The relationship between perineal size and episiotomy during delivery

Women have anatomically different perineal sizes. Different perineal sizes in primiparous women may be related to episiotomy and its consequences. The aim of this study was to investigate the relationship between perineal size and episiotomy during delivery. 376 primiparous women referred to Fatemieh Hospital in Hamadan with single pregnancies, in the first stage of labor, and with a gestational age of 37 weeks and more, out of which 372 participated in this study. Before entering the first stage of labor, they underwent perineal measurements, such as perineal body (PB), genital hiatus (GH), and anogenital area (AGD), in a forced position. Then, they were followed up for episiotomy and vaginal wall rupture until the end of the second stage of labor. Our outcome in this study was an episiotomy during delivery. The mean gestational age was 39.10±1.21 weeks, and the neonatal weight was 3107.37±42.39 g. 86.3% of women had an episiotomy, and 5.4% experienced perineal tear (laceration). Mean perineal size was 3.99±0.77, genital hiatus was 3.040±0.74, GH+PB was 7.39±1.05, and AGD was 8.49±1.22 cm. There was a statistically significant relationship between perineal body size episiotomy (P=0.011), GH+PB (P=0.003), AGD (P=0.017), neonatal birth weight (P=0.021), as well as grade 1 and 2 rupture (P<0.001). The size of GH+PB at the cut-off point of 6.25 cm and AGD at the cut-off point of 9.25 cm significantly increased the chance of performing an episiotomy. In primiparous women with a gestational age of 37 to 42 weeks, vaginal delivery, shorter perineum, vaginal hiatus, and anogenital distance significantly increased the likelihood of an episiotomy. On the other hand, performing an episiotomy significantly reduced grade 1 and 2 perineal tear rates.