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Table 4 Prediction of time to onset of labour > 12 hours by the Bishop Score vs. cervical resistivity (CR) measured with a 12 mm probe (data shown for 4 frequencies 9.8-78.1 kHz).

From: The role of cervical Electrical Impedance Spectroscopy in the prediction of the course and outcome of induced labour

  Correlation coefficient AUC (95% CI) Optimal cut-off value Sensitivity (95% CI) Specificity (95% CI) +LR -LR PPV(%) NPV (%)
Bishop score -0.620** 0.85 (0.80-0.90)** ≤ 5 87.9 (77.5 - 94.6) 67.7 (58.8 - 75.9) 2.72 0.18 59.2 91.3
Frequency of CR          
9.8 kHz 0.044 0.53 (0.45-0.60) >1.69 Ω.m 95.2 (86.7 - 99.0) 18.03 (11.7 - 26.0) 1.16 0.26 37.5 88.0
19.5 kHz 0.029 0.52 (0.45-0.59) >2.29 Ω.m 46.03 (33.4 - 59.1) 64.75 (55.6 - 73.2) 1.31 0.83 40.0 70.0
39.1 kHz 0.033 0.48(0.40-0.55) >2.15 Ω.m 49.21 (36.4 - 62.1) 61.5 (52.2 - 70.1) 1.28 0.83 39.7 70.1
78.1 kHz 0.013 0.51(0.44-0.59) >2.53 Ω.m 26.98 (16.6 - 39.7) 81.97 (74.0 - 88.3) 1.50 0.89 43.6 68.5
  1. CR cervical resistivity, AUC Area Under the ROC Curve, LR Likelihood ratio, PPV positive predictive value, NPV negative predictive value, ** P < 0.01