Quantitative strain elastography of the uterine cervix assessed by the GE Voluson E10 system in combination with a force-measuring device

Figures & data

Figure 1. The transvaginal probe with the force-measuring device mounted on the probe handle.

Figure 2. Left, B-mode image with the elastography color box superimposed on a cervix at gestational week 38. The ROI (yellow) is placed within the anatomical area of interest within the middle third of the anterior cervical lip. The probe-centerline is marked with the white dashed line. Right, in the resulting strain curve calculated by the GE-software, the strain peak height (S_δ) is marked.

Figure 3. The force data plotted against the time with the area of a force peak (A_F), marked with green.

Table 1. Background characteristics, women with different gestational ages.

Variable	Women, N = 47, mean	95% CI
Age at inclusion (years)	31.7	30.3–33.1
Maternal pre-pregnancy BMI (kg/m^2)	25.0	23.2–26.8
Nulliparous women n (%)	27 (57%)	NA
Women smoking during pregnancy n (%)	0 (0%)	NA

Table 2. Cervical length, CEI_GE and CSI_GE in relation to the gestational age where cervical elastography index_GE (CEI_GE) and cervical strength index_GE (CSI_GE), gestational age (GA), number of pregnant women (n).

GA (week)	N	Cervical length (mm) Mean (95% CI)	CEIGE (N) Mean (95% CI)	CSIGE (N mm) Mean (95% CI)
12^+0–14^+0	9	33.3 (30.7–35.9)	0.24 (0.20–0.29)	8.2 (6.4–9.9)
19^+0–21^+0	16	35.6 (33.9–37.3)	0.25 (0.20–0.30)	8.7 (7.1–10.3)
30^+0–34^+6	5	31.3 (27.9–34.8)	0.15 (0.13–0.17)	4.7 (3.9–5.5)
35^+0–40^+0	17	29.9 (25.4–34.5)	0.19 (0.15–0.22)	5.7 (4.3–7.0)
p-value		.044	.006	.002

Statistical analysis: Test for trend.

Table 3. Background characteristics, women admitted for labor induction.

Variable	Women, N = 27, mean	95% CI
Age at inclusion (years)	31.4	30.2–32.7
Maternal pre-pregnancy BMI (kg/m^2)	25.7	23.4–28.0
Nulliparous women n (%)	19 (70%)	NA
Women smoking during pregnancy n (%)	0 (0%)	NA

Figure 4. Receiver operating characteristic (ROC) curves showing the cervical elastography index_GE (triangle) as predictor of cervical dilatation time >7 h for (A) all included women, (n = 27), and (B) nullipara (n = 19). CO (0.13) indicates the cut off giving the maximum Youden value (enlarged black triangle) [30]. (C) Cervical dilatation time from 4 to 10 cm (hours) in relation to the cervical elastography index_GE for nullipara.

Table 4. Among women undergoing induction of labor, the associations between cervical length, CEI_GE and Bishop Score and the outcomes durations of latency phase and active phase are expressed by the area under the ROC curve (AUC) with 95% CI.

	Latency phase > 24 h		Active phase > 7 h		Active phase ≤ 7 h
	All women	Nullipara	All women	Nullipara	All women	Nullipara
Long cervix	0.78 (0.59–0.98)	0.71 (0.42–0.99)			0.75 (0.53–0.99)	0.73 (0.44–1.00)
High CEIGE	0.53 (0.30–0.77)	0.51 (0.21–0.81)	0.86 (0.69–1.00)	0.94 (0.83–1.00)
Low Bishop score	0.81 (0.65–0.97)	0.70 (0.46–0.94)			0.63 (0.38–0.88)	0.56 (0.23–0.88)

Latency phase was from labor induction to 4 cm cervical dilatation. Active phase was from 4 to 10 cm cervical dilatation. CEI_GE: cervical elastography index_GE.

Schisterman EF, Perkins NJ, Liu A, et al. Optimal cut-point and its corresponding youden index to discriminate individuals using pooled blood samples. Epidemiology. 2005;16(1):73–81.

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