Obstetric anal sphincter injuries (OASIS) are associated with numerous consequences as anal fecal incontinence, fecal urgency, dyspareunia and psychological effects for women. A meta-analysis found that 30%-50% of women were symptomatic one year after OASIS, even with repaired[1, 2]. And it could result in as high as 53%-80% of longer-term anal incontinence and urgency[3, 4], affecting women’s quality of life. The purpose of episiotomy is to expedite delivery for fetal distress, increase the vaginal outlet of instrumental deliveries or shoulder dystocia, or to reduce the risk of OASIS[5]. Episiotomy as the most important preventative measure to reduce third-and fourth-degree or OASIS is used worldwide, despite the confliction of the protective effect[6, 7]. Episiotomy technique usually contains three main parameters: the length of the incision, the incision angle, and the distance between the start point and the posterior fourchette. Several episiotomies were described, the midline episiotomy is associated with high rates of OASIS[8–10], compared with mediolateral episiotomy (MLE), there was no significant difference in pain, dyspareunia and infection rates[11].
The WHO recommends restrictive use of episiotomy, and states that episiotomy should be considered as following: complicated vaginal delivery (breech, shoulder dystocia, forceps or vacuum extraction), scarring from female genital mutilation or poor healed third-or fourth-tears, fetal distress. Restrictive episiotomy resulted in less OASIS and fewer healing complications compared to routine episiotomy[12]. The use of episiotomy is restrictive, rather than routine, and left MLE is considered standard practice in China.
The internationally accepted standardized definition or categorization of episiotomy is still on the way, the National institute of Health and Care Excellence (NICE 2007) guideline for intrapartum care recommended that a MLE should perform originating at the vaginal fourchette and the angle to the vertical axis should be between 45 and 60 degrees. Dharmesh et al. found that perineal distension of 170% in the transverse direction and 40% in the vertical direction at crowning, there are 15–30 degree between episiotomy incision angles and suture angles, suture angles of 40–60 degrees are in the safe zone[9].Performing a MLE at least 60 degree from midline may in fact protect against OASIS[13], and there is a U-shaped association between suture angles and risk of OASIS, 30–60 degrees are the safe zone[14]. When suture angle was 25 degrees, there was a 10% incidence of OASIS and each additional 6 degrees away from midline reduced half of this risk, the incidence was only 0.5% at the suture angle of 45 degrees[15–17]. The revised Royal College of Obstetricians and Gynecologists (RCOG) (Green-top guideline 2015 NO.29) recommends three preventative measures to reduce the risk of OASIS as flowing: episiotomies at 60 degrees to the midline at crowning, manual perineal protection and warm perineal compresses in second stage of labor.
MLE must be performed correctly for better preventing anal sphincter injury. Stedenfeldt et al. concluded that episiotomies with depth > 16 mm, length > 17 mm, incision point > 9 mm lateral of midpoint and suture angle range 30–60 degrees are significantly associated with less risk of OASIS[14]. Trainings became the main method of improving skills for junior doctors and midwifes. The knowledge of performing a proper MLE and repair had universally introduced and trained.
Doctors tend to cutting longer episiotomy and more obtuse angle compared with midwives[18, 19]. Personal career may affect the effect of such training. The impact of training between senior and junior practitioners is rare seen in previous researches. The aim of this study was to evaluate the training effect among variant practitioners, accompany with their knowledge and accuracy of episiotomy before and after the training.