Table 2.

Sonographic and Compositional Measures of the Cervix

GA of Rat	n	SD, μm*	AC, dB/mm3†	SSF, dB/mm3‡	Hydroxyproline/Cervix, %§	Hydroxyproline/Cervix, μg/mg||	Water/Cervix, %	Ratio of Collagen Pixels¶
Nonpregnant	13	10.4 (0.6)#	−118 (6)#**	2.8 (1)#**	0.88 (0.1)#**	568 (75)#**	68 (5)	0.83 (0.3)
Day 15	13	8.2 (1.3)#**	−130 (7)**	−1.5 (1)	0.72 (0.1)#**	532 (83)**	69 (8)	0.69 (0.3)
Day 17	13	11.2 (0.8)#	−144 (7)#	−2.3 (2)	0.68 (0.1)	603 (103)	68 (5)	0.61 (0.2)
Day 19	13	8.6 (1.2)	−130 (5)**	−1.2 (1)	0.62 (0.1)#	605 (75)#	69 (6)	0.69 (0.2)
Day 20	13	8.8 (1.0)	−136 (8)	−2.2 (2)	0.64 (0.1)#	640 (131)#	69 (4)	0.58 (0.2)
Day 21	13	10.0 (1.7)#	−141 (11)#	−2.7 (2)	0.62 (0.1)#	707 (153)#	68 (6)	0.70 (0.3)
Statistic		F5,72 = 10.72; P < .0001	F5,72 = 19.47; P < .0001	F5,72 = 26.47; P < .0001	F5,72 = 107.45; P < .0001	F5,72 = 4.09; P < .003	F5,72 = 0.24; P = .24	F5,72 = 1.6; P = .17

Values are expressed as mean (standard deviation)

^*Scatterer diameter = correlational length of the scatterer; differences among groups.

^†Acoustic concentration = number of scatterers/mm³ − (average impedance of scatterers)².

^‡Scatterer Strength Factor = AC × (average radius of scatterers)⁶.

^§Concentration of hydroxyproline per cervix, wet weight.

^||Content of hydroxyproline per total cervix, wet weight.

^¶Ratio of collagen-stained pixels compared with stained cells (smooth muscles and white cells) per digital histologic slide at ×20 magnification.

^#**Tukey post hoc tests to determine between-group differences:

^#P < .01 versus day 15 group;

^**P < .01 versus day 21 group.