Introduction: The purpose of this study was to compare the frequency and severity of perineal trauma during spontaneous birth with or without perineal injections of hyaluronidase (HAase).
Methods: A randomized, placebo-controlled, double-blind clinical trial was conducted in a midwife-led, in-hospital birth center in São Paulo, Brazil. Primiparous women (N = 160) were randomly assigned to an experimental (n = 80) or control (n = 80) group. During the second stage of labor, women in the experimental group received an injection of 20.000 turbidity-reducing units of HAase in the posterior region of the perineum, and those in the control group received a placebo injection. The assessment of perineal outcome was performed by 2 independent nurse-midwives. A 1-tailed Fisher exact test was performed, and a P value < .025 was considered statistically significant.
Results: Perineal integrity occurred in 34.2% of the experimental group and in 32.5% of the control group, which was not a statistically significant difference (P= .477). First-degree laceration was the most common trauma in the posterior region of the perineum in women in both groups (experimental = 56%, control = 42.6%). Severe perineal trauma occurred in 28.9% of the experimental group and 38.8% of the control group, which also was not a statistically significant difference (P= .131). The depth of second-degree perineal lacerations in the experimental and control groups, measured by the Peri-Rule, was 1.9 cm and 2.3 cm, respectively. An episiotomy was performed in 11 women (experimental group = 3, control group = 8), and 4 (all in control group) had third-degree lacerations.
Discussion: The use of injectable HAase did not increase the proportion of intact perineum and did not reduce the proportion of severe perineal trauma in our sample.