Obstetric perineal injuries are common in normal vaginal births and its morbidity can be significant, especially when it comes to third- and fourth-degree tears. When the anal sphincter is included, these injuries can be associated with additional morbidity including anal incontinence, pelvic pain and sexual dysfunction. 
Different interventions during the second stage of labor, including perineal massage, warm compresses and perineal management techniques have been used to prevent trauma. Moderate-quality evidence suggests that warm compresses and massage, may reduce third- and fourth-degree tears. Regarding perineal management, reviews do not show a beneficial effect of the “hands-on” over “hands-off” techniques regarding perineal trauma, or if they do, the evidence is poor due to low quality studies. (1) Despite these reviews, there is epidemiological evidence that manual protection of the perineum during the last stage of birth could decrease the incidence of obstetric anal sphincter injuries (OASIS). (2)
Episiotomy is another technique that can be used to prevent severe perineal trauma and can lower the duration of the second stage of labor in fetal hypoxia situations. Evidence shows that a selective use of episiotomy is advised, and the WHO recommends that the rate of episiotomy in an institution does not exceed 10%. (3)

In 2017 training in manual perineal protection (Viennese and Finnish maneuvers) was added to our annual course “Obstetric perineal injuries”, which is open to the labor and delivery staff of our hospital and is compulsory for midwife and gynecology interns. This course also includes training on pelvic anatomy, episiotomy and diagnosis and repair of perineal tears and OASIS. 

The aim of this study was to analyze the impact of manual perineal protection training on the percentage and degree of obstetric perineal tears and the rate of episiotomy in normal vaginal births in our hospital.

This is a retrospective observational study that compared obstetric perineal injuries in a control group that included 2494 normal vaginal births from July 2015 to December 2017 and a study group that included 1766 normal vaginal births from January 2021 to August 2023, 4 years after the implementation of manual perineal protection training. From 2018 onwards, manual perineal protection was used in every delivery assisted at our hospital.
The main outcome was OASIS incidence, which was considered when an OASIS was diagnosed by the operator attending the birth, considering as OASIS, third- and fourth-degree perineal tears. Secondary outcomes were incidence of perineal tears, intact perineum and mediolateral episiotomy (MLE). Epidemiologic information such as parity and weight of the baby at birth was also retrieved from the patient’s clinical record. 
Statistical analysis was performed with PASW statistics 18.0. Qualitative variables are expressed as absolute values and percentages. For the study of categorical variables, chi-square test was used. For all tests, a p<0,05 was considered statistically significant.
Assuming an OASIS incidence according to other studies in the control group and the intervention group of 4,4% and 1,7% respectively, with a two-sided significance of 0.05 and a power of 0.8, a total of 1270 patients would be required. (2)

We had a total of 4260 normal vaginal births, 2494 in the control group and 1766 in the study group. In both the control group and the study group there were similar percentages of women without previous vaginal births (35,7% vs 35,4%), as well as the weight of the newborn which was >3500 g in similar percentages (31,2% vs 31,6%). 
In the control group compared to the study group we observed 608 vs 585 (24,4% vs 33,1%) births with intact perineum, 841 vs 224 (33,7% vs 12,7%) births with mediolateral episiotomy (MLE) without other injuries, 54 vs 16 (2,2% vs 0,9%) women presented MLE and a low degree perineal tear (Iº or IIº), 554 vs 455 (22,2% vs 25,8%) women presented first-degree perineal tears, 411 vs 468 (16,5% vs 26,5%) were diagnosed with second-degree perineal tears and 26 vs 18 (1% vs 1%) women presented third-degree perineal tears or third-degree perineal tears and MLE (OASIS); no patients were diagnosed with fourth-degree tears.
There wasn’t a significant difference in the incidence of OASIS in both groups. In the study group there was a statistically significant increase of intact perineum (24,4% vs. 33,1%; p<0,05) and a significant decrease in the incidence of episiotomy (36,4% vs. 13,6%; p<0,05).

Four years after the implementation of manual perineal protection training, we observed an increase in the incidence of intact perineum and a decrease in the rate of episiotomy, without an increase in the incidence of OASIS, in the vaginal births of our regional hospital. We also observed an increase in the incidence of first- and second-degree tears. 
Regarding episiotomy, we managed to achieve a closer rate to the one recommended by WHO. If the aim of these technique is to prevent OASIS injuries, we clearly improved the selection of patients in need of this intervention because we achieved a lower rate of episiotomy without an increase of OASIS.
Regarding OASIS, in our sample there wasn’t a significant decrease on its incidence, but before training, in our control group incidence of OASIS was already low. As seen in other studies, we know that training in OASIS diagnosis and repair, could sometimes, increase its diagnosis, thus increasing the incidence of this injuries in samples after training.

Training on manual perineal protection could be beneficial to better assess the necessity for episiotomy as well as to increase the incidence of births with intact perineum. As for OASIS, further randomized studies should be conducted to prove the benefit of manual perineal protection training on its incidence.

Aasheim V, Nilsen ABV, Reinar LM, Lukasse M. Perineal techniques during the second stage of labour for reducing perineal trauma. Cochrane Database Syst Rev. 2017;6;CD006672
Leenskjold S, Høj L, Pirhonen J. Manual protection of the perineum reduces the risk of obstetric anal sphincter ruptures. Dan Med J. 2015 May;62(5)
Jiang H, Qian X, Carroli G, et al. Selective versus routine use of episiotomy for vaginal birth. Cochrane Database Syst Rev. 2017;2:CD000081

Continence 12S (2024) 101385
DOI: 10.1016/j.cont.2024.101385