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Prematurity

Poster Session 2

(730) Vaginal progesterone treatment failure in otherwise low-risk patients with short cervix

Tuesday, February 13, 2024
3:30 PM – 5:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Foundation Awardee
Objective: Although vaginal progesterone is recommended for treatment in otherwise low-risk patients with cervical length (CL) ≤25mm, the data are limited on failed treatment, defined as the need for cerclage placement, cervical dilation, or spontaneous delivery prior to 24 weeks, particularly for the highest risk subgroup with CL ≤10mm.

Study Design: This is a retrospective cohort study (2016-2022) at a single institution of individuals with singleton pregnancies, no history of spontaneous preterm birth, and started on vaginal progesterone for CL of ≤25mm between 16-24 weeks. The primary outcome was cerclage placement, cervical dilation, or spontaneous delivery prior to 24 weeks. Planned subgroup analysis was performed for those with CL ≤10mm. Baseline and sonographic characteristics were compared using chi-square, Fisher’s exact, t-test, or Wilcoxon rank sum test as appropriate. Kaplan Meier survival curves were used to depict time to treatment failure stratified by CL ≤10mm.

Results: Of 162 patients who met inclusion criteria, 41 (25.3%) failed treatment defined as cerclage placement (N=39), cervical dilation (N=16), or spontaneous delivery prior to 24 weeks (N=5). Baseline demographic characteristics were similar between groups. The relative risk of treatment failure for those with CL ≤10mm was 4.07 [2.61, 6.35] compared to those with CL >10mm. Individuals who experienced treatment failure were more likely to have initial sonographic findings of cervical funneling (81.6% vs 30.6%, p< 0.001), changes with Valsalva (46.7% vs 10.6%, p< 0.001), and dynamic changes (43.8% vs 18.8%, p=0.009) at their initial ultrasound diagnosing short cervix. Gestational age at diagnosis of short cervix did not differ between groups. Approximately 75% of patients with cervical lengths ≤10mm experienced treatment failure within 3 weeks of their initial short cervix ultrasound.

Conclusion: In otherwise low-risk patients with a short cervix on vaginal progesterone, the risk of cerclage placement, cervical dilation, or pregnancy loss prior to 24 weeks is significant (25%) and approaches 75% in patients with cervical length ≤10mm.