The Accuracy of Transabdominal Ultrasonography in Assessing Cervical Length in Comparison to Vaginal Ultrasonography at Mid-Pregnancy

Abstract

Summary P reterm birth is associated with neonatal morbidity and mortality as well as substantial health care costs. Late marriages, advanced maternal age, assisted reproductive techniques, and multiple pregnancies have contributed to the rise of the preterm birth frequency. Prophylactic progesterone supplementation and cervical length assessment for women who have had previous preterm birth are considered effective methods for preventing recurrent preterm birth. Although cervical length screening for women without previous preterm birth cannot yet be universally mandated, there is a risk associated with preterm birth even in women without previous preterm birth. However, most women not only have inconvenience during transvaginal sonography but also pay additional costs. From the point of view of physicians, transvaginal sonography takes up valuable time, and the physicians must purchase transvaginal ultrasound equipment for their medical offices. In contrast, transabdominal sonography for pregnant women requires neither additional cost nor effort because it is used for routine antenatal checkups. It is well known that many confounding factors, including the maternal physical condition and fetal position, influence the practical use of transabdominal sonography for cervical length assessment. The aim of our study was to determine the accuracy of transabdominal ultrasonography in assessment of cervical length during mid-pregnancy. The study was conducted at Ain-Shams University Maternity Hospital. Patients were recruited from the special fetal care unit who were coming for routine anomaly scan. The sample was 149 pregnant females from 20 to 24 weeks gestation. And applying the inclusion and exclusion criteria and brief history was taken the selected patients underwent cervical length assessment by transabdominal ultrasonography with full bladder. And then the patient voided the bladder and another assessment was done via transvaginal ultrasonography by another sonographer. And after that a questionnaire was answered by the patient assessing her satisfaction on the procedure. We found out the following that there is a statistical difference between both lengths measured by the transabdominal and transvaginal ultranography (Mean±SD 1.3±0.7), but in 94.7% of the patients the differences between the measurements didn`t exceed 3mm with constantly the measurements of the transabdominal were shorter. The time difference between the two procedures was significant with the transabdominal ultrasonography taking more time (Mean±SD 0.9±0.2). Most of the patients preferred the transabdominal ultrasonography over the transvaginal ultrasonography. However, we think that in spite of the statistically significant difference between the two methods of assessment, the difference did not exceed the range of (1-3 mm) of the patients and the time difference between time taken to perform the tranabominal ultrasonography and time taken to perform tranvaginal ultrasonography which was from 0.5 to 1.4mins. So, the transabdominal ultrasonography can be used to assess the cervical length during the second trimester instead of the transavaginal ultrasonography which caused discomfort to the pregnant females.