Obstetric anal sphincter injuries occur in 2.9% of vaginal deliveries in the UK (Thiagamoorthy et al, 2014), and 38% of pregnant people experience anal incontinence following primary repair of an obstetric anal sphincter injury (Sideris et al, 2020). A mediolateral episiotomy is known to reduce the risk of obstetric anal sphincter injuries during assisted vaginal deliveries (van Bavel et al, 2018). In nulliparous pregnant people, mediolateral episiotomies are associated with an eightfold reduction in the rate of obstetric anal sphincter injuries during forceps birth and a sixfold reduction during vacuum extraction (van Bavel et al, 2018).
Some 64% of midwives and obstetricians have reported dissatisfaction with their training prior to performing their first perineal repair (Andrews et al, 2005). In the UK, it is now mandatory for trainees in obstetrics and gynaecology to attend a practical training course in perineal trauma. In addition, the Royal College of Obstetricians and Gynaecologists have introduced an objective structured assessment of technical skills. Trainees in obstetrics and gynaecology have to demonstrate competence in this technical skill prior to completing their specialist training (Royal College of Obstetricians and Gynaecologists, 2021). Similarly, preceptee midwives must witness and undergo supervision when performing perineal repairs.
The angle at which a mediolateral episiotomy is performed is critical to minimising the risk of obstetric anal sphincter injuries. An angle of 60° from the midline is recommended, as it is known to be associated with the lowest risk of an obstetric anal sphincter injuries (Sultan et al, 2019).
With the introduction of training and assessment for perineal repair, the authors aimed to determine if midwives and doctors were aware of the optimal angle for a mediolateral episiotomy incision.
Methods
A convenience sample of doctors and midwives were invited by one of the researchers (KW) to complete an interview-administered questionnaire, with the aim of understanding their reasons for performing a mediolateral episiotomy and determining their perceived optimal angle. All available doctors and midwives from the labour ward of one hospital were invited to participate. Convenience sampling was used as it was the most efficient method to recruit participants to a questionnaire. This has the potential limitation of under-representing a particular subgroup, but the study results did not demonstrate this.
Data collection
The questionnaire used for data collection was a previously established research tool. It was interviewer administered and was completed by participants in under 20 minutes. The questionnaire asked participants:
- Their role, rank and years of experience
- Whether they had any formal training in episiotomy
- How many episiotomies they had done while supervised (possible answers: 0–5, 6–10, >10)
- How many episiotomies they had done while unsupervised (possible answers: 0–5, 6–10, >10)
- How long (in cm) they would make the cut for an episiotomy
- What angle they would make the cut
- Why they would perform an episiotomy
- What they worried about when performing an episiotomy
- What muscles or structures are cut during an episiotomy.
In addition, a pictorial representation of the perineum (Wong et al, 2014) was given to participants, so that they could depict the way in which they would perform a mediolateral episiotomy (Figure 1). This study was conducted between January–December 2018 in a London maternity unit.
Data analysis
Data were entered into Microsoft Excel and analysed using the statistical package for social sciences (version 28). The normality of distribution was assessed using the Kolmogorov-Smirnov test. The Mann-Whitney U test was used to compare differences in medians between two groups and the Kruskal-Wallis test was used to compare differences in medians across three or more groups. P<0.05 was considered statistically significant.
Ethical considerations
Ethical approval was not required for this study, as it was part of the internal organisation needs assessment and therefore exempt from institutional review board review as a service evaluation. Participants gave verbal consent to participate in the study and all data were anonymised.
Results
A total of 78 clinicians (53 midwives and 25 doctors) participated in the study. Of the 53 midwives, six were student midwives (between their first and third year of training), 35 were junior midwives (band 5 and 6) and 12 were senior midwives (bands 7 and 8). Of the 25 doctors, 17 were trainees and eight were consultants or had completed specialist training.
A total of 24 clinicians (31%), who were all junior midwives and trainee doctors, had not received any formal training in how to perform a mediolateral episiotomy. Overall, 14 doctors (56%) and five (9%) midwives had performed over 10 supervised mediolateral episiotomies; however, 24 (45%) midwives had never performed a mediolateral episiotomy with supervision, in comparison to four doctors (16%).
Midwives described performing mediolateral episiotomies that were significantly closer to the midline than those by obstetricians (median 45° compared with 60°, P<0.05). Similarly, midwives depicted more acute mediolateral episiotomies when compared to obstetricians (median 50° compared with 62°, P<0.05). Both midwives and doctors drew mediolateral episiotomies of a similar length (3.50cm; interquartile range for doctors was 3.00–4.00cm, interquartile range for midwives was 2.75–4.25cm, P=0.271). Nine clinicians commented that the length that they would perform an mediolateral episiotomy depended on the clinical situation or characteristics of the perineum. Doctors and midwives that had performed more than 10 supervised mediolateral episiotomies were more likely to describe and draw them at an angle of 60° (Table 1).
Table 1. Supervised mediolateral episiotomies and described and depicted mediolateral episiotomies (Kruskal-Wallis test)
| Supervised mediolateral episiotomies | 0–5 | 6–10 | >10 | P value |
|---|---|---|---|---|
| Median described angle (interquartile range) (o) | 45.00 (37.50–52.50) | 56.25 (48.75–63.75) | 60.00 (52.50–67.50) | 0.040 |
| Median drawn angle (interquartile range) (o) | 50.00 (41.50–58.50) | 55.00 (47.50–62.50) | 60.00 (50.00–70.00) | 0.031 |
| Median length (interquartile range) (cm) | 4.00 (3.25–4.75) | 3.00 (2.25–3.75) | 3.50 (3.20–3.80) | 0.300 |
Years of experience as a midwife or doctor, their grade, the number of unsupervised mediolateral episiotomies they had performed and their completion of formal training had no significant impact on the angle of an mediolateral episiotomy that a clinician described or depicted (Tables 2–5).
Table 2. Years of experience and described and depicted mediolateral episiotomies (Kruskal-Wallis test)
| Years of experience | 0–5 | 6–10 | >10 | P value |
|---|---|---|---|---|
| Median described angle (interquartile range) (o) | 52.50 (45.00–60.00) | 52.5 (45.00–60.00) | 52.5 (44.50–60.50) | 0.783 |
| Median drawn angle (interquartile range) (o) | 50.00 (40.50–59.50) | 57.0 (46.00–66.00) | 53.0 (47.00–59.00) | 0.398 |
| Median length (interquartile range) (cm) | 3.50 (2.75–4.35) | 3.50 (3.10–3.90) | 3.50 (2.75–4.35) | 0.503 |
Table 3. Grade of clinician and described and depicted mediolateral episiotomies (Mann-Whitney U test)
| Grade of clinician | Junior doctors and band 5 and 6 midwives | Consultants and band 7 and 8 midwives | P value |
|---|---|---|---|
| Median described angle (interquartile range) (o) | 45.00 (37.50–52.50) | 52.50 (45.00–60.00) | 0.349 |
| Median drawn angle (interquartile range) (o) | 52.00 (46.00–58.00) | 54.00 (43.00–65.00) | 0.860 |
| Median length in cm (interquartile range) | 3.50 (3.00–4.00) | 3.75 (2.95–4.55) | 0.415 |
Table 4. Unsupervised mediolateral episiotomies and described and depicted mediolateral episiotomies (Mann-Whitney U test)
| Unsupervised mediolateral episiotomies | 0–10 | >10 | P value |
|---|---|---|---|
| Median described angle (interquartile range) (o) | 45.00 (37.50–52.50) | 60.00 (52.50–67.50) | 0.047 |
| Median drawn angle (interquartile range) (o) | 50.00 (40.50–59.50) | 58.00 (50.50–65.50) | 0.215 |
| Median length (interquartile range) (cm) | 3.50 (2.75–4.25) | 3.50 (2.95–4.05) | 0.134 |
Table 5. Attendance at formal training sessions and described and depicted mediolateral episiotomies (Mann-Whitney U test)
| Attended formal training sessions | Yes | No | P value |
|---|---|---|---|
| Median described angle (interquartile range) (o) | 56.25 (48.75–63.75) | 45.00 (37.50–52.50) | 0.156 |
| Median drawn angle (interquartile range) (o) | 51.50 (44.00–59.00) | 52.00 (44.00–60.00) | 0.776 |
| Median length (interquartile range) (cm) | 3.50 (2.80–4.20) | 3.00 (2.50–3.50) | 0.304 |
The most common indications for performance of a mediolateral episiotomy, as described by clinicians, were suspected fetal compromise (41%) and instrumental birth (36%), and to expedite birth (35%). The most common concerns described related to mediolateral episiotomies were bleeding (29%), anal sphincter injury (22%) and extension of the mediolateral episiotomy (18%). A total of 14 clinicians (18%) were worried that they may be performing a mediolateral episiotomy at the wrong angle, and 12 (15%) were also concerned that they may accidentally cut the baby or the umbilical cord. Two were worried about cutting themselves, and another two felt that performing a mediolateral episiotomy was technically challenging. Five of the 25 doctors (20%) and none of the midwives were able to correctly identify the muscles that are cut when performing a mediolateral episiotomy (the bulbospongiosus and the superficial transverse perineal muscles). Clinicians who demonstrated awareness of the structures that are cut during an mediolateral episiotomy were significantly more likely to depict a more obtuse angle of incision (median 70° compared with 52°, P=0.02) (Table 6).
Table 6. Knowledge of anatomical structures cut when performing mediolateral episiotomy and described and depicted mediolateral episiotomies (Mann-Whitney U test)
| Correct understanding of structures cut | Yes | No | P value |
|---|---|---|---|
| Median described angle (interquartile range) (o) | 60.00 (52.50–60.00) | 45.00 (45.00–60.00) | 0.198 |
| Median drawn angle (interquartile range) (o) | 70.00 (55.00–71.50) | 52.00 (45.00–60.00) | 0.020 |
| Median length (interquartile range) (cm) | 4.50 (3.30–6.10) | 3.50 (3.00–4.00) | 0.134 |
Discussion
This study involved 78 clinicians (53 midwives and 25 doctors) Doctors described performing a mediolateral episiotomy at 60° from the midline, in keeping with recommended practice (Royal College of Obstetricians and Gynaecologists, 2015). However, midwives reported that mediolateral episiotomies should be performed at 45° from the midline. Midwives and doctors that had been supervised for 10 or more mediolateral episiotomies were aware of the recommended angle for episiotomy and depicted a mediolateral episiotomy at 60° from the midline. Clinicians who were aware of the structures that are cut when performing a mediolateral episiotomy were significantly more likely to depict a more obtuse angle.
The angle of a mediolateral episiotomy is critical, and it is known that, for every 6o further from the midline that an episiotomy is performed, there is a 50% reduction in the risk of an obstetric anal sphincter injuries (Eogan et al, 2006). Perineal distention occurs as the fetal head crowns, and the cut angle of the mediolateral episiotomy becomes more acute following delivery and repair (Kalis et al, 2008; 2011). It is known that an angle of 60° from the midline is associated with the lowest incidence of obstetric anal sphincter injuries (Sultan et al, 2019). Wong et al (2014) interviewed 100 doctors and midwives in the UK who reported that a mediolateral episiotomy should be performed at 45° from the midline. This more recent study suggests that obstetricians are increasingly aware that a mediolateral episiotomy needs to be performed at an angle of 60° as opposed to 45°; however, midwives still reported that they understood correct angle for a mediolateral episiotomy was at 45° from the midline. In the UK, objective structured assessments of technical skills for perineal repair have been introduced as a requirement for trainee doctors, which may explain the observed improvement in their understanding of the correct angle at which to perform a mediolateral episiotomy (Royal College of Obstetricians and Gynaecologists, 2022). Objective structured assessments of technical skills facilitate supervision, feedback and reflection; therefore, adoption of a similar assessment for midwives should be given consideration.
Doctors and midwives that had been directly supervised during at least 10 mediolateral episiotomies were able to describe and depict a mediolateral episiotomy at 60° from the midline. Those that had not been supervised for 10 procedures drew and depicted mediolateral episiotomies that were closer to the midline. This is in keeping with the findings of Wong et al (2014), who found that doctors and midwives who had not been supervised for at least 10 mediolateral episiotomies described more acute mediolateral episiotomies and drew ones that were positioned more closely to the midline.
Training in all surgical specialties has evolved over the last 20 years, and there has been widespread introduction of work-based assessments for competency. However, there is a paucity of evidence to support such assessments in surgical specialties (Torsney et al, 2015). Therefore, consideration should be given to combining work-based assessments with undertaking at least 10 supervised mediolateral episiotomies prior to being deemed competent.
Approximately a fifth of doctors in the present study were aware of the structures that are cut when performing a mediolateral episiotomy. This group of doctors was also significantly more likely to depict a mediolateral episiotomy angle at a greater distance from the midline. These findings are consistent with those of Wong et al (2014), who found that 18% of doctors and no midwives were able to identify the perineal muscles involved when cutting a mediolateral episiotomy. To the best of the authors’ knowledge, this is the first paper to suggest that a detailed knowledge of the perineal muscles may contribute to the angle at which a mediolateral episiotomy is performed in practice.
The strengths of the current study included the use of an interview-based questionnaire that has been used previously, and blinding of the investigator to the angle initially stated by the participant. A weakness of the present study is that depicting a mediolateral episiotomy on a pictorial representation of a perineum may not accurately reflect a clinician's real-world practice.
Key points
- When a mediolateral episiotomy is performed at an angle of 60° from the midline, it is associated with the lowest incidence of obstetric anal sphincter injury.
- Doctors were aware of current guidelines and depicted episiotomies that were 60° from the midline; however, midwives reported that this procedure should be performed at a 45° angle.
- Both doctors and midwives that had performed at least 10 episiotomies under supervision knew that a mediolateral episiotomy should be performed at 60° from the midline.
- It is suggested that all practitioners performing episiotomies should be supervised for a minimum of 10 procedures before progressing onto independent practice.
CPD reflective questions
- Do you feel you performed enough episiotomies under supervision prior to independent practice?
- How can better clinical supervision for performance of episiotomies be facilitated?
Conclusions
When a mediolateral episiotomy is performed, it should be at 60° from the midline, as this is the angle least likely to result in an obstetric anal sphincter injury. Doctors were aware of this, and depicted episiotomies that were 60° from the midline; however, midwives reported they should be performed at 45°. Both doctors and midwives that had performed at least 10 episiotomies under supervision knew that a mediolateral episiotomy should be performed at 60° from the midline. Objective structured assessments of technical skills for perineal trauma are mandatory for obstetrics trainees in the UK. The authors suggest that consideration should be given to introducing these assessments for perineal trauma for midwives and that all practitioners performing episiotomies should be supervised for a minimum of 10 procedures before being deemed competent.