ABSTRACT
Cervical shortening, as seen by transvaginal sonography increased concentrations of maternal salivary estriol, inflammatory cytokines in amniotic fluid, and fetal fibronectin expression in cervicovaginal mucus are all detected weeks to months before a preterm birth, providing evidence that spontaneous preterm birth is the result of a long-term process, with varying clinical manifestations and dynamics and a dilated cervix as the common terminal pathway.
Routine pelvic examination has not been shown to be predictive of preterm labor. The examination of the cervix by transvaginal sonography is more objective and has been shown to be superior to the digital examination in estimating the risk of premature birth. Thereby, the sonographic structure of the cervix (length, funneling) determines, more than any other clinical findings, the interval to the delivery.
During normal pregnancy, the pregnant woman spends part of her time in an upright position. Therefore, we have established longitudinal sonographic criteria, separate for twin and singleton pregnancies, in supine and upright positions. Up to now, we have found that the funneling in an upright position -in combination with cervicovaginal fibronectin -is the most significant sonographic parameter to predict prematurity.
In risk populations, we emphasize longitudinal examinations by transvaginal sonography to increase the chance to recognize symptoms in a reversible instead of an irreversible phase and to evaluate whether maternal postural challenge assists in predicting patients at risk for premature delivery. Transvaginal sonography is of assistance to indicate and follow any management to prevent preterm birth. Clinical trials of interventions (e.g. lifestyle changes, tocolytic treatment, different types of cerclage or vaginal pessaries), based on transvaginal sonographic findings combined with biochemical examinations (cultures, interleukins, fibronectin), are urgently needed.