OBJECTIVE: This study aimed to evaluate if induction of labor (IOL) is associated with an increased risk of severe perineal laceration.
METHODS: A systematic search was conducted in MEDLINE, Ovid, Scopus, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials, and CINHAL using a combination of keywords and text words related to \"induction of labor,\" \"severe perineal laceration,\" \"third-degree laceration,\" \"fourth-degree laceration,\" and \"OASIS\" from inception of each database until January 2023.
METHODS: We included all randomized controlled trials (RCTs) comparing IOL to expectant management of a singleton, cephalic pregnancy at term gestation that reported rates of severe perineal laceration.
UNASSIGNED: The primary outcome of interest was severe perineal laceration, defined as 3rd- or 4th-degree perineal lacerations. We conducted meta-analyses using the random effects model of DerSimonian and Laird to determine the relative risks (RR) or mean differences with 95% confidence intervals (CIs). Bias was assessed using guidelines established by Cochrane Handbook for Systematic Reviews of Interventions.
RESULTS: A total of 11,187 unique records were screened and ultimately eight RCTs were included, involving 13,297 patients. There was no statistically significant difference in the incidence of severe perineal lacerations between the IOL and expectant management groups (209/6655 [3.1%] vs 202/6641 [3.0%]; RR 1.03, 95% CI 0.85, 1.26). There was a statistically significant decrease in the rate of cesarean birth (1090/6655 [16.4%] vs 1230/6641 [18.5%], RR 0.89, 95% CI 0.82, 0.95) and fetal macrosomia (734/2696 [27.2%] vs 964/2703 [35.7%]; RR 0.67: 95% CI 0.50, 0.90) in the IOL group.
CONCLUSIONS: There is no significant difference in the risk of severe perineal lacerations between IOL and expectant management in this meta-analysis of RCTs. Furthermore, there is a lower rate of cesarean births in the IOL group, indicating more successful vaginal deliveries with similar rates of severe perineal lacerations. Patients should be counseled that in addition to the known benefits of induction, there is no increased risk of severe perineal lacerations.

Perineal wound infection can affect tissues at superficial, deep, and organ space levels. Women with obstetric anal sphincter injuries (OASIS) are at risk of infection; however, no study to date has investigated if infection can extend to affect the anal sphincter integrity. The aim of this study was to evaluate the clinical progression of perineal wound infection and its effect on the anal sphincter in women with or without OASIS using three-dimensional endoanal ultrasound (3D-EAUS).
Women were recruited into the Prospective Observational Study Evaluating the Sonographic Appearance of the Anal Sphincter in Women With Perineal Wound Infection Following Vaginal Delivery (PERINEAL Study) between August 2020 and August 2021 (NCT04480684). 3D-EAUS was performed weekly until complete wound healing. Significant bacterial colonization was diagnosed using the MolecuLight i:X camera. The primary study outcome was a change in a sphincter defect angle from baseline (wound infection) until wound healing. A robust Poisson regression model was used to analyze the effect of significant bacterial loads on the anal sphincter.
Seventy-three women were included. A median of two ultrasound scans were performed in each patient (range 1-16). Five women (6.8%) had an OASI clinically diagnosed at delivery. In total, 250 EAUS were performed. An external anal sphincter defect was found on EAUS in 55 (22.0%) scans (n = 10 women). An external anal sphincter and internal anal sphincter defect was found in 26 scans (10.4%) (n = 3 women). During the course of the wound healing process, there was no significant change in defect size in wounds with or without significant bacterial colonization. In cases of an intact anal sphincter, wound infection did not disrupt its integrity.
We found that perineal wound infection does not disrupt an intact anal sphincter or OASIS. This new information can provide important information for clinicians and patients. As there are myths frequently encountered in cases of litigation when disruption of sphincter integrity is attributed to perineal infection, the findings of this study should be tested in larger studies in the future.

To develop and validate a model to predict obstetric anal sphincter injuries (OASIS) using only information available at the time of admission for labour.
A clinical predictive model using a retrospective cohort.
A US health system containing one community and one tertiary hospital.
A total of 22 873 pregnancy episodes with in-hospital delivery at or beyond 21 weeks of gestation.
Thirty antepartum risk factors were identified as candidate variables, and a prediction model was built using logistic regression predicting OASIS versus no OASIS. Models were fit using the overall study population and separately using hospital-specific cohorts. Bootstrapping was used for internal validation and external cross-validation was performed between the two hospital cohorts.
Model performance was estimated using the bias-corrected concordance index (c-index), calibration plots and decision curves.
Fifteen risk factors were retained in the final model. Decreasing parity, previous caesarean birth and cardiovascular disease increased risk of OASIS, whereas tobacco use and black race decreased risk. The final model from the total study population had good discrimination (c-index 0.77, 95% confidence interval [CI] 0.75-0.78) and was able to accurately predict risks between 0 and 35%, where average risk for OASIS was 3%. The site-specific model fit using patients only from the tertiary hospital had c-stat 0.74 (95% CI 0.72-0.77) on community hospital patients, and the community hospital model was 0.77 (95%CI 0.76-0.80) on the tertiary hospital patients.
OASIS can be accurately predicted based on variables known at the time of admission for labour. These predictions could be useful for selectively implementing OASIS prevention strategies.

OBJECTIVE: Our objectives were to study the association between epidural analgesia and risk of severe perineal laceration (SPL), and identify additional risk factors for SPL. This multicentre study consisted of an analysis of data from the MidconBirth Phase I Database, on the use of EA and perineal results during childbirth. (World Health Organization, International Clinical Trials Registry Platform, 2016: http://apps.who.int/trialsearch/Trial2.aspx?TrialID=ISRCTN17833269).
METHODS: We conducted a prospective study of pregnant women at term between July 2016 and July 2017 in 30 public maternity hospitals in Catalonia, Spain. Inclusion criteria were an uncomplicated singleton pregnancy, in cephalic presentation and vaginal birth. Data was analysed separately for instrumental births and spontaneous vaginal births, as the former is more frequently associated with episiotomy and more perineal lacerations. Risk factors as well as protective factors in each cohort of women (instrumental and spontaneous vaginal birth), were identified. Multivariate logistic regression model was performed to study the association between epidural analgesia and SPL to identify potential confounders. Odds ratios (OR), using 95% confidence intervals (CI) were constructed.
RESULTS: During the study period, 5497 eligible women gave birth, 77.46% of them received epidural analgesia. SPL occurred in 1.63% of births. The univariate analysis showed births with epidural analgesia had significantly higher rates of inductions, augmentation of labour, lithotomy position for birth and episiotomy. However, this association disappeared when the variable \"type of vaginal birth\" was introduced. In multivariate logistic regression, nulliparity was the major predictor for SPL (OR: 0.17; CI 95%: 0.08-0.34, p: 0.000).
CONCLUSIONS: Epidural analgesia was not associated with SPL once confounding factors were included. Other interesting factors associated with SPL were identified.
CONCLUSIONS: This paper identifies important practice areas which contribute to SPL and which have the potential to be rectified. It offers evidence on the role that EA plays on pelvic floor injuries and it adds to existing evidence about the disadvantages of using the lithotomy position for birth, especially in relation to SPL. It highlights the need for practice change in Catalonia from what can be considered a medical model of care to one more aligned with the midwifery philosophy of care through the development of clinical guidelines. It also signals the need to provide women with evidence base upon which to make informed choices on the use of EA, specifically in relation to SPL.

OBJECTIVE: To evaluate whether Asian race is an independent risk factor for severe perineal lacerations.
METHODS: We performed a nationwide population-based retrospective cohort study examining the relationship between Asian race and severe perineal lacerations (third and fourth degree). The data were collected from the 2012 Healthcare Cost and Utilization Project National Inpatient Sample (HCUP-NIS). Characteristics of Asian American women were compared with those of non-Asian women. The primary outcome of interest was severe perineal lacerations. Multivariable logistic regression was used to refine the associations between Asian race and severe perineal lacerations while adjusting for confounding effects. Results were compared with previously published data using a pooled odds ratio.
RESULTS: 2,270,044 Women with singleton vaginal deliveries were identified, and 120,452 (5.3%) were Asian. After adjusting for confounders, Asian women were more likely to experience severe perineal lacerations than any other racial group (3.5% versus 6.3%, adjusted odds ratio [aOR] 1.50, 99% CI 1.29-1.74, p < 0.0001). Analysis of literature indicated that Asian American women are 74% more likely to experience severe perineal lacerations (aOR 1.74, 99% CI 1.72-1.76, p < 0.0001) than non-Asians.
CONCLUSIONS: Asian race is an independent risk factor for severe perineal lacerations in the United States.