Possibilities for predicting perineal birth injury

Hypothesis/aims of study. To date, intranatal injuries of the genital tract and their adverse effects on the woman’s body remain one of the most important issues in obstetrics and gynecology. Despite the improved management of childbirth, the frequency of the birth canal tissue injuries has no tendency to decrease and amounts to 10.2–39.0%. The aim of this study was to assess the possibility for predicting intranatal perineal injuries.

Study design, materials and methods. The study included a prospective analysis of 90 cases of labor through the natural birth canal based on data obtained from Ufa and Chita perinatal centers in the years 2017–2019. To determine the elasticity of perineal tissues, a perineoelastomer has been developed, which allows expressing the elasticity of the vulvar ring tissues by a special conditional coefficient. Data was processed using the IBM SPSS Statistics V25.0 software package.

Results. Based on the assessment of the obtained data, a probability coefficient of perineal injuries was developed. Its calculation is based on a nonlinear regression analysis and is expressed by the formula: T = (100 ∙ CFH) / (PAA ∙ FBD ∙ ε ∙ π), where CFH is the circumference of the fetal head at the level of visual tubercles (mm), PAA is the pubic arch angle (degrees), FBD is the distance from the front to the back of the adhesion of the vulvar ring (cm), ε is the coefficient of elastic deformation of the perineum. When the coefficient T is more than 1, perineal rupture in labor is predicted.

Conclusion. In the development of obstetric injuries of the perineum, a major role is played by the ratio of the circumference of the fetal head and the maximum perimeter of the extension of a vulvar ring, which, together with the value of the pubic arch angle and the coefficient of elastic deformation of the perineum, may be a criterion in favor of performing surgical protection of the perineum in case of a threatening rupture.