotic (DCDA) twin pregnancies. Design: Retrospective cohort study Setting: Twins Clinic of a tertiary fetal medicine unit Sample population: 389 women with uncomplicated DCDA twin pregnancies Methods: For each patient, cervical length was measured at four weekly intervals. Changes in the cervical length were classified into: Pattern I: Stable cervical length, Pattern II: Early rapid shortening, Pattern III: Late shortening and Pattern IV: Early shortening with a plateau. Association of each pattern with preterm delivery was assessed. Main outcome measures: 1. To determine the patterns of cervical length shortening in DCDA twins across gestation 2. To see the association of each pattern with the risk of preterm delivery Results: Pattern 1 was observed in 37.5% cases, Pattern II in 11.8%, Pattern III in 32.6% and Pattern IV in 18%. The proportion of patients delivering preterm was highest in Pattern II, followed by Pattern III. Pattern II showed a shorter mean cervical length at both the nuchal scan and at 20–24 weeks, with a greater decline in cervical length over this period, compared with Pattern IV. Conclusion: Distinct patterns of cervical length shortening in uncomplicated dichorionic diamniotic twin pregnancies are linked to varying risks of preterm birth, thus making serial assessment more predictive than single measurements. Funding: None