Phosphorylated Insulin-Like Growth Factor Binding Protein-1 And Transvaginal Ultrasonographic Cervical Length Predicting Spontaneous Preterm Delivery in Susceptible Asymptomatic Patients

Abstract

Objective: Asymptomatic cervical changes may portend and thus predict preterm labour. In addition, chorio-decidual disruption (releasing phIGFBP-1 amongst other markers into the cervical secretions) also occurs prior to preterm delivery. Even with these known facts, there is still no standard protocol for the prediction of preterm delivery. This study, therefore, aims at determining whether phIGFBP-1 and transvaginal cervical length assessment, alone or in combination, are useful in the prediction of preterm delivery in our environment. Design: An analytical prospective cohort study. Method: Asymptomatic antenatal clients at risk for preterm delivery were recruited from 22weeks gestation, their sociodemographic characteristics and reproductive profile obtained and the cervical length estimation done using transvaginal ultrasound. At 30weeks gestation, phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) was assessed from cervical secretions and all information entered into a proforma. Patients were followed up till delivery and gestational age at delivery was noted. The ability of the tests, singly and in combination, to correctly predict preterm delivery in asymptomatic susceptible patients was determined statistically using the Statistical Package for Social Sciences (SPSS) version 22. Analysis was done using chi-square and students t-test with significance set at p<0.05. Results: Eighty-four clients were used for the final analysis. The incidence of preterm delivery was 193/1000. The commonest risk factor for preterm delivery was maternal age less than 18 or greater than 35 but a history suggestive of bacterial vaginosis was the significant risk factor. Term delivery occurred in 80.7% of these women at an average gestational age of 38.6weeks. The mean cervical length at 22-24 weeks in this study was 33.71±9.61mm. The majority of women with a positive phIGFBP-1 (82.1%) had term deliveries and similarly, majority of women with short cervices ≤ 25mm had term deliveries, with a relative risk of 0.8 and 0.83 respectively. Both tests did not significantly predict the occurrence of preterm delivery. The sensitivity, specificity, positive predictive value, and negative predictive values for cervical length and phIGFBP-1 are 18.8%, 77.6%, 16.7%, 80% and 62.5%, 31.3%, 17.9%, 77.8% (p values >0.05). The measure of agreement of both tests using the kappa statistic was 0.071. Conclusion: Cervical length measurement at 22-24weeks and use of phIGFBP-1 at 30weeks did not predict spontaneous preterm delivery in susceptible asymptomatic women in our environment.