Prediction of an actual birth within one week by ultrasonographic examination at 38 weeks' of gestation

Rho, Hyun Kyung; Lee, Sun Kyung; Cha, Ji Young; Cho, Tae Il; Kim, Gwang Jun

Abstract

OBJECTIVE
The aim of this study is to predict spontaneous labor onset delivery within 7 days in low risk pregnant women at 38 weeks' of gestation by ultrasonographic examination of cervical changes. MATERIAL AND METHODS: This prospective study included 110 singleton low risk pregnancies between 37(+0) and 37(+6) weeks of gestation. Fifteen cases were lost during follow-up and finally 95 pregnant women (58 nulliparous, 37 multiparous) were analysed. The study period was from Oct/2005 to May/2007. Four cervical changes (length, gland thickness, funneling and canal formation) were evaluated. Main outcome was remaining day to delivery after the examination. Remaining days to actual delivery with spontaneous labor onset were recorded and the pregnancies were divided into two groups according to remaining days (within 7 days, over 7 days) to compare predicting power of delivery within 7 days. ROC curves were drawn to find out cut-off values of cervical length and gland thickness. Sensitivity, specificity, positive predictive value and negative predictive value were extracted from four cervical changes.
RESULTS
Mean cervical length of pregnant women at 38 weeks' of gestation was 25.8 (+/-10.0) mm and mean cervical gland thickness was 4.3 (+/-1.2) mm. Funnelings of uterine cervix were detected in 13 cases (13.7%), canal formations in 6 cases (6.3%). All four cervical changes were statistically valuable to predict delivery within 7 days and the cervical length showed highest sensitivity. When the cervical length was measured under 20 mm, the possibility of delivery within 7 days was 78.6% (p<0.001). The cervical gland thickness less than 4 mm could predict the delivery within 7 days with sensitivity of 57.1% (p<0.01). Sensitivities of funneling and canal formation for delivery within 7 days were 54.5%, 36.4% each.
CONCLUSION
Ultrasonographic examination of the cervical changes in low risk singleton pregnancy at 38 weeks' of gestation are valuable for predicting spontaneous labor onset delivery within 7 days. Among four cervical changes, cervical length is most sensitive ultrasonographic marker.