The risk of anticipated delivery in asymptomatic women presenting with short cervix in early viability

While it is known that an asymptomatic short cervical length (CL) is an independent risk factor for spontaneous preterm birth (sPTB), it is unclear when the delivery will take place. Subsequently, management decisions such as timing of antenatal corticosteroid (ACS) administration or hospital admission may be suboptimal. Therefore, the purpose of this study was to determine the risk of anticipated delivery in asymptomatic women presenting with a short CL in early viability. A retrospective cohort study of asymptomatic women with short cervix, (CL ≤ 25mm) between 23 and 28 weeks’ gestation, at a single center from January 2015 to March 2018 was performed. Women with multiple gestations, fetal anomalies and cervical cerclage were excluded. Demographic information as well as risk factors for sPTB were collected. Cases were divided into 4 groups based on CL measurement (≤ 10mm, 11-15mm, 16-20mm, 21-25mm). The primary outcome was time interval from presentation to delivery (Δt). Secondary outcomes included delivery within 2 weeks of presentation and gestational age (GA) at delivery. Continuous variables were compared using the Kruskal-Wallis test, while categorical variables were compared using Chi-squared or Fisher’s exact test as appropriate. The Wilcoxon test for difference in survival time was used to compare GA at delivery among the 4 CL groups with data stratified based on GA at presentation. 126 pregnancies met inclusion criteria. Baseline characteristics were similar among all four groups. Primary and secondary outcomes are reported in Table 1. The probability of delivery as a function of Δt is presented in Figure 1. There was a direct correlation between shorter CL and shorter Δt (p = 0.003). Regardless of the CL at presentation, delivery within 2 weeks was uncommon (1 patient; 0.8%). As expected, the risk for sPTB in asymptomatic women with short cervix increases as the CL shortens, with CL ≤10mm associated with the highest risk. Nevertheless, regardless of the CL, delivery within 2 weeks is highly unlikely. Therefore, we suggest that the timing of administration of ACS in this population should be delayed until additional indications are present.View Large Image Figure ViewerDownload Hi-res image Download (PPT)