Study finds lateral episiotomy reduces risk of obstetric anal sphincter injury | Image credit: © Summit Art Creations – © Summit Art Creations – stock.adobe.com.
Lateral episiotomy is a safe and effective procedure for reducing the risk of obstetric anal sphincter injury in non-childbearing women, according to a recent study published in . BMJ.
Takeaway
- A study recently published BMJ found that lateral episiotomy significantly reduces the risk of obstetric anal sphincter injuries in childless women undergoing vacuum extraction.
- The incidence of anal sphincter injury was 6% in women who underwent a lateral episiotomy compared with 14% in those who did not, and the adjusted risk ratio was 0.47.
- The study included 702 nonparturient women from 8 hospitals in Sweden who were randomized to receive or not receive a lateral episiotomy during vacuum extraction.
- While second-degree injuries, wound infections, and dehiscence were more common in the intervention group, there were no significant differences in total self-referred or serious adverse events between the groups.
- Based on the findings, lateral episiotomy is recommended for prenatal women requiring vacuum extraction, with further research on patient-reported long-term outcomes needed.
During vaginal birth, obstetric anal sphincter injury leads to anal incontinence and adversely affects quality of life. The rate of obstetric anal sphincter injury ranges from 0.1% to 4% for spontaneous births and 6% to 24% for instrumental births.
The efficacy of episiotomy for preventing obstetric anal sphincter injury is still unclear, with some studies indicating a possible increased risk. Other studies have reported no effect or the opposite effect. This has caused episiotomy use to vary considerably across births by device, ranging from 17.1% in Denmark to 97.2% in Poland.
To evaluate the effect of episiotomy on the risk of anal sphincter injury in a sample of sufficient size, the investigators conducted a randomized controlled trial. From July 1, 2017 to February 15, 2023, 8 hospitals in Sweden participated in the analysis.
Participants included nulliparous women undergoing vacuum excision for a single, live, cephalic fetus from 34 weeks' gestation onwards. Women who had previously undergone surgery for urinary or anal incontinence or genital prolapse were excluded from the study.
The attending physicians decided to perform vacuum excision independently of study participation. Next, a 1:1 randomization was performed to determine whether patients would receive an episiotomy.
All vacuum extraction procedures were performed on a clinical routine basis. The attending physician performed the extraction until the fetal head was at the top. At this point, the physician or midwife completed the lateral episiotomy, which included examining the injury, suturing the injury, and standard procedures used for postpartum care.
Perineal pain was assessed daily sometime between days 1 and 7 after birth. Complications were identified through a questionnaire sent 2 months after the baby's birth.
The primary outcome of the analysis was obstetric anal sphincter injury, determined by a third- or fourth-degree perineal injury of the external or internal anal sphincter muscles requiring surgical repair. This diagnosis was made by the attending physician based on Swedish guidelines.
Additional maternal outcomes included other vaginal or perineal injury, length of hospital stay, perineal pain, and birth experience. Neonatal outcomes included 5-minute Apgar score less than 7, metabolic acidosis, admission to the neonatal intensive care unit, fetal fracture, scalp hematoma, shoulder dystocia, obstetric brachial plexus palsy, hypoxic ischemic encephalopathy, and neonatal seizures.
Postpartum hemorrhage and severe perineal pain were reported as safety outcomes. The Swedish Pregnancy Register was evaluated for demographics, maternal and delivery characteristics, and outcomes.
Serious adverse events were those that resulted in maternal death within 42 days of delivery or death of the newborn within 28 days of birth. All adverse events were determined on the basis of self-referral.
The analysis included 344 women who were allocated to a lateral episiotomy and 358 who were not allocated to an episiotomy. 6% of women allocated to a lateral episiotomy reported a caesarean delivery after failed vacuum extraction, while 1% of women allocated to no episiotomy reported a caesarean delivery after failed vacuum extraction.
A risk difference of -7% was reported for obstetric anal sphincter injury between groups, 6% allocated to lateral episiotomy vs 14% allocated to no episiotomy. The adjusted risk ratio was 0.47, reporting largely consistent findings across study sites and sensitivity analyses.
In the per protocol population, the risk difference for obstetric anal sphincter injury was -6.5%, 6% for women receiving a lateral episiotomy and 13% for women not receiving an episiotomy. Results for the total intention-to-treat population were consistent for modified intention-to-treat and per protocol analyses.
Only a few cases of intact perineum were reported, and the intervention group had fewer first-degree injuries and more second-degree injuries than the comparison group. Wound infection and dehiscence were also significantly more common in the intervention group. However, differences were not observed for total self-referred adverse events or serious adverse events.
These results indicate that lateral episiotomy may be recommended in nulliparous women requiring vacuum extraction. The investigators recommended that more evidence should be obtained regarding long-term patient reported outcomes.
Reference
Bergendahl S, Jonsson M, Hesselman S, et al. Lateral episiotomy or no episiotomy in vacuum assisted delivery in nulliparous women (EVA): a multicentre, open label, randomised controlled trial. BMJ. 2024;385:e079014. doi:10.1136/bmj-2023-079014