Shear Wave Elastography to Assess Perineal Body Stiffness During Labor.

The objective of this study was to evaluate perineal body stiffness intrapartum using shear wave elastography ultrasound and to study its association with maternal and labor characteristics. This was a prospective observational study. Pregnant women with term pregnancy who had been admitted for labor management were recruited into the study. Transperineal shear wave elastography of perineal body was performed. Maternal and labor data were retrieved from electronic medical charts. Thirty-two patients' data were available for analysis. Mean (SD) melastography modulus was 15.33 (5.49). While comparing the mean elastography modulus across maternal and labor characteristics, the difference was statistically different between parity, cervical dilation, and perineal laceration presence groups (P < 0.05). The mean of elastography modulus of primiparous women with cervical dilation less than 3 cm was 21.47 kPa, whereas that of multiparous women was 13.17 kPa (P = 0.0511). Perineal laceration was more prevalent in women with stiffer perineal body. The risk of having perineal laceration compared with no perineal laceration was 29.1% higher for each additional unit increase in perineal body elastography modulus (odds ratio, 0.709; 95% confidence interval, 0.507-0.992). Shear wave elastography can be used to quantify perineal body stiffness. Primiparous women in early stages of labor have stiffer perineal body than multiparous women in any stage of labor and primiparous women in late stage of labor.