Predictive Value of First Amniotic Sac IL-6 and Maternal Blood CRP for Emergency Cerclage Success in Twin Pregnancies

Objectives: To assess the usefulness of first amniotic sac Interleukin-6 (IL-6) to rule out intra-amniotic inflammation (IAI), as well as maternal blood c-reactive protein (CRP), to select patients with a twin pregnancy who may benefit from an emergency cerclage. Materials and Methods: Retrospective, descriptive study among all patients with a twin pregnancy and mid-trimester bulging membranes admitted to a tertiary Hospital from January 2012 to September 2023. According to the Hospital's Protocol, all patients received a vaginal and abdominal ultrasound, a maternal blood test, and an amniocentesis of the first sac to rule out IAI, defined by IL-6 ≥ 2.6 ng/dL. Results: A total of 28 patients with a twin pregnancy and mid-trimester bulging membranes were included. Among them, 18 patients (64.28%) had IL-6 levels ≥ 2.6 ng/dL. Cerclage was placed in 10 patients with IL-6 < 2.6 ng/dL. Perinatal mortality in pregnancies with IL-6 ≥ 2.6 ng/dL was 77.22%. The gestational age at delivery of patients with IL-6 < 2.6 ng/dL was 34 ± 3 weeks, compared to 23 ± 4 weeks when IL-6 was ≥2.6 ng/dL (p < 0.001). The latency to delivery with IL-6 < 2.6 ng/dL was 88.1 ±31.56 days, compared to 13.11 ± 20.43 days when IL-6 was ≥2.6 ng/dL (p < 0.001). Significant differences were found in maternal blood CRP levels in both study groups (no IAI 4.32 ± 3.67 vs. IAI 13.32 ± 15.07, p < 0.05). The area under the curve with an ROC curve was 0.799 (IC 95% 0.596-0.929), with a cut-off of 3.9 mg/L (S 94.4%, % E 62.5%). The gestational age at delivery with CRP < 3.9 mg/L was 33 ± 5 weeks, while in cases with CRP ≥ 3.9 mg/L, it was 24 ± 5 weeks (p < 0.001). The latency days to delivery were 86.5 ± 44.88 and 21.95 ± 30.97 days (p < 0.01), respectively. A positive correlation between the IL-6 values of both amniotic sacs was obtained, along with the Spearman coefficient correlation rank (rho = 0.835, p < 0.001). Conclusions: Compared to those with IAI, patients with a twin pregnancy and mid-trimester bulging membranes without IAI who underwent emergency cerclage had a significantly higher interval from diagnosis to delivery, as well as a significantly lower incidence of preterm birth < 34 weeks and perinatal death. Further studies are needed to assess whether the IL-6 of the first amniotic sac and maternal blood CRP might constitute a useful parameter to select patients who may benefit from an emergency cerclage.