Re: Maternal and neonatal trauma during forceps and vacuum delivery must not be overlooked
We appreciate Dr. Datta’s response (1) to our article (2) and are pleased to address the issues raised.
The association between race/ethnicity and obstetric anal sphincter injury (OASI) is indeed an important issue as several studies have reported 1.5- to 3.0-fold higher rates of OASI in Asian vs White individuals living in high-income countries such as Australia, (3) Canada, (4) Norway, (5) the United Kingdom, (6) and the United States. (7) These higher rates persist even after adjustment for operative vaginal delivery and episiotomy. In contrast, rates of OASI among Asian individuals residing in Asia do not parallel these high rates. (8,9) The increased risk of OASI among Asian vs. White individuals should be considered when communicating the risks and benefits associated with the different options for second-stage operative delivery. In the Canadian context, a 1.5-fold increase in the rate of OASI among spontaneous vaginal, forceps, and vacuum deliveries would result in an OASI rate of 4.2%, 32.3%, and 17.6%, respectively, among Asian patients, and these rates would be even higher among those birthing for the first time. In an effort to better quantify and understand racial differences in OASI, we are conducting a systematic review and meta-analysis to synthesize published studies on the association between Asian race and OASI. (10) In this review, we are also addressing potential heterogeneity in these associations among different Asian subgroups (e.g., Chinese, Indian, and Japanese), and exploring proposed causal mechanisms for the increased risk of OASI among Asian vs White individuals (e.g., perineal body length, maternal pre-pregnancy body mass index, fetal-maternal size disproportion, infant head circumference, and language barriers).
Regarding the role of indication for operative vaginal delivery and pelvic station - in a previous study using Canadian population-based data, we quantified OASI rates after stratifying by instrument (forceps and vacuum) indication (dystocia and fetal distress), and pelvic station (outlet, low, and mid-pelvic). (11) Rates of OASI were modified by pelvic station but remained high among all operative vaginal deliveries, regardless of indication. We have not as yet assessed the role of duration of labour (first and second stage) or labour augmentation on the rates of OASI in Canada. Assessing the patient's understanding of how to push during the second stage of labour is another factor that warrants further study.
Interventions such as mediolateral episiotomy (performed at a 60° angle from the midline at crowning of the fetal head), (12) warm compress, perineal massage, and perineal support are all features of perineal care bundles. Choosing the interventions to include in a care bundle will require consultation with patients and clinicians regarding what is acceptable to patients and feasible within the existing labour and delivery services framework.
1. Datta S. Re: Maternal and neonatal trauma during forceps and vacuum delivery must not be overlooked. https://www.bmj.com/content/383/bmj-2022-073991/rapid-responses
2. Muraca G M, Ralph L E, Christensen P, D’Souza R, Geoffrion R, Lisonkova S et al. Maternal and neonatal trauma during forceps and vacuum delivery must not be overlooked. BMJ 2023;383:e073991.
3. Baghurst PA, Antoniou G. Risk models for benchmarking severe perineal tears during vaginal childbirth: a cross-sectional study of public hospitals in south Australia, 2002–08. Paediatr Perinat Epidemiol 2012;26(5):430-437.
4. Albar M, Aviram A, Anabusi S, Huang T, Tunde-Byass M, Mei-Dan E. Maternal ethnicity and the risk of obstetrical anal sphincter injury: a retrospective cohort study. J Obstet Gynaecol Can 2021;43(4):469-473.
5. Sørbye IK, Bains S, Vangen S, Sundby J, Lindskog B, Owe KM. Obstetric anal sphincter injury by maternal origin and length of residence: a nationwide cohort study. BJOG 2022;129(3):423-431.
6. Gurol-Urganci I, Cromwell DA, Edozien LC, et al. Third- and fourth-degree perineal tears among primiparous women in England between 2000 and 2012: time trends and risk factors. BJOG 2013;120(12):1516-1525.
7. Handa VL, Danielsen BH, Gilbert WM. Obstetric anal sphincter lacerations. Obstet Gynecol 2001;98(2):225-230.
8. Wheeler J, Davis D, Fry M, Brodie P, Homer CSE. Is Asian ethnicity an independent risk factor for severe perineal trauma in childbirth? A systematic review of the literature. Women Birth J Aust Coll Midwives 2012;25(3):107-113.
9. Bates LJ, Melon J, Turner R, Chan SSC, Karantanis E. Prospective comparison of obstetric anal sphincter injury incidence between an Asian and Western hospital. Int Urogynecology J 2019;30(3):429-437.
10. Park M, Wanigaratne S, D'Souza R, Geoffrion R, Williams SA, Muraca GM. Asian-white disparities in obstetric anal sphincter injury: Protocol for a systematic review and meta-analysis. PLoS One 2023 Sep 8;18(9):e0291174.
11. Muraca GM, Sabr Y, Lisonkova S, Skoll A, Brant R, Cundiff GW, Joseph KS. Morbidity and mortality associated with forceps and vacuum delivery at outlet, low, and midpelvic station. J Obstet Gynaecol Can 2019;41(3):327-337.
12. Okeahialam NA, Wong KW, Thakar R, Sultan AH. The incidence of wound complications following primary repair of obstetric anal sphincter injury: a systematic review and meta-analysis. Am J Obstet Gynecol 2022;227(2):182-191.
Competing interests: No competing interests