Risk Factors for the Development of Obstetric Anal Sphincter Injuries in Modern Obstetric Practice

Background. Obstetric anal sphincter injuries (OASIS) arise from perineal trauma during vaginal delivery and are associated with poor maternal health outcomes. Most OASIS occur in unattended deliveries in resource-limited settings. However, even in facilities where deliveries are attended by skilled personnel, a number of women still get OASIS. Objectives. To determine the incidence and risk factors for obstetric anal sphincter injuries among women delivering at Mbarara Regional Referral Hospital (MRRH). Methods. We conducted an unmatched hospital-based case control study, with the ratio of cases to controls of 1 : 2 (80 cases and 160 controls). We defined a case as a mother who got a third- or fourth-degree perineal tear after vaginal delivery while the controls recruited were the next two mothers who delivered vaginally without a third- or fourth-degree perineal tear. A questionnaire and participants’ medical records review were used to obtain sociodemographic and clinical data. We estimated the incidence of OASIS and performed univariable and multivariable logistic regression to identify the associated risk factors. Results. The cumulative incidence for OASIS during the study period was 6.6%. The risk factors for OASIS were 2nd stage of labour ≥1 hour (aOR 6.07, 95%CI 1.86–19.82, p=0.003), having episiotomy performed during labour (aOR 2.57, 95%CI 1.07–6.17, p=0.035), perineum support during delivery (aOR 0.03, 95%CI 0.01–0.12, p<0.001), and monthly income of >50,000 shillings (aOR 0.09, 95%CI 0.03–0.28, p<0.001). Conclusions and Recommendations. The risk factors for obstetric anal sphincter injury were prolonged second stage of labour and performing episiotomies during deliveries while higher monthly income and perineum support during delivery were protective. We recommend routine support to the perineum during delivery. Care should be taken in mothers with episiotomies, as they can extend and cause OASIS.

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Obstetric Anal Sphincter Injuries – Maternal, Foetal and Sociodemographic Risk Factors: A Retrospective Register-Based Study

10.22541/au.163460613.32885708/v1 ◽

2021 ◽

Author(s):

Kristin André ◽

Andrea Stuart ◽

Kärin Kallén

Keyword(s):

Risk Factors ◽

Birth Weight ◽

Caesarean Section ◽

Anal Sphincter ◽

Maternal Education ◽

Vacuum Extraction ◽

High Birth Weight ◽

Previous Caesarean Section ◽

Obstetric Anal Sphincter Injuries ◽

Increased Risk

Objective. To determine risk and protective factors of obstetric anal sphincter injuries (OASIS). Design. A retrospective register-based observational study. Setting. Sweden. Population. A cohort of 988, 988 singleton term deliveries 2005-2016 were included. Methods. Data from the Swedish Medical Birth Registry and Statistics Sweden were extracted to identify cases of OASIS and maternal and foetal characteristics. Modified Poisson Regression analyses were performed to assess risk factors. Main outcome measures. Risk ratios for OASIS with 95% confidence interval associated with maternal and foetal risk factors were calculated. Results. The rate of OASIS was 3.5% (n=34, 583). Primiparity (aRR 3.13 95% CI 3.05–3.21), vacuum extraction (aRR 2.79 95% CI 2.73–2.86), forceps (aRR 4.27 95% CI 3.86–4.72) and high birth weight (aRR 2.61 95% CI 2.50–2.72) were associated with a significantly increased risk of OASIS. Increasing maternal age and decreasing maternal height increased the risk of OASIS. Smoking (aRR 0.74 95% CI 0.70–0.79) and low maternal education (aRR 0.87 95% CI 0.83–0.92) were associated with a decreased frequency of reported OASIS. Obesity decreased the risk of OASIS (aRR 0.90 95% CI 0.87–0.94), but only after adjusting for foetal birth weight. Previous caesarean section increased the risk of OASIS (aRR 1.41; 95% CI 1.36–1.47). Conclusion. Primiparity, instrumental delivery and high birth weight increased the risk of OASIS. Risk factors including BMI, height, age, smoking, maternal education, ethnicity and previous caesarean section also contribute to the overall risk of OASIS. Keywords. Obstetric sphincter injuries, risk factors, pregnancy.

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Evaluation of Suzor forceps training by studying obstetric anal sphincter injuries: a retrospective study

BMC Pregnancy and Childbirth ◽

10.1186/s12884-020-03358-0 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Perrine COSTE MAZEAU ◽

Nedjma BOUKEFFA ◽

Nathalie TICAUD BOILEAU ◽

Samantha HUET ◽

Maud TRAVERSE ◽

...

Keyword(s):

Risk Factors ◽

Body Mass Index ◽

Retrospective Study ◽

Observational Study ◽

Anal Sphincter ◽

University Hospital ◽

Obstetric Anal Sphincter Injuries ◽

Fourth Degree ◽

Perineal Tears ◽

Vacuum Extractor

Abstract Background Instrumental deliveries are an unavoidable part of obstetric practice. Dedicated training is needed for each instrument. To identify when a trainee resident can be entrusted with instrumental deliveries by Suzor forceps by studying obstetric anal sphincter injuries. Methods A French retrospective observational study of obstetric anal sphincter injuries due to Suzor forceps deliveries performed by trainee residents was conducted from November 2008 to November 2016 at Limoges University Hospital. Perineal lesion risk factors were studied. Sequential use of a vacuum extractor and then forceps was also analyzed. Results Twenty-one residents performed 1530 instrumental deliveries, which included 1164 (76.1%) using forceps and 89 (5.8%) with sequential use of a vacuum extractor and then forceps. Third and fourth degree perineal tears were diagnosed in 82 patients (6.5%). Residents caused fewer obstetric anal sphincter injuries after 23.82 (+/− 0.8) deliveries by forceps (p = 0.0041), or after 2.36 (+/− 0.7) semesters of obstetrical experience (p = 0.0007). No obese patient (body mass index> 30) presented obstetric anal sphincter injuries (p = 0.0013). There were significantly fewer obstetric anal sphincter injuries after performance of episiotomy (p < 0.0001), and more lesions in the case of the occipito-sacral position (p = 0.028). Analysis of sequential instrumentation did not find any additional associated risk. Conclusion Training in the use of Suzor forceps requires extended mentoring in order to reduce obstetric anal sphincter injuries. A stable level of competence was found after the execution of at least 24 forceps deliveries or after 3 semesters (18 months) of obstetrical experience.

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