Obstetric anal sphincter injury in the second birth after perineal wound complication in the first birth: A nationwide register cohort study.

OBJECTIVE: To investigate whether perineal wound complications in the first birth, alone or in conjunction with obstetric anal sphincter injury (OASI), is associated with an increased risk of OASI in the second birth. DESIGN: Nationwide population-based cohort study. SETTING: Sweden. POPULATION: Women (n = 411 317) with first and second singleton vaginal births in Sweden, 2001-2019. METHODS: Data on diagnostic codes and surgical procedures were retrieved from the Swedish Medical Birth Register and the Swedish Patient Register. A perineal wound complication was defined as wound infection, dehiscence or perineal haematoma within 2 months of childbirth. MAIN OUTCOME MEASURES: Associations between wound complications in the first birth and OASI in the second birth were investigated with logistic regression and presented as adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs). RESULTS: In total, 2619 (0.6%) women had a wound complication in the first birth, and 5318 (1.3%) had an OASI in the second birth. Women with a wound complication but no OASI in the first birth had more than doubled odds of OASI in the second birth (aOR 2.73, 95% CI 2.11-3.53). Women with OASI and a wound complication in the first birth had almost tenfold odds (aOR 9.97, 95% CI 6.53-15.24) of recurrent OASI. CONCLUSIONS: Perineal wound complication in the first birth increases the likelihood of OASI in a subsequent birth.

Caesarean section and anal incontinence in women after obstetric anal sphincter injury: A systematic review and meta-analysis.

BACKGROUND: Approximately 50% women who give birth after obstetric anal sphincter injury (OASI) develop anal incontinence (AI) over their lifetime. OBJECTIVE: To evaluate current evidence for a protective benefit of planned caesarean section (CS) to prevent AI after OASI. SEARCH STRATEGY: MEDLINE/PubMed, Embase 1974-2024, CINAHL and Cochrane to 7 February 2024 (PROSPERO CRD42022372442). SELECTION CRITERIA: All studies reporting outcomes after OASI and a subsequent birth, by any mode. DATA COLLECTION AND ANALYSIS: Eighty-six of 2646 screened studies met inclusion criteria, with nine studies suitable to meta-analyse the primary outcome of 'adjusted AI' after OASI and subsequent birth. Subgroups: short-term AI, long-term AI, AI in asymptomatic women. SECONDARY OUTCOMES: total AI, quality of life, satisfaction/regret, solid/liquid/flatal incontinence, faecal urgency, AI in women with and without subsequent birth, change in AI pre- to post- subsequent birth. MAIN RESULTS: There was no evidence of a difference in adjusted AI after subsequent vaginal birth compared with CS after OASI across all time periods (OR = 0.92, 95% CI 0.72-1.20; 9 studies, 2104 participants, I2 = 0% p = 0.58), for subgroup analyses or secondary outcomes. There was no evidence of a difference in AI in women with or without subsequent birth (OR = 1.00 95% CI 0.65-1.54; 10 studies, 970 participants, I2 = 35% p = 0.99), or pre- to post- subsequent birth (OR = 0.79 95% CI 0.51-1.25; 13 studies, 5496 participants, I2 = 73% p = 0.31). CONCLUSIONS: Due to low evidence quality, we are unable to determine whether planned caesarean is protective against AI after OASI. Higher quality evidence is required to guide personalised decision-making for asymptomatic women and to determine the effect of subsequent birth mode on long-term AI outcomes.

Obstetric anal sphincter injuries during instrumental vaginal delivery: An observational study based on 18-years of real-world data.

OBJECTIVE: To determine the prevalence and secular trends of obstetric anal sphincter injuries (OASIS) in vacuum and forceps deliveries in Norway, both with and without episiotomy. DESIGN: Population-based real-world data collected during 2001-2018. SETTING: Medical Birth Registry Norway. POPULATION OR SAMPLE: Nulliparous women with singleton foetuses in a cephalic presentation delivered by either vacuum or forceps (n = 70 783). METHODS: Logistic regression analyses were applied to the OASIS prevalence in six 3-year time periods. Both crude odds ratios and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were determined. MAIN OUTCOME MEASURES: OASIS prevalence. RESULTS: The OASIS prevalence in vacuum and forceps deliveries decreased from 14.8% during 2001-2003 to 5.2% during 2016-2018. The overall reduction between the first and last 3-year time period was 61% (aOR = 0.39, 95% CIs = 0.35-0.43). The only exception to this decreasing trend in OASIS was found in forceps deliveries performed without an episiotomy. The OASIS prevalence was approximately twofold higher in forceps compared to vacuum deliveries (aOR = 1.92, 95% CIs = 1.79-2.05). Performing either a mediolateral or lateral episiotomy was associated with a 45% decrease in the prevalence of OASIS relative to no episiotomy (aOR = 0.55, 95% CIs = 0.52-0.58). CONCLUSIONS: Opting for vacuum rather than forceps delivery in conjunction with a mediolateral or lateral episiotomy could significantly lower the OASIS prevalence in nulliparous women.

Irritable bowel syndrome worsens faecal incontinence after primary repair of major obstetric anal sphincter injuries.

AIM: Obstetric anal sphincter injuries (OASIS) occur in approximately 3%-6% of vaginal deliveries and are the leading risk factor for late-onset faecal incontinence, which is an underdiagnosed pathology. The aim of this work was to use a validated scoring system to quantify the effect of irritable bowel syndrome (IBS) on the severity of faecal incontinence symptoms after primary repair of major OASIS (Grade IIIb-IV). METHOD: A prospective cohort study was performed on all women who underwent primary repair of major OASIS over a 6-year period. They were assessed with ultrasonography within 12 weeks. Two control groups (who did not have OASIS) were women who underwent elective caesarean section and primigravid women. Questionnaires were sent at least 12 months after delivery, or at first consultation for primigravids, which generated the main outcome measures: Cleveland Clinic faecal incontinence severity scores and the presence of IBS based on Rome III criteria. RESULTS: There was a total of 211 patients included in the three groups and the mean follow-up time was 26 months after sphincter repair. Ultrasonographic sphincter defects were detected in 37% but did not affect the faecal incontinence score (p = 0.47), except in patients with IBS. Within each group, patients with IBS had significantly worse faecal incontinence than those without. Women with both OASIS and IBS had the most severe faecal incontinence scores. CONCLUSION: OASIS has a limited negative effect on faecal incontinence, independent of whether residual ultrasonographic sphincter defects are present. However, the presence of IBS has a significant compounding effect on faecal incontinence in OASIS patients. The effect of IBS on faecal incontinence is also notable in caesarean section patients and primigravids, suggesting that IBS is an independent risk-factor that should have its place in predelivery assessment and counselling.

UK survey of colorectal surgeons on the management of acute obstetric anal sphincter injuries.

AIM: The role of colorectal surgeons in the management of acute obstetric anal sphincter injury (OASI) is an ongoing debate. Their expertise in operating in the anorectal region lends itself to assisting in OASI repair. The aim of this study was to establish the current involvement and recommended management of acute OASI by colorectal surgeons. METHOD: An online survey of consultant colorectal surgeons was sent to members of the Pelvic Floor Society to assess current involvement in acute OASI management and repair. RESULTS: Forty completed surveys were collated and analysed. Sixty-five per cent of respondents had seen an acute OASI since being a consultant and 50% stated they were involved in the repair of OASI less than once per year. 37.5% felt that a de-functioning stoma was still necessary sometimes. Many agreed with current guidelines for OASI repair in terms of antibiotics, laxatives and follow-up. CONCLUSIONS: Colorectal surgeons have varied opinions on the management of OASI. We suggest that multidisciplinary training of obstetricians and colorectal surgeons could lead to more collaboration regarding the management of women with acute OASI.

Obstetric Anal Sphincter Injury Care Bundle: A Quality Improvement Initiative.

INTRODUCTION AND HYPOTHESIS: The objective was to implement an evidence-based peri-partum care bundle for women sustaining obstetric anal sphincter injuries and to evaluate compliance with recommendations for antibiotics use, repair in the operating room, and follow-up before and after implementation. METHODS: This project was reviewed by the Institutional Review Board and determined to be exempt. A clinical care bundle containing education and standardized orders in the electronic medical record was implemented. Characteristics of pre- (October 2017 to September 2019) and post-intervention (October 2019 to August 2021) cohorts were compared and compliance with recommendations for antibiotics use, surgical repair location, and follow-up were evaluated. Chi-squared, Fisher's exact, ANOVA F, and Kruskal-Wallis tests were performed, as indicated. Significance level was p < 0.05. RESULTS: A total of 185 cases were identified. Seventy-five percent of women were nulliparous. Mean gestational age was 39 weeks. Pre- and post-intervention groups did not differ in age, BMI, race, parity, gestational age, comorbidities, birthweight, or delivery type. Ninety-eight cases were identified pre-implementation. Eighty-six (88%) had third-degree lacerations. Post-implementation, 87 cases were identified. Seventy (80%) had third-degree lacerations (p = 0.17). Recommended antibiotic-type use improved from 35% pre-implementation to 93% post-implementation (p < 0.001). Repair in the operating room was similar pre-implementation and post-implementation (16.0% vs 12.6%, p = 0.48). Post-partum follow-up within 2 weeks improved from 16.3% pre-implementation to 52.8% post-implementation and mean time to follow-up was shorter post-implementation than pre-implementation (18 vs 33 days; both p < 0.001). CONCLUSIONS: Implementation of an evidence-based peri-partum care bundle resulted in standardization of care in accordance with established recommendations. Compliance with recommendations for surgical repair in the operating room remained unchanged.

Family medicine physician identification of obstetric lacerations: a US national survey.

INTRODUCTION AND HYPOTHESIS: We evaluated family medicine obstetric providers' identification and categorization of vaginal delivery lacerations in the USA. We hypothesized that there would be inaccuracy in family medicine physicians' identification of vaginal delivery injuries, similar to our previous studies of midwives and obstetricians (OBs). METHODS: We included clinically active physicians who attended deliveries within 2 years and evaluated their identification and categorization of delivery lacerations using descriptive text and visual images. We asked about their education on this topic and how they document lacerations in the labor and delivery record. RESULTS: We analyzed 250 completed responses (70% of opened surveys). Fifty-five percent of respondents characterized their obstetric laceration training as "good" or "excellent" and half previously had education on obstetric lacerations. The median accuracy overall for the classification and identification of perineal lacerations was 78% (IQR 56-91%). Respondents frequently mischaracterized nonperineal lacerations. Few respondents (36%) reported using the third-degree injury subclassification system. In adjusted analysis, the highest scoring respondents were board certified in family medicine, with fewer years in practice, and a higher obstetric volume. CONCLUSIONS: Obstetric laceration diagnoses may be inaccurate, which could influence perinatal quality and patient outcomes. We found gaps in knowledge similar to previous reports on midwives and obstetricians in the USA. These data suggest a need for increased education and training on obstetric injuries, perhaps especially for physicians with less obstetric activity. Improved categorization and identification of vaginal delivery trauma can impact management and improve women's postpartum care and long-term pelvic floor outcomes.

Obstetric Anal Sphincter Injury After Episiometer-Guided Versus Conventional Episiotomy in Instrumental Deliveries: A Randomized Controlled Trial.

INTRODUCTION AND HYPOTHESIS: Guidelines recommend episiotomy for instrumental vaginal delivery with an optimal incision angle of 60° to protect the anal sphincter. The "Episiometer" is a new device promising a 60° incision angle. We compared the incidence of obstetric anal sphincter injury (OASI) and post-repair suture angle of episiotomies made with conventional "eyeballing" versus Episiometer guided during instrumental delivery. METHODS: We conducted this randomized controlled trial in a tertiary care teaching institute in southern India after ethical committee approval, trial registration, and informed consent. We randomized (block) 328 pregnant women aged 18 years and above with term, singleton fetuses delivered by instruments into Episiometer-guided (164) or conventional episiotomy (164) groups (allocation concealed). We compared the OASI (identified clinically) and the suture angle measured from the midline (assessor blinded) in the two groups. We followed up on the subjects at 6 and 12 weeks to assess perineal pain and fecal/flatus incontinence. RESULTS: The incidence of OASI of 0.61% in the Episiometer group was significantly lower compared with 4.88% in the eyeballing group (Chi-squared = 5.6; p = 0.02; adjusted risk ratio = 5.9; CI 0.7-46.1; p = 0.09). A significantly higher proportion of subjects (59.1%) in the Episometer group had a post-suture angle between 36 and 40° compared with 36.6% in the eyeballing group (Chi-squared = 21.8, p < 0.001). We found no significant difference in the perineal pain or Wexner score during follow-up. CONCLUSION: The Episiometer-guided episiotomy during instrumental delivery resulted in a significantly higher suture angle and lower obstetric anal sphincter injuries than with conventional eyeballing.

Factors Associated with Obstetric Anal Sphincter Injury During Vacuum-Assisted Vaginal Delivery.

INTRODUCTION AND HYPOTHESIS: Obstetric anal sphincter injury (OASI) is a major complication associated with vacuum-assisted vaginal delivery (VAVD). The aim of this study was to evaluate risk factors related to vacuum extraction that are associated with OASI. METHODS: This was a case-control study performed at a tertiary university teaching hospital. Included were patients aged 18-45 years who had a singleton pregnancy resulting in a live, term, VAVD. The study group consisted of women diagnosed with OASI following vacuum extraction. The control group included women following VAVD without OASI. Matching at a ratio of 1:2 was performed. Groups were compared regarding demographic, obstetric. and labor-related parameters, specifically focusing on variables related to the vacuum procedure itself. RESULTS: One hundred and ten patients within the study group and 212 within the control group were included in the final analysis. Patients in the OASI group were more likely to undergo induction of labor, use of oxytocin during labor, increased second stage of labor, higher likelihood of the operator being a resident, increased number of pulls, procedure lasting under 10 min, occipito-posterior head position at vacuum initiation, episiotomy, increased neonatal head circumference, and birthweight. Multivariate logistic regression analysis revealed that increased week of gestation (OR 1.67, 95% CI 1.25-2.22, p < 0.001), unsupervised resident performing the procedure (OR 4.63, 95% CI 2.17-9.90), p < 0.001), indication of VAVD being fetal distress (OR 2.72, 95% CI 1.04-7.10, p = 0.041), and length of procedure under 10 min (OR 4.75, 95% CI 1.53-14.68, p = 0.007) were associated with OASI. Increased maternal age was associated with lower risk of OASI (OR 0.9, 95% CI 0.84-0.98, p = 0.012). CONCLUSIONS: When performing VAVD, increased week of gestation, unsupervised resident performing the procedure, fetal distress as vacuum indication, and vacuum procedure under 10 min were associated with OASI. In contrast, increased maternal age was shown to be a protective factor.

Anal incontinence following obstetric anal sphincter injury: Is there a difference between subtypes? A systematic review.

AIMS: Obstetric anal sphincter injury (OASI) is associated with long-term anal incontinence (AI). We aimed to address the following questions: (a) are women with major OASI (grade 3c and 4) at higher risk of developing AI when compared to women with minor OASI (grade 3a and 3b)? (b) is a fourth-degree tear more likely to cause AI over a third-degree tear? METHODS: A systematic literature search from inception until September 2022. We considered prospective and retrospective cohort studies, cross-sectional and case-control studies without language restrictions. The quality was assessed by the Newcastle-Ottawa Scale and the Joanna Briggs Institute critical appraisal checklist. Risk ratios (RRs) were calculated to measure the effect of different grades of OASI. RESULTS: Out of 22 studies, 8 were prospective cohort, 8 were retrospective cohort, and 6 were cross-sectional studies. Length of follow-up ranged from 1 month to 23 years, with the majority of the reports (n = 16) analysing data within 12-months postpartum. Third-degree tears evaluated were 6454 versus 764 fourth-degree tears. The risk of bias was low in 3, medium in 14 and high in 5 studies, respectively. Prospective studies showed that major tears are associated with a twofold risk of AI for major tears versus minor tears, while retrospective studies consistently showed a risk of fecal incontinence (FI) which was two- to fourfold higher. Prospective studies showed a trend toward worsening AI symptoms for fourth-degree tears, but this failed to reach statistical significance. Cross-sectional studies with long-term (≥5 years) follow-up showed that women with fourth-degree tear were more likely to develop AI, with an RR ranging from 1.4 to 2.2. Out of 3, 2 retrospective studies showed similar findings, but the follow-up was significantly shorter (≤1 year). Contrasting results were noted for FI rates, as only 5 out of 10 studies supported an association between fourth-degree tear and FI. CONCLUSIONS: Most studies investigate bowel symptoms within few months from delivery. Data heterogeneity hindered a meaningful synthesis. Prospective cohort studies with adequate power and long-term follow-up should be performed to evaluate the risk of AI for each OASI subtype.

Underdiagnosis of internal anal sphincter trauma following vaginal delivery.

OBJECTIVE: Damage to the anal sphincter during childbirth remains the leading cause of fecal incontinence in women. Defects in the internal (IAS) or external anal sphincter, alongside symptoms and sphincter tone, will generally dictate the suggested mode of delivery in any successive pregnancy. This study aimed to examine using endoanal ultrasonography the prevalence of IAS damage in women referred with Grade-3a or -3b obstetric anal sphincter injury (OASI) in a tertiary-referral perineal clinic. METHODS: This was a retrospective observational study of all women referred to a tertiary-referral perineal clinic after primary repair of OASI (Grade 3a-c, 4) diagnosed for the first time following vaginal delivery between January 2016 and December 2019, inclusive. Women were assessed using the Wexner bowel continence questionnaire, digital examination of sphincter tone and endoanal ultrasound. Injuries in each sphincter were classified as a scar (≤ 30°) or defect (> 30-90° or > 90°) on endoanal imaging in the axial plane. RESULTS: In total, 615 women were referred following primary repair of OASI. Sonographic evidence of damage to the IAS was seen in 9.1% (46/506) of women diagnosed with a Grade-3a/3b injury. In women referred with a Grade-3a/3b tear, symptom scores were statistically higher (P = 0.025) in those with an IAS defect > 30° compared to those with an intact or scarred IAS, although the median score was zero in both groups. The proportion of women in each group with severe symptoms (score > 9) was similar (2.6% vs 6.5%; P = 0.148). Among women referred with a Grade-3a/3b tear, sphincter tone was reduced more frequently in those with a defect of the IAS than in those with an intact or scarred IAS (52.2% vs 11.7%; odds ratio, 8.14 (95% CI, 4.26-15.67); P < 0.001). Regardless of the reason for referral, women with reduced sphincter tone on rectal examination were four times as likely to have had an IAS defect > 30° than were those with normal resting tone (risk ratio, 4.58 (95% CI, 3.25-6.45); P < 0.001). CONCLUSIONS: One in 11 women diagnosed with a Grade-3a or -3b tear have evidence of damage to their IAS on endoanal ultrasound. Damage to this muscle is linked to fecal incontinence in women and can have a significant impact on the planning of any future deliveries. This study highlights the importance of established perineal clinics with access to ultrasound. Nonetheless, if reduced sphincter tone is felt on rectal examination, a clinician should have a high index of suspicion for an occult IAS injury. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Predictive factors for obstetric anal sphincter injury in primiparous women: systematic review and meta-analysis.

OBJECTIVES: The primary objective was to perform a systematic review of predictive factors for obstetric anal sphincter injury (OASI) occurrence at first vaginal delivery, with the diagnosis made by ultrasound (US-OASI). The secondary objective was to report on incidence rates of sonographic anal sphincter (AS) trauma, including trauma that was not clinically reported at childbirth, among the studies providing data for our primary objective. METHODS: We conducted a systematic search of MEDLINE, EMBASE, Web of Science, CINAHL, The Cochrane Library and ClinicalTrials.gov databases. Both observational cohort studies and interventional trials were eligible for inclusion. Study eligibility was assessed independently by two authors. Random-effects meta-analyses were performed to pool effect estimates from studies reporting on similar predictive factors. Summary odds ratio (OR) or mean difference (MD) is reported with 95% CI. Heterogeneity was assessed using the I2 statistic. Methodological quality was assessed using the Quality in Prognosis Studies tool. RESULTS: A total of 2805 records were screened and 21 met the inclusion criteria (16 prospective cohort studies, three retrospective cohort studies and two interventional non-randomized trials). Increasing gestational age at delivery (MD, 0.34 (95% CI, 0.04-0.64) weeks), shorter antepartum perineal body length (MD, -0.60 (95% CI, -1.09 to -0.11) cm), labor augmentation (OR, 1.81 (95% CI, 1.21-2.71)), instrumental delivery (OR, 2.13 (95% CI, 1.13-4.01)), in particular forceps extraction (OR, 3.56 (95% CI, 1.31-9.67)), shoulder dystocia (OR, 12.07 (95% CI, 1.06-137.60)), episiotomy use (OR, 1.85 (95% CI, 1.11-3.06)) and shorter episiotomy length (MD, -0.40 (95% CI, -0.75 to -0.05) cm) were associated with US-OASI. When pooling incidence rates, 26% (95% CI, 20-32%) of women who had a first vaginal delivery had US-OASI (20 studies; I2 = 88%). In studies reporting on both clinical and US-OASI rates, 20% (95% CI, 14-28%) of women had AS trauma on ultrasound that was not reported clinically at childbirth (16 studies; I2 = 90%). No differences were found in maternal age, body mass index, weight, subpubic arch angle, induction of labor, epidural analgesia, episiotomy angle, duration of first/second/active-second stages of labor, vacuum extraction, neonatal birth weight or head circumference between cases with and those without US-OASI. Antenatal perineal massage and use of an intrapartum pelvic floor muscle dilator did not affect the odds of US-OASI. Most (81%) studies were judged to be at high risk of bias in at least one domain and only four (19%) studies had an overall low risk of bias. CONCLUSION: Given the ultrasound evidence of structural damage to the AS in 26% of women following a first vaginal delivery, clinicians should have a low threshold of suspicion for the condition. This systematic review identified several predictive factors for this. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Diagnosis, management and training in perineal trauma: a UK national survey of obstetricians.

INTRODUCTION AND HYPOTHESIS: Perineal trauma during vaginal delivery is very common. Training in diagnosis and repair of trauma, including obstetric anal sphincter injuries, varies in the UK. We aimed to investigate the current knowledge and training received by obstetric physicians. METHODS: A national, validated survey was conducted online, using Qualtrics. The National Trainees Committee distributed the survey. It was also sent directly to consultants via email. RESULTS: A total of 302 physicians completed the survey and were included in the analysis. 3.9% of participants described their training in obstetric perineal trauma as "very poor" or "poor". 20.5% said they have not received training. 8.6% of physicians practising for more than 10 years had not had training for over 10 years. 70.5% responded "somewhat agree" or "strongly agree" when asked if they would like more training. Identification of first, second, third-, and fourth-degree tears from images and descriptions was very good (more than 80% correct for all categories). Classification of other perineal trauma was less consistent, with many incorrectly using the Sultan Classification. "Manual perineal support" and "Controlled or guided delivery" were the most frequently selected methods for the prevention of obstetric anal sphincter injury (OASI). CONCLUSIONS: Training experience for physicians in obstetric perineal trauma varies. Further improvement in training and education in perineal trauma, particularly in OASI, is needed for physicians. Perineal trauma that is not included in the Sultan Classification is often misclassified.

Pelvic floor healing milestones after obstetric anal sphincter injury: a prospective case control feasibility study.

INTRODUCTION AND HYPOTHESIS: Severe perineal tears can predict bothersome pelvic floor disorders later in life. We have a poor understanding of pelvic floor changes during the third trimester and the first few postpartum months. We aimed to compare women with severe perineal trauma during childbirth with women who experienced minimal trauma, for condition-specific quality of life, sexual function, mental health and overall quality of life in the first 6 months postpartum. METHODS: We recruited primiparous women with third- or fourth-degree tears (obstetric anal sphincter injuries, OASIS) and age-matched controls with no tears or first-degree tears in the immediate postpartum period. Participants completed validated questionnaires at baseline, 2, 4 and 6 months postpartum. Mixed effects linear regression or quantile regression adjusted for baseline score were used to compare the groups as appropriate. RESULTS: A total of 74 women completed at least one questionnaire (35 OASIS, 39 controls). Both groups had similar demographics. Women with OASIS tended to have worse Pelvic Floor Distress Index-40 scores at month 2; median scores were similar in the two groups by month 6. They also had significantly lower Female Sexual Function Index scores (mean difference: -6.1; 95% CI: -11.9, -0.2, p=0.043) at month 2. There were no mental health group differences and quality of life improved over time, mainly in the OASIS group. Six-month participant attrition rate was 52%. CONCLUSIONS: Women with OASIS encounter specific pelvic floor challenges during the first 6 months postpartum. Although our recruitment rate was high, the attrition rate was also high, demonstrating challenges with retention of postpartum women into longitudinal research.

When does oasis cause de novo pelvic floor dysfunction? role of the surgeon's skills.

INTRODUCTION AND HYPOTHESIS: Minorly skilled gynecologists are less likely to repair obstetric anal sphincter injuries (OASIS), and this can lead to higher rate of de novo onset of pelvic floor dysfunction (PFD). The aim of this study was to understand the impact of surgeon skills in OASIS repair on de novo incidence of PFDs. METHODS: An observational prospective cohort study performed between January 2019 and December 2020. We included 116 women with OASIS. At 6-weeks from delivery, women were divided into two groups in relation to the onset of PFDs. Characteristics were compared; categorical and continuous variables were assessed with chi-squared test and the Mann-Whitney rank-sum test respectively. Factors involved in PFDs development were analysed with explorative univariate analysis; significant (p<0.05) or approaching significance (p≤0.10) variables were included in multivariable analysis. RESULTS: Seventy-six women (76/116; 65.5%) reported at least one PFD symptom and anal incontinence was the most prevalent (44.73%; 34/76). OASIS management by a skilled gynaecologist resulted protective for PFDs [aOR 0.33 (0.13-0.61)]. Skilled surgeon reported fewer PFDs than less skilled surgeon (4% vs 82.4%; p<0.0001). Operative delivery was more performed (32.5% vs 15.8%; p= 0.03) and severe OASIS resulted more prevalent (60% vs 17.1%; p<0.0001) among women without PDFs, even if these didn't affect the incidence of de novo PFDs [aOR 1.03 (0.23-1.45) and 0.83 (0.13-1.45), respectively]. CONCLUSIONS: Surgeons skilled in OASIS repair resulted the only protective factor for incidence of de novo PFDs in women with OASIS at 6 weeks of follow up. Improvement of training in OASIS repair is necessary.

In vivo assessment of the elastic properties of the external anal sphincter in term pregnant women using shear wave elastography.

INTRODUCTION AND HYPOTHESIS: The objective was to assess the intraobserver intersession and interobserver intrasession reliability of shear wave elastography applied to the external anal sphincter in term pregnant women. METHODS: This prospective study involved nulliparous pregnant women at 37 weeks or more with two visits (V1: one observer; V2 two observers) planned within a 12-h to 7-day interval. Measurements were performed using an Aixplorer V12® device with an SL 18-5 linear probe using a transperineal approach, allowing a measurement of the shear modulus (SM) in kPa. Measures were performed at rest, Valsalva maneuver, and maximal contraction. Reliability was assessed using the intraclass correlation coefficient (ICC). The study was approved by an ethics committee (ID RCB: 2020-A00764-65). RESULTS: A total of 37 women were included. Intraobserver reliability was excellent at rest (ICC = 0.91 [0.84-0.95) and good during the Valsalva maneuver (ICC = 0.83 [0.72-0.90]) and contraction (ICC = 0.85 [0.75-0.91]). Interobserver reliability was good at rest (ICC = 0.79 [0.66-0.87]) and during Valsalva (ICC = 0.84 [0.73-0.90]), but moderate during contraction (ICC = 0.70 [0.53-0.82]). CONCLUSIONS: Shear wave elastography is a reliable tool for assessing the elastic properties of the external anal sphincter in term pregnant women.

Morphological differences in the female anal sphincter complex between endoanal and exoanal ultrasound.

INTRODUCTION AND HYPOTHESIS: This study was aimed at describing the morphological characteristics of the normal female anal sphincter complex (ASC) by high-resolution transperineal ultrasound (TPUS) and endoanal ultrasound (EAUS). METHODS: Thirty volunteers, including 19 nulliparous and 11 women who had only given birth by Cesarean section, were recruited. The ASC was shown in a set of five slices by EAUS and 8 slices by TPUS. EAUS slices 1 and 5 matched TPUS slices 1 and 8; EAUS slices 2, 3, and 4 were approximately at the levels of TPUS slices 3, 5, and 7. The anterior and lateral EAS and IAS thicknesses were measured and the two methods were compared. RESULTS: The median age was 29 years. The mean body mass index (BMI) was 20.6 kg/m2. All measured values obtained by TPUS were normally distributed. The EAS thickness on EAUS slice 2 and the IAS thickness on EAUS slices 2 and 3 were not normally distributed. The mean anterior EAS thickness was 2.51 mm, 2.96 mm, and 3.53 mm in slices 3, 5, and 7 on TPUS and was significantly thinner than that in slices 2 (2.62 mm), 3 (3.77 mm), and 4 (4.62 mm) on EAUS. In contrast, the IAS was markedly thicker on TPUS. The ratio of sphincter thickness anteriorly to laterally was similar using the two methods. CONCLUSIONS: The morphological characteristics of EAS shown by TPUS and EAUS were similar. EAS was thinner, and IAS was thicker on TPUS. The IAS seems to be distorted on endoanal imaging.

Re-evaluation of modifiable risk factors for obstetric anal sphincter injury in a real-world setting.

INTRODUCTION AND HYPOTHESIS: The objective was to identify modifiable risk factors for obstetric anal sphincter injury (OASI) in primiparous women. METHODS: This was a retrospective cohort study of primiparous women with a singleton vaginal delivery. Main outcome measures were incidence of OASI and odds ratios for possible risk factors: maternal age, body mass index and height, fetal birthweight and head circumference, gestational age, epidural analgesia, mediolateral episiotomy, and instrumental deliveries. Univariate and multivariate logistic regressions were performed using forward methods for variable selection. RESULTS: Of 19,786 primiparous women with a singleton vaginal delivery, 369 sustained an OASI (1.9%). Risk factors were identified: vacuum extraction (adjusted OR 2.06, 95% CI, 1.59-2.65, p < 0.001), increased fetal weight (aOR 1.06, 95% CI, 1.02-1.11, p = 0.002, per 100-g increments); head circumference (aOR 1.24, 95% CI, 1.13-1.35, p < 0.001, per 1-cm increments); gestational week (aOR 1.11, 95% CI, 1.02-1.2, p = 0.012, per week). Protective factors: mediolateral episiotomy (aOR 0.75, 95% CI, 0.59-0.94, p = 0.013) particularly in vacuum deliveries (aOR 0.50, 95% CI, 0.29-0.97, p = 0.040); epidural analgesia (aOR 0.64, 95% CI, 0.48-0.84, p = 0.001); maternal height ≥157 cm (aOR 0.97, 95% CI, 0.96-0.98, p = 0.006, risk decreases by 2.6% per 1 cm increase in height). CONCLUSIONS: Mediolateral episiotomy was protective against OASI in both spontaneous and instrumental deliveries of primiparae. Increased fetal weight and large fetal head circumference, particularly in short women, were significant risk factors. These findings support the performance of ultrasound to acquire updated fetal measures before admission to the labor ward.

The association between episiotomy or OASIS at vacuum extraction in nulliparous women and subsequent prelabor cesarean delivery: A nationwide observational study.

INTRODUCTION: Severe perineal injuries at childbirth affect women's postnatal health, including future childbirths. First births with vacuum extraction carry an increased risk of obstetric anal sphincter injuries (OASIS). Lateral or mediolateral episiotomy at vacuum extraction may decrease the risk of OASIS. Our aim was to assess whether lateral or mediolateral episiotomy, or OASIS, at vacuum extraction in nulliparous women is associated with prelabor cesarean delivery in the subsequent childbirth. MATERIAL AND METHODS: This is a nationwide observational study using data from the Swedish Medical Birth Register, including women having a first birth with vacuum extraction and a second birth in 2000-2014. Both births were live, single, cephalic, ≥34 gestational weeks without malformations. The association between episiotomy or OASIS in the first birth and prelabor cesarean delivery in the second birth was examined using univariate and multivariate logistic regression with inverse probability of treatment weighting, and interaction analysis. Main outcome measure was prelabor cesarean delivery in the second birth. RESULTS: In total, 44 656 women with vacuum extraction at their first birth were included. The rate of prelabor cesarean delivery in the second birth was 5.9% (824 of 13 950) in women with episiotomy, compared with 6.0% (1830 of 30 706) in women without episiotomy. Thus, women with episiotomy did not have an increased risk of prelabor cesarean delivery (adjusted odds ratio [aOR] 1.00, 95% confidence interval [95% CI] 0.83-1.20) compared with women without episiotomy. For comparison, the rate of prelabor cesarean delivery in the second birth was 20.6% (1275 of 6176) in women with OASIS, compared with 3.6% (1379 of 38 480) in women without OASIS (aOR 6.57, 95% CI 5.97-7.23). There was no interaction between episiotomy and OASIS. CONCLUSIONS: Lateral or mediolateral episiotomy at vacuum extraction in nulliparous women did not increase the risk of prelabor cesarean delivery in the subsequent childbirth. OASIS increased the odds of prelabor cesarean delivery more than sixfold.

Use of endoanal ultrasound in detecting obstetric anal sphincter injury immediately after birth.

INTRODUCTION: Obstetric anal sphincter injury (OASI) complicates around 5% of deliveries in primiparas. The study objective was to assess the utility of three-dimensional endoanal ultrasonography (3D-EAUS) in the diagnosis of OASI. MATERIAL AND METHODS: The present study was designed to mirror screening settings with an unselected cohort of nulliparous women. All enrolled patients underwent clinical examination of the perineum by the caregiver, and 3D-EAUS was conducted. Post-processing of ultrasonography volume data was performed by an experienced colorectal surgeon who was blinded to all other data. The sensitivity, specificity, negative predictive value, and positive predictive value of 3D-EAUS in the diagnosis of OASI was evaluated. The trial is registered at ISCRTN: 18006769. RESULTS: A total of 680 scans were performed, of which 18.5% were judged as "non-assessable", resulting in 554 assessable recordings. Sphincter defects were observed in 12.8% of all assessable recordings on 3D-EAUS (n = 71). With clinical examination set as the reference standard, ultrasound sensitivity in the diagnosis of OASI was 30.4%, whereas its specificity was 87.9%. The negative predictive value was 96.7% and the positive predictive value was only 9.9%. Comments were left on 175 examinations, of which 74% referred to the management of the examination. CONCLUSIONS: Using 3D-EAUS in a maternity ward is demanding because staff generally have little experience in endoanal ultrasound, which contributes to difficulties in obtaining good image quality. When 3D-EAUS is performed to mirror screening settings, it adds no convincing diagnostic power to clinical examination in the diagnosis of OASI.