Reproducibility and usability assessment of the novel Fine Birth device for threatened preterm labor diagnosis

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Preterm delivery is considered the leading cause of mortality worldwide in children under five. Forty-five million pregnant women are hospitalized yearly for Threatened Preterm Labor (TPTL). However, only 50% of TPTLs end in delivery before the estimated date, classifying the rest as false TPTL. The ability of current diagnostic methods to predict TPTL is low (low positive predictive value), ranging between 8-30%. This highlights the need for a solution that accurately detects and differentiates between false and real TPTLs in women who attend obstetric clinics and hospital emergency departments with delivery symptoms. This is a pilot study aiming at first, to assess the reproducibility and usability of a novel medical device, the Fine Birth, aimed at accurately diagnosing TPTL through the objective quantification of pregnant women's cervical consistency. Secondarily, we aimed to evaluate the impact of training and the incorporation of a lateral micro camera on the device's reliability and usability outcomes. 77 singleton pregnant women were recruited during their follow-up visit to the obstetric and gynecological departments at five Spanish hospitals. Eligibility criteria were: pregnant women ≥ 18 years old, with a normal fetus and uncomplicated pregnancy, without prolapse of membranes, uterine anomalies, previous cervical surgery or latex allergy, and signing the informed written consent. Cervical tissue stiffness was assessed using the Fine Birth device, whose technology is based on the propagation of torsional waves through the studied tissue. Cervical consistency measurements were taken for each woman until obtaining two valid measurements by two different operators. The intra-observer and inter-observer reproducibility of the Fine Birth measurements was assessed using the Intraclass Correlation Coefficients (ICC) with a 95% confidence interval (CI) and the F-test p-value. The usability was evaluated based on clinicians' and participants' feedback. There was a good intra-observer reproducibility (ICC=0.88, 95% CI 0.84 to 0.95; F-test p-value < 0.05). Since the results obtained for the inter-observer reproducibility did not reach the desired acceptable values (ICC<0.75), a lateral micro camera was added to the Fine Birth intravaginal probe, and the operators involved in the clinical investigation received the corresponding training with the modified device. Analysis of 16 additional subjects demonstrated an excellent inter-observer reproducibility (ICC=0.93, 95% CI 0.78 to 0.97) and a clear improvement after the intervention (p<0.0001). The robust reproducibility and usability results obtained after the insertion of a lateral micro camera and the corresponding training make the Fine Birth a promising novel device to objectively quantify the patient's cervical consistency, diagnose TPTL and thus, predict the risk of spontaneous preterm birth. Further research is needed to demonstrate the clinical utility of the device.