A reliable method to assess cervical stiffness, towards the prediction of preterm birth

Objective To compare two methods for cervical stiffness assessment: digital palpation and a new method based on the aspiration technique.

Materials Five silicone cervix models were produced using silicone rubber gel. Different stiffnesses representative of the physiological ones were achieved by adding a softener to the material at different ratios.

Methods The stiffness of the model silicone cervices was assessed using an aspiration-technique based device by five individuals at different time points.

Subsequently, 63 healthcare professionals assessed the stiffness of each silicone cervix via digital palpation as firm, medium and soft.

Results In the digital palpation test, the participants gave equal judgement only to the softest cervix model, whereas for all the others their judgements were split among the rating possibilities. Contrarily, the maximum relative standard deviation for intra- and inter-observer variability obtained with the device was 3% and 3.4%, respectively.

Summary The results demonstrate that digital palpation is a subjective and unreliable method to assess cervical stiffness. Contrarily, the aspiration-based device can help practitioners to assess the cervical stiffness in an objective and reproducible way. We believe that this method can be safely applied in obstetric practice to predict preterm birth better than cervical length on ultrasound.

[under review]

Inter-observer variability results of the assessment of all the cervices (n=111, 105, 101, 104, 83, respectively). Blue dots represent the assessment made using the device. Pink circles indicate the percentage of participants giving the corresponding assessment (firm/medium/soft).

Publication History

Article published online:
07 October 2020