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).
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 |