Cervical Length in Patients With Placenta Accreta Spectrum and Its Association With Unscheduled Delivery

Objectives To evaluate the association between cervical length (CL) and unscheduled delivery in patients with placenta accreta spectrum (PAS). Methods Retrospective cohort study of patients with suspected PAS from January 2018 to June 2024. Patients with suspected PAS underwent serial ultrasounds including transvaginal CL measurement every 4 weeks. The final CL measurement prior to delivery was analyzed. Unscheduled delivery was defined as urgent delivery prior to the scheduled date due to either bleeding or preterm contractions. A receiver operating characteristics (ROC) curve was created, the optimal CL associated with unscheduled delivery was selected, and associations and prediction analyses were performed. Results Of 102 patients, 21 (20.6%) had an unscheduled delivery. Median gestational age at unscheduled delivery was 30w5d (IQR 29w0d–34w1d), and at scheduled delivery 34w0d (IQR 33w1d–34w4d, P = 0.001). CL was shorter in patients who had an unscheduled delivery compared to those with a scheduled delivery (mean [SD] 29.9 [10.2] mm versus 36.1 [10.3] mm, P = .02). CL was shorter (31.6 [SD 11.1] mm) among patients (n = 53) having a delivery <34w0d than those (n = 49) delivering ≥34.0w0d (38.5 [SD 8.6] mm, P < .001). ROC analysis showed a CL of 30 mm as the optimal cutoff for prediction of unscheduled delivery. A significant association between CL ≤30 mm with unscheduled delivery (adjusted relative risk [aRR] 2.33, 95% CI: 1.08–5.03, P = .03) was observed after adjusting for history of spontaneous preterm birth. Conclusions In patients with PAS, a CL ≤30 mm is associated with a higher rate of unscheduled delivery and delivery ≤34 weeks.