Publication:

Cervical sonomorphometric evaluation of normal and preterm labour by transvaginal and transabdominal sonography

Background Preterm delivery is major cause of perinatal morbidity and mortality. Measuring cervical length (CL) with ultrasonography has become increasingly acceptable as an early diagnostic procedure in patients at risk for PTL, with transvaginal ultrasonography (TV Us) being considered as the gold standard for the CL assessment.

Methods A cohort of women with singleton pregnancies, and confirmed gestational age by first or early second trimester ultrasonography, last menstrual period & clinical assessment were selected to undergo transvaginal and transabdominal sonographic measurement of cervical length between 16 and 34 week gestation. Cervical length was first measured by transabdominal route (TAS) using a 3.5 MHz curved electronic array transducer with the patient in the supine position and with a full bladder, transvaginal sonography (TVS) was done by a 7.5 MHz probe attached to an ultrasound machine. The probe was covered with a latex condom and gel placed between the transducer and the cover and also on the surface. It was then gently inserted in the vagina to obtain a sagittal view of the cervix. Doppler measurement were taken by both transabdominal and transvaginal route.

Results Gradual decrease in cervical length is seen with advancement of gestation weeks. TA Us cervical length values are noted higher than TV Us however significance is seen only at 24 weeks and cervical width are showing gradual increase with advancement of gestation weeks without significant difference between them. The study compared the mean spectral Doppler parameters RI, PI and S/D Ratio at different weeks & observed that TV Us values are more at each gestation weeks than TA Us showing significant difference 24 weeks onwards.

Conclusions Although discrepancy in statistical significance, short cervical length, funneling and gland area are important to recognize for prediction of premature onset of labour, owing to the potential for perinatal morbidity and mortality and socioeconomic burden. Transvaginal sonography remains the dominant imaging modality for evaluation of the cervix. It is operator dependent modality so care should be taken to evaluate each morphologic character.