Introduction of a new index of cervical consistency with transvaginal B-mode ultrasonography.

Changes in the length and consistency of the uterine cervix during pregnancy are known to precede pre-term labor. However, cervical consistency has not been studied in depth because its objective evaluation requires special equipment. Our aim was to define a new index to evaluate cervical consistency simply and easily using B-mode ultrasonography. The cervical length-consistency index (CLCI) is defined as the ratio of the length of the cervix stretched during compression to that before compression. CLCI increases as pregnancy progresses. The CLCI values that corresponded to digital examination results of firm, medium and soft were 112.0 ± 10.0, 124.1 ± 22.4 and 153.2 ± 35.7, respectively, thus confirming the existence of a significant relationship between the index and consistency. The CLCI may be useful in predicting pre-term labor and should therefore be investigated further in larger cohorts.