Effect of a perineal protection device in vacuum-assisted births—a prospective randomized controlled interventional trial

BACKGROUND

Birth tears are common after vaginal birth with a prevalence of up to 85%, especially in vaginal-assisted births. Because birth trauma can cause physical and psychological short-term and long-term maternal morbidity, it is essential to improve maternal outcomes at birth.

OBJECTIVE

This study aimed to evaluate the effect of a perineal protection device on the rate of spontaneous birth tears in the posterior compartment in vacuum-assisted births and the feasibility and safety of the device.

STUDY DESIGN

In a prospective, randomized controlled interventional trial from July 2020 to October 2022, we evaluated the application of a perineal protection device in vacuum-assisted vaginal births in a tertiary care center. A total of 1998 patients were asked to participate, and 1574 patients with singletons at ≥36 weeks of gestation gave their informed consent before birth. Ultimately, 209 were included according to a power calculation, performed in advance, with a statistical power of 80% and a significance level of 5% for an expected reduction in the rate of the primary composite outcome of 20%. The primary composite outcome was the rate of low-grade perineal and/or vaginal tears in the posterior compartment. Secondary outcomes were the rate of high-grade perineal tears and episiotomies, the feasibility of the device, and its safety for the mother and child. Descriptive statistics and a logistic regression analysis were performed in an intention-to-treat, a per-protocol, and an as-treated analysis, using SPSS, version 29.0.0.0, and R. A P value of <.05 was considered statistically significant.

RESULTS

Of the 1574 patients, 249 (15.8%) had an indication for vacuum-assisted vaginal birth, and 217 (13.8%) of those were randomized. An addition 8 patients (0.5%) were excluded because the birth ended without vacuum assistance. Of the remaining 209 patients, 105 formed the intervention group (application of the device), whereas 104 formed the control group (without application of the device). No differences in primary and secondary outcomes were found in the intention-to-treat and per-protocol analysis. In the intention-to-treat analysis, 79 patients (75.2%) in the intervention group and 73 patients (70.2%) in the control group (P=.4) met the primary endpoint. In the per-protocol analysis, the primary composite outcome was seen 53 patients (77.9%) in the intervention group and in 73 patients (70.2%) in the control group (P=.27). For the as-treated analysis, 68 of the 105 patients (65%) remained in the intervention group after exclusion of 37 (35%) patients with failed application of the device. Consequently, 141 formed the control group. In the as-treated analysis, there was also no difference in the primary composite outcome between the 2 groups (53 patients [77.9%] in the intervention group and 99 patients [70.2%] in the control group). However, within the secondary outcomes, we found a significantly lower rate of mediolateral episiotomies in the intervention group (29% vs 45%; P=.034). No adverse outcomes for the mother and child were seen. In one-third of cases, the device was difficult to place correctly and/or to keep correctly in place.

CONCLUSION

The perineal protection device was not able to reduce the primary composite outcome of the study among women who gave birth by vacuum assistance. Although this was not the primary end point, a lower rate of mediolateral episiotomies was observed when the device was used correctly. As a limitation, difficulties with the application of the device occurred in 33% of cases. Nevertheless, no adverse events in association with the device were observed for either mother or child in our cohort.