Comparison of cervical lengths using transabdominal and transvaginal sonography in midpregnancy.
OBJECTIVE
Cervical length assessment is helpful to predict and prevent preterm birth. However, transvaginal sonography is not easy to perform. The aim of this study was to investigate the relationship and discrepancies between cervical lengths measured by transabdominal and transvaginal sonography in midpregnancy.


METHODS
Transabdominal and transvaginal cervical lengths were measured in 255 pregnant women between 20 and 29 gestational weeks. The discrepancies in cervical lengths between the two methods were analyzed for the following maternal and fetal conditions: (1) vertex versus breech fetal presentation, (2) whether the fetal presenting part overlay the cervical internal os, (3) whether both the internal os and external os were visible or only the internal os was clearly visible, (4) maternal bladder filling status, (5) maternal age, (6) parity, and (7) gestational age.


RESULTS
The mean cervical lengths were not significantly different (mean ± SD, 3.88 ± 0.73 cm on transabdominal sonography and 3.93 ± 0.72 cm on transvaginal sonography; P = .129; Pearson r = 0.75). The 5th-percentile transabdominal cervical length was 26.0 mm, and the transvaginal length was 27.8 mm. There were significant discrepancies between the two methods in the cases in which a fetal presenting part overlay the internal os, in the cases in which the external os was not clearly visible, and in primiparous women. Transabdominal cervical measurements were consistently shorter than transvaginal measurements in the cases with discrepancies.


CONCLUSIONS
Transabdominal cervical length measurements are correlated with transvaginal measurements overall, and the transabdominal length is consistently shorter than the transvaginal length in cases with discrepancies. Transabdominal sonography could be used as a cervical length screening tool.
Department of Obstetrics and Gynecology, Haeundae Paik Hospital, Inje University College of Medicine, 1438 Jwa-dong, Haeundae-gu, Busan 612-896, Korea. chohj@paik.ac.kr.
Hyun-Jin
HJ
Roh
Yong Il
YI
Ji
Chul Hoi
CH
Jung
Gyun Ho
GH
Jeon
Sungwook
S
Chun
Hyun Jin
HJ
Cho
D000005:Abdomen / Q000000981:diagnostic imaging; D000328:Adult; D054791:Cervical Length Measurement / Q000379:methods* / Q000706:statistics & numerical data*; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D011247:Pregnancy / Q000706:statistics & numerical data*; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000517:prevention & control; D015995:Prevalence; D015203:Reproducibility of Results; D056910:Republic of Korea / Q000453:epidemiology; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014621:Vagina / Q000000981:diagnostic imaging; D055815:Young Adult
cervical length; preterm birth; transabdominal sonography; transvaginal sonography