New approach to the evaluation of perineal measurements to predict the likelihood of the need for an episiotomy

Abstract

Introduction and hypothesis: Episiotomy is performed selectively during vaginal delivery. Among the maternal anthropometric factors for episiotomy, the length of the perineal body (pb) and genital hiatus (gh) defined as per the POP-Q system have been studied. The objective of our study was to compare two perineal measurements (defined as per the POP-Q system and the anogenital distance [AGD] concept) to determine which of these can predict the likelihood of an episiotomy being performed.

Methods: An observational prospective cohort study was designed. Anthropometric data (pb, gh, symphysis-coccyx distance, distance between ischial tuberosities, AGDaf [anus-fourchette], and AGDac [anus-clitoris]), duration of the second stage of labor, and neonatal biometric data were collected from 119 women included in this study. Statistical analysis was performed using Student's t test for unpaired data, Mann-Whitney, and Chi-squared tests. Receiver operating characteristic (ROC) curves were generated to compare AGDaf, AGDac, and "gh + pb" with the presence of episiotomy.

Results: A shorter "gh + pb" length and AGDac were risk factors for episiotomy. Compared with AGDac, gh + pb was a slightly better predictor in ROC curve analysis. Furthermore, a longer duration of second-stage labor was evident in the episiotomy group.

Conclusions: This study introduces measures of AGD as risk factors for episiotomy. We propose that "gh + pb" length <77 mm and AGDac <93 mm may predict the likelihood of requiring episiotomy and may be useful for diminishing subjectivity in the decision to perform an episiotomy.

Keywords: Anogenital distance; Episiotomy; Perineum; Vaginal delivery.