Transvaginal grey scale histogram of the cervix at 20-25 weeks of pregnancy

To assess the echogenicity of the cervical stroma and area surrounding the cervical canal (cervical gland area - CGA) using grey scale histogram (GSH) in pregnancies between 20 and 25 weeks.

Cross-sectional study involving 149 pregnancies in the second trimester. Transvaginal sonography was performed to measure cervical length (biometric evaluation), assess the CGA and detect cervical funnelling (morphologic evaluation). The GSH was used for the objective assessment of the cervical stroma and CGA in the mid portion of the cervix. Mean, minimum, maximum and standard deviation measurements were obtained on the GSH and the CGA/stroma ratio was calculated. Intra-observer and inter-observer reproducibility were assessed using the intraclass correlation coefficient (ICC).

Mean cervical length was 42.37 ± 7.05 mm (range 12-54 mm). Funnelling was detected in four women (2.7%) and one of these also had absent CGA. The mean GSH stroma value was 103 ± 25 (53-160) and the mean CGA value was 64.5 ± 23 (13-167). The mean CGA/stroma ratio was 0.62 ± 0.14 (0.24-1.29). Intra- and inter-observer reproducibility was excellent with ICC of 0.975 and 0.922 respectively.

There are large differences in the texture of the cervical stroma and CGA on GSH allowing the objective differentiation of the two areas. The CGA/stroma ratio allows the objective assessment of the absence or presence of the CGA.