Predicting onset of labor from echogenicity of the cervical gland area on vaginal ultrasonography at term.

BACKGROUND AND AIM

On vaginal ultrasonography, cervical gland area (CGA) gradually disappears with advancing gestation. This is attributed in part to the echogenicity of the CGA becoming equal to that of the cervical stroma. The present study aimed to assess the usefulness of echogenicity in the CGA at term for predicting the time of spontaneous onset of labor.

METHODS

The ratio of mean grayscale level (MGL) in the CGA to that in the cervical stroma (CGA/stroma MGL ratio) was estimated as an index of echogenicity in the CGA in women after 36 weeks of gestation (n=190). Using this ratio, time until onset of labor was predicted among women between 37 and 38 weeks (n=104).

RESULTS

CGA/stroma MGL ratio increased with advancing gestation, decreasing cervical length (CL), and increasing Bishop score. Univariate logistic analysis indicated that a combination of CL<20 mm and CGA/stroma MGL ratio ≥100% predicted onset of labor within a week [odds ratio (OR), 22.2; 95% confidence interval (CI), 2.4-202.0] was even better than short CL alone (OR, 6.8; 95%CI, 1.7-26.7; P=0.006). Stepwise logistic analysis identified that this combination was an only independent predictor (OR, 20.8; 95%CI, 2.3-188.5; P=0.007).

CONCLUSION

The combination of CGA/stroma MGL ratio ≥100% and short CL may offer a useful predictor of onset of labor.