Preoperative inflammatory, thromboelastographic, and lower-genital-tract screening findings associated with preterm delivery after cervical cerclage: a retrospective cohort study

Objective To examine whether preoperative neutrophil-to-lymphocyte ratio, thromboelastography-derived coagulation index, vaginal cleanliness, and genital mycoplasma culture results were associated with delivery before 37 weeks after transvaginal cervical cerclage. Methods This single-center retrospective cohort included 135 singleton pregnancies that underwent transvaginal cerclage from September 2019 through December 2023. The exposure variables were the neutrophil-to-lymphocyte ratio (NLR), thromboelastography (TEG) coagulation index (CI), abnormal vaginal cleanliness defined as grade III–IV, and positive genital mycoplasma culture. The primary outcome was delivery before 37 completed weeks. Gestational age in days was used as the time scale in delayed-entry Cox regression, with entry on the day of cerclage and administrative censoring at 37 weeks. The fully integrated Cox model adjusted for maternal age, gestational age at cerclage, conception mode, and cerclage type. Delivery before 34 weeks and delivery before 32 weeks were examined using Firth logistic regression. Results Delivery occurred before 37 weeks in 53 women (39.3%), before 34 weeks in 24 (17.8%), and before 32 weeks in 16 (11.9%). In the fully integrated delayed-entry Cox model, higher NLR [adjusted hazard ratio [HR] per unit 1.22, 95% confidence interval [CI] 1.07–1.40], higher TEG CI (adjusted HR per unit 1.21, 95% CI 1.03–1.42), and abnormal vaginal cleanliness (adjusted HR 2.10, 95% CI 1.07–4.13) were associated with delivery before 37 weeks. Positive genital mycoplasma culture was not independently associated with the primary outcome (adjusted HR 1.16, 95% CI 0.64–2.12). Adding NLR and TEG CI to the clinical model improved model fit (likelihood-ratio P < 0.001), whereas the further addition of vaginal cleanliness and Mycoplasma culture did not produce statistically significant improvement ( P = 0.092). The associations of NLR and TEG CI remained similar in sensitivity analyses, whereas the association with abnormal vaginal cleanliness was attenuated when the analysis was restricted to cerclage performed at or before 26 weeks. Greater ultrasound-measured internal cervical os width, higher NLR, and higher TEG CI were associated with delivery before both 34 and 32 weeks in adjusted Firth models. Conclusion Higher preoperative NLR, higher TEG coagulation index, and abnormal vaginal cleanliness were associated with delivery before 37 weeks after transvaginal cervical cerclage, whereas positive Mycoplasma culture was not independently associated with the outcome. Given the single-center design and limited number of events, these findings should be considered exploratory and require confirmation in larger prospective studies.