The use of hyaluronidase enzyme in the prevention of perineal lacerations in normal birth

Many studies have been undertaken with the purpose of contributing towards the prevention of perineal trauma in normal birth. Hyaluronidase enzyme was utilized during the fifties and the sixties to prevent this trauma without harm either to the mother or the fetus. The objectives of this study were: to verify the frequency, degree and location of perineal lacerations associated with the use of hyaluronidase enzyme in normal births; to associate the perineal laceration to birth conditions and birth weight. This is a random controlled trial undertaken in 2003, at the Centro de Parto Normal [Normal Birth Center] of the Amparo Maternal Maternity Hospital, a philanthropic entity located in the city of Sao Paulo. The sample consisted of 134 women in labor without previous vaginal births, distributed in two groups of 67 women. Women assigned to Group 1 were given an injection of hyaluronidase enzyme in the perinea and women in Group 2 did not receive this injection. The results demonstrate that 56.0% of the women in labor suffered some sort of perineal laceration, being that 76.1% of these were in Group 2 (p<0.0001), with a prevalence of first degree lacerations (88.0%) and with no cases of second degree lacerations in Group 1 (p=0.049). The posterior perineal was the primary location of lacerations (74.7%), with a statistically significant difference between Groups 1 and 2 (p=0.018). As to the perineal results after birth, there was no significant statistical difference when the latter are associated to labor pains, the umbilical cord being wound around the babies' neck, the duration of the second stage of labor, height of the perineum or birth weight. Vitality was preserved among all newborns, being that the lowest scores were 8 and 9 in the first and fifth minutes, respectively. The hypothesis established by the study, that hyaluronidase enzyme injected in the perineum, during the second stage, reduces the frequency and degree of perineal lacerations in normal birth, was confirmed. The conclusion is that injection of hyaluronidase enzyme in the perineum is a simple and effective method of prevention of perineal lacerations in normal birth, with no risks for the woman and the baby