Obstetric Anal Sphincter Tears Research Articles

Risk of obstetric anal sphincter tear among primiparous women with a history of female genital mutilation, giving birth in Sweden.

Female genital mutilation (FGM) includes a range of procedures involving partial or total removal of the external female genitalia. It is a harmful procedure that violates human rights of girls and women. FGM has been associated with obstetric anal sphincter injury (OASI), among other adverse obstetric complications. However, the obstetric outcomes in high-income countries are not clear. The aim of this study was to compare the risk of OASI among primiparous women, with and without a history of FGM, giving birth in Sweden. A population-based cohort-study based on data from the Swedish Medical Birth Register during the period 2014-2018. The study included primiparous women with singleton term pregnancies. We compared the risk, using multivariable logistic regression, of our main outcome OASI between women with a diagnosis of FGM and women without a diagnosis of FGM. Secondary outcomes included episiotomy and instrumental vaginal delivery. A total of 239,486 primiparous women with a term singleton pregnancy were identified. We included 1,444 women with a diagnosis of FGM and 186,294 women without a diagnosis of FGM in our analysis. The overall rate of OASI was 3% in our study population. By using multivariable logistic regression analysis, we found that women with a diagnosis of FGM had a significantly increased odds ratio (OR) of OASI (OR 2.69, 95%CI: 2.14-3.37) compared to women without a diagnosis of FGM. We also found an association between FGM and instrumental delivery as well as the use of episiotomy. Women with a history of FGM have an almost tripled risk of OASI in comparison with women without FGM, when giving birth in a Swedish setting. Increased knowledge and awareness regarding FGM, and its potential health implications is crucial in order to minimise the risk of OASI among women with FGM giving birth in high-income countries. A limitation in our study is the lack of information about the specific types of FGM.

Obstetric risk factors for anal sphincter trauma in a urogynecological population.

Obstetric anal sphincter tears are the single major modifiable risk factor for anal incontinence (AI) in women. We undertook a retrospective observational study in a tertiary urogynecology unit to describe the prevalence of sonographic anal sphincter defects in a urogynecological population and investigate obstetric risk factors. Files of women seen for investigation of pelvic floor disorders between January 2014 and May 2021 were reviewed. Sonographic defects of the external anal sphincter were analyzed using stored 4D ultrasound imaging data. Explanatory parameters were number of vaginal births, delivery mode, age at first vaginal birth, and birthweight of the first vaginally born baby. Of 3,037 women seen during the inclusion period, data were missing in 219, leaving 2,818. AI was reported by 508 (18%), with a mean St Marks score of 11 (1-23) and a mean bother score of 5.9 (0-10). External sphincter defects were detected in 945 women (34%), with a "residual defect" in 343 (12%). The strongest risk factors for a residual defect were first vaginal birth and forceps, with higher-order multiparity adding risk. On multivariate analysis, forceps and vaginal parity >5 remained significant predictors, as opposed to age at first birth and birthweight of the firstborn. In this observational study in urogynecological patients, 12% showed a residual EAS defect on imaging. The most obvious risk factors for the diagnosis of a residual defect on exo-anal imaging were the first vaginal birth and forceps, with higher-order vaginal parity conveying additional risk.

Decreasing the incidence of anal sphincter tears in instrumental delivery in Hudiksvall, Sweden

Purpose The primary aim of this study was to observe the change in obstetric anal sphincter tear rates in instrumental deliveries during one decade. Secondly, the changes in non-instrumental deliveries were followed. Methods Data from all deliveries at Hudiksvall Hospital, Sweden 2010–2011 and 2016–2017 were collected. The change of OASIS rate during instrumental deliveries was the most important. Statistical significances were calculated by using chi-square test, test for relative proportions, and Students t-test, where appropriate. Results The total incidence of OASIS decreased significantly (from 2.54% to 0.73%, p < .001). Even the OASIS rate in instrumental deliveries decreased substantially from 15.1% to 3.0% (p = .002) but the decrease was statistically insignificant in spontaneous deliveries (from 1.22% to 0.60%, p = .065). Conclusion Based on the results of our study the manual protection of the perineum reduces the risk of OASIS in instrumental delivery significantly.

Accuracy of clinical diagnosis of anal sphincter defect: clinical evaluation versus 3D-transperineal ultrasound.

Obstetric anal sphincter injuries (OASIS) are common and an important factor in the etiology of anal incontinence. The objective of this study was to evaluate, classify and compare the agreement of clinically diagnosed third-degree sphincter tears with 3D-transperineal ultrasound (3D-TPUS) realized within 3-7 days post-delivery. This is a retrospective observational study were 119 patients with third-degree obstetric anal sphincter tears were diagnosed and treated, 85 of those underwent a 3D-TPUS examination 3-7 days postpartum. We compared the proportion of third-degree perineal tears, classified with the clinical examination as grade 3a+b and grade 3c, with the 3D-TPUS. In 16 patients with clinically diagnosed third-degree perineal tears grade a and b, the ultrasound examination confirmed the lesion of the external anal sphincter (EAS) muscle, but in nine patients (56% of the cases) we found a lesion of the internal anal sphincter (IAS) muscle, missed by clinical examination. In the remaining 69 patients with the third-degree perineal tears grade c, the ultrasound examination confirmed both lesions (EAS and IAS muscles) in 56 women, but in 13 patients (19% of the cases) defects of the IAS muscle could not be confirmed by the ultrasound. There was moderate agreement regarding diagnosis of grade 3a+b and grade c perineal tears between ultrasound and clinical examination, so a combined use of clinical and ultrasound knowledge can improve the possibility to find a gold standard in the diagnosis of OASIS.

Delivery after an obstetric anal sphincter tear

PurposeThe present study aimed to assess the risk of obstetric anal sphincter injuries (OASIS) of a subsequent delivery after the previous OASIS in countries with low (Finland) and high rates (Norway and Sweden) of OASIS.MethodsThis population-based case–control study included women who experienced OASIS 1997–2002. 26,598 women with OASIS were included from countries with low (Finland) and high (Norway and Sweden) OASIS incidences. Each case was matched with one background-adjusted control without OASIS. A follow-up data, including all subsequent deliveries between 1998 and 2011 were then collected. Statistics significances were calculated using chi-square test, test for relative proportions and Students t test, where appropriate.ResultsOASIS in the first birth was associated with increased recurrences in subsequent births, 6.9% vs. 1.7% in Norway (p < 0.001); 4.5% vs. 0.7 (p < 0.001) in Sweden; and 2.1% vs. 0.8% in Finland (p = 0.038). In Norway, more than two deliveries occurred in 4.8% of cases and 6.2% of controls (p = 0.001), 4.2% vs. 5.1% in Sweden (p < 0.001), and 5.7% vs. 6.3% in Finland (p = 0.572). For women with OASIS in a previous delivery, the rates of cesarean deliveries in subsequent pregnancies were 16.4% (7.9% for controls) in Norway, and 16.3% (6.0% for controls) in Sweden, and 50.2% (14.2% for controls) in Finland. In all countries, the differences between cases and controls were significant (p < 0.001).ConclusionNext deliveries after OASIS are associated with increased frequency of new OASIS, more cesarean deliveries, and less subsequent deliveries in the high-risk population than women without previous OASIS.

Vaginal Birth and Pelvic Floor Trauma

Over the last two to three decades, a growing body of research has shown that vaginal childbirth is more traumatic to mothers than generally assumed. Apart from obstetric anal sphincter tears which have been extensively studied, trauma to the levator ani muscle is a form of maternal injury that is less well recognised and often undiagnosed. In the context of an increasing push towards vaginal birth, this article will review the recent literature to better inform health care providers regarding the significance of pelvic floor trauma. Imaging studies have shown that levator avulsion, where the puborectalis muscle has detached from the os pubis, occurs in up to 1/3 of vaginally primiparous women, depending on demographic factors and obstetric management. Forceps is a well-established risk factor for levator avulsion with an odds ratio of 4–5 compared to vacuum, which does not seem to convey additional risk over unassisted vaginal birth. Levator injuries are significantly associated with pelvic organ prolapse and treatment failure. Such trauma can also lead to significant psychological morbidity, up to and including post-traumatic stress disorder. Antenatal prediction does not appear feasible. Modification of obstetric practice by abandoning forceps would significantly reduce pelvic floor trauma and the future need for prolapse surgery. Vaginal childbirth is more traumatic than commonly assumed. Levator trauma is associated with significant physical and psychological morbidity. Perinatal health care providers need to understand and recognise the significance of maternal birth trauma and its potential impact on women’s health.

Impact of Selective vs Routine Midline Episiotomy and Lacerations of the Anal Sphincter

Introduction: Obstetric anal sphincter tear (OAST) is associated with anal incontinence. Episiotomy was proposed as a form of protection of the anal sphincter at delivery; however, several studies have shown that routine use of episiotomy does not reduce the risk of OAST. Objective: This study aims to analyse whether the reduction in the rate of episiotomy in a school hospital in Brazil was associated with an increase in the incidence of obstetric lacerations of the anal sphincter, in addition to associated factors. Methods: Observational, cross-sectional and retrospective study. We included all vaginal deliveries of single pregnancies, cephalic presentation, from 34 weeks of gestational age, performed in 2011-2012 (liberal episiotomy) and 2015-2016 (restricted episiotomy), and compared in relation to the rate of mediolateral episiotomy and OAST. Results: 4268 births were analysed (2043 in 2011-2012 and 2225 in 2015-2016). The episiotomy rate decreased from 59.4% to 44.2% (p ≤ 0.0001). In 2011-2012, there were 10 obstetric anal sphincter lacerations in 2043 births (0.48%), while in the period 2015-2016 there were 31 lacerations in 2225 births (1.39%). There was interaction when comparing the two periods in relation to the episiotomy and the occurrence of OAST (p ≤ 0.0001). Factors associated with OAST were labor induction and shoulder dystocia. Conclusion: There was an increase in the rate of lacerations of the anal sphincter with use of restrictive episiotomy. However, this increase occurred both in deliveries with and in deliveries without episiotomy.

3D/4D ultrasound findings compared to pelvic floor symptoms in women diagnosed with obstetric anal sphincter tear

3D/4D ultrasound findings compared to pelvic floor symptoms in women diagnosed with obstetric anal sphincter tear

Intrapartum predictors of maternal levator ani injury.

Damage to the pelvic floor during vaginal childbirth is common, and may take the form of levator avulsion or irreversible overdistension of the levator hiatus (microtrauma). Such trauma is a major risk factor for pelvic organ prolapse later in life. In this study we aimed to identify intrapartum risk factors for levator trauma. This is a retrospective analysis of data obtained in two perinatal studies on primiparous women. Between 2005 and 2014, 1148 women carrying an uncomplicated singleton pregnancy in the late third trimester were seen for 4D pelvic floor ultrasound and an interview. They were invited for a repeat assessment at three months postpartum. Of 1148 women, 871 (76%) returned for assessment at a mean of five months postpartum. The datasets of 844 women were analyzed due to missing data or concurrent pregnancy in 27. In all, 452 (54%) had a normal vaginal delivery, 102 (12%) a vacuum, 55 (6%) a forceps, and 235 (28%) a cesarean section. On multivariate analysis forceps, length of second stage and obstetric anal sphincter tears were significantly associated with levator avulsion. There were no significant predictors identified for irreversible overdistension. The use of forceps, a prolonged second stage, and obstetric anal sphincter tears were associated with levator avulsion. There were no associated intrapartum predictors for hiatal overdistension.

Residual defects of the external anal sphincter following primary repair: an observational study using transperineal ultrasound

Obstetric anal sphincter tears are common and an important factor in the etiology of anal incontinence. The objective of the study was to evaluate the prevalence of residual defects of the external anal sphincter (EAS) after primary repair of obstetric anal sphincter injury using four-dimensional (4D) transperineal ultrasound and to correlate sonographic findings of residual defects and levator avulsion with significant symptoms of anal incontinence, defined as St Mark's fecal incontinence score (SMIS) of ≥ 5. This was a retrospective observational study. One-hundred and forty women were seen after primary repair of obstetric anal sphincter tears in a dedicated perineal clinic at a tertiary hospital in Australia. They all underwent a standardized interview, and physical and 4D transperineal ultrasound examination. Mean follow-up interval was 1.9 months after delivery. Eighty-nine (64%) women had a 3a/3b tear, 28 (20%) a 3c/4(th) degree tear and 23 (16%) an unclassified 3(rd) degree tear. Thirty-five (25%) patients reported symptoms of anal incontinence. Nine had an SMIS of ≥ 5. A residual defect was found in 56 (40%) cases and levator avulsion in 27 (19%). On multivariate logistic regression, residual defects (P = 0.03; odds ratio (OR) = 6.38; 95% CI, 1.23-33.0) and levator avulsion (P = 0.047; OR = 4.38; 95% CI, 1.02-18.77) were found to be independent risk factors for anal incontinence. Residual defects of the EAS were found on transperineal ultrasound in 40% of women after primary repair of obstetric anal sphincter injuries. Although most were asymptomatic, residual anal sphincter defects and levator avulsion were associated with significant symptoms of anal incontinence as quantified using the SMIS.

Perineal body length as a risk factor for ultrasound-diagnosed anal sphincter tear at first delivery

Shortened perineal body (PB) is associated with an increased risk of ultrasound-detected obstetric anal sphincter tear. The objective was to determine if shortened perineal body length (<3 cm) is a risk factor for ultrasound-detected anal sphincter tear at first delivery. Pregnant nulliparous women were recruited over 18 months. At 35-37 weeks' gestation and 6 weeks' postpartum perineal body length (PB) was measured and subjects completed quality of life questionnaires. Primary outcome was ultrasound-diagnosed anal sphincter tear at 6 weeks postpartum. Secondary outcomes were also assessed. A priori power analysis determined that 70 subjects were needed to detect a difference in anal sphincter tear based on a PB cut-off of 3 cm. Seventy-three subjects completed the study. Mode of delivery was 69.9% spontaneous vaginal, 15.1% operative vaginal, and 15.1% labored cesarean. There were 25 anal sphincter abnormalities (34.2%) seen on ultrasound: 11 (15.1%) internal or external sphincter tears, 3 (4.1%) internal sphincter atrophy, 6 (8.2%) external sphincter thinning, and 7 (9.6%) external sphincter scarring. Only the 11 sphincter tears qualified as abnormal for the primary outcome. In the vaginal delivery group 16.4% (10 out of 61) had a sphincter tear, compared with 8.3% (1 out of 12) in the labored cesarean group (p = 0.68). Women with PB < 3 had a significantly higher rate of ultrasound-diagnosed anal sphincter tear (40.0% vs 11.1%, p = 0.038). When comparing women with and without sphincter tear, there was a significant difference in mean antepartum PB (3.1 vs 3.7 cm, p = 0.043). A shortened perineal body length in primiparous women is associated with an increased risk of anal sphincter tear at the time of first delivery.

The impact of an intervention programme employing a hands-on technique to reduce the incidence of anal sphincter tears: interrupted time-series reanalysis

ObjectiveTo re-evaluate previously published findings from an uncontrolled before–after evaluation of an intervention programme to reduce the incidence of anal sphincter tears. A key component of the programme was the...

Complete Obstetric Anal Sphincter Tear and Risk of Long-term Fecal Incontinence

Women with anal sphincter injuries have an increased risk of developing fecal incontinence despite surgical intervention. The aim of this study was to evaluate the long-term risk of fecal incontinence after primary anal sphincter reconstruction and its impact on quality of life. This was a cohort study. This study was performed at Aarhus University Hospital. Women with complete anal sphincter rupture (exposed) from 1976 to 1991 and a control group of parous women (nonexposed) were included. The primary outcomes measured were fecal incontinence, Wexner score, St Mark incontinence score, and quality of life. A total of 363 women were included (125 exposed and 238 nonexposed). The mean age was 50.4 years (95%CI: 49.8-51.0), with 22.2 years (95% CI: 21.7-22.6) of follow-up. At the time of follow-up, 49% of exposed women and 74% of nonexposed women were continent. Complete anal sphincter tear increases the risk of fecal incontinence twofold (relative risk = 2.00; 95%CI: 1.52-2.63). No other risk factors were identified. The mean Wexner score was 1.7 (95%CI: 1.3-2.1) vs 1.1 (95%CI: 0.7-1.4) (p = 0.02), and the mean St Mark score was 2.8 (95% CI: 2.1-3.4) vs 1.4 (95%CI: 1.0-1.9) (p < 0.001) in the exposed and nonexposed groups. Severity of fecal incontinence had a significant impact on the quality of life independent of exposure. The cohort is relatively young; a short postmenopausal period limits the assessment of hormonal status and the effect of postmenopausal hormone replacement therapy. Complete obstetric anal sphincter tear increases the long-term risk of fecal incontinence twofold. When present, the severity of the incontinence symptoms is minor and the risk of incontinence for solid stool is not increased in comparison with the general population. Anal sphincter rupture is the only independent risk factor for fecal incontinence. The severity of fecal incontinence had the same impact on quality of life in both groups.

Overlapping Compared With End-to-End Repair of Complete Third-Degree or Fourth-Degree Obstetric Tears

Traditional obstetric practice for repair of third-degree or fourth-degree tears of the external anal sphincter has been using an end-to-end technique. Studies reporting that end-to-end repair was associated with higher rates of external anal sphincter defects and associated anal incontinence symptoms led to increased preference by clinicians for performing overlapping repair of obstetric anal sphincter lacerations. This study reports the results of a 3-year follow-up of a randomized controlled trial conducted in women who underwent primary repair of a complete third-degree or fourth-degree obstetric tear with either the overlapping technique or the end-to-end procedure. Participants were primiparous women enrolled at a single tertiary-care academic center between 2001 and 2007. Eligible women were randomized to receive either end-to-end (n = 86) or overlapping (n = 88) external anal sphincter repair. At a follow-up of 1, 2, and 3 years, questionnaires were mailed to participants to determine rates of flatal and fecal incontinence. At 1 year, rates of flatal and fecal incontinence were lower in women who underwent an end-to-end repair than in those who had an overlapping repair. The flatal incontinence rate was 31% for end-to-end repair and 56% for overlapping repair (difference: 25%, with a 95% confidence interval of 6%–43%; P = 0.012). The fecal incontinence rate for end-to-end repair was 7% and for overlapping repair was 16% (difference: 9%, with a 95% confidence interval of −4% to 21%; P = 0.17). By the end of year 2, the difference between the 2 methods of surgical repair had largely disappeared. These findings indicate that at 1-year follow-up, end-to-end repair of complete third-degree or fourth-degree obstetric anal sphincter tears is less likely than overlapping repair to result in anal incontinence. The lower rate of anal incontinence with end-to-end repair is not sustained at 2 years, suggesting no long-term benefit of either technique over the other.

Overlapping Compared With End-to-End Repair of Complete Third-Degree or Fourth-Degree Obstetric Tears

To report on a 3-year follow-up of women who underwent overlapping repair of a complete third-degree or fourth-degree obstetric tear. Primiparous women sustaining a complete third-degree or a fourth-degree tear of the perineum were randomized to a primary sphincter repair using either an end-to-end or an overlapping surgical technique. At 1, 2, and 3 years, questionnaires on rates of flatal and fecal incontinence were mailed to participants. At 1 year, women who underwent an end-to-end repair reported lower rates of flatal and fecal incontinence than women who had an overlapping repair. For flatal incontinence the rates were 31% compared with 56% (95% confidence interval for the rate difference 6-43%, P=.012). For fecal incontinence, the rates were 7% compared with 16% (95% confidence interval for the rate difference -4% to 21%, P=.17). The difference between the two methods of surgical repair had largely disappeared by the end of year 2. At 1-year follow-up, end-to-end repair of complete third-degree or fourth-degree obstetric anal sphincter tears is associated with significantly lower rates of anal incontinence when compared with overlapping repair. There is no long-term benefit associated with either technique over the other. ISRCTN Register, http://isrctn.org, ISRCTNO 4149919. I.

Incontinence after primary repair of obstetric anal sphincter tears is related to relative length of reconstructed external sphincter: a case–control study

To determine if anatomic primary repair with end-to-end reconstruction of the external anal sphincter (EAS) in its full length combined with separate repair of coexisting internal anal sphincter (IAS) tear, when present, results in less incontinence and better anal sphincter integrity compared with conventional primary end-to-end repair in which the IAS is not actively reconstructed. Women who sustained third- or fourth-degree obstetric tears were included prospectively in the study following anatomic primary repair. Women treated with conventional primary repair prior to the study period comprised the control group. Three-dimensional endoanal ultrasonography (3D-EAUS) images were classified according to the EAUS defect score, and incontinence according to St Mark's score. Sixty-three women were included in the study group and 61 in the control group, with mean follow-up times of 11 and 21 months, respectively. Among women who had not delivered vaginally prior to the tear, St Mark's score ≥ 3 was reported by 9.6% (5/52) in the study group and 37.5% (15/40) in the control group at follow-up (P = 0.002). The corresponding numbers among women who had previously delivered vaginally were 36.4% (4/11) and 42.9% (9/21), respectively (non-significant). St Mark's score correlated with the EAUS defect score (P = 0.017). An EAS defect exceeding 50% of the sphincter length was significantly less common in the study group, and in a multivariable logistic regression model, mode of repair (anatomic vs conventional) was the only factor explaining the difference in EAS sphincter length between the two groups (P = 0.007). Improved continence status after anatomic primary repair was associated with a better longitudinal reconstruction of the EAS, while the integrity of the IAS did not differ between the groups. Women with a history of vaginal delivery prior to the sphincter tear had an inferior outcome regardless of mode of repair.

Re: Incontinence after primary repair of obstetric anal sphincter tears is related to relative length of reconstructed external sphincter: a case–control study. S. Norderval, K. Røssaak, A. Markskog and B. Vonen. Ultrasound Obstet Gynecol 2012; 40: 207–214.

Interest in the diagnosis and appropriate repair of obstetric anal sphincter injuries (OASIS) has been rekindled in the last two decades by the advent of endoanal endosonography. However, many issues remain to be resolved. The authors of this manuscript deserve commendation as they have now added another spoke to this ever-turning wheel. The external anal sphincter (EAS) is a striated muscle and damage to this muscle is usually associated with urgency and urge fecal incontinence. The internal anal sphincter (IAS) is a smooth muscle that maintains most of the resting tone and is responsible for ‘fine tuning’; its function is largely to control flatus and prevent passive soiling. Both these muscles work in concert to orchestrate the mechanism of maintaining anal continence. In their paper, Norderval et al. aimed to determine whether a better outcome could be obtained when a full-length repair of the EAS was achieved combined with separate repair of the torn IAS. Ideally, a randomized controlled study would have provided the best evidence, but it would be ethically difficult to justify not repairing a disrupted ring of functional IAS. Instead, they compared the outcome to that in a control group from some years earlier when the IAS was not routinely reconstructed as a separate entity. They found that improved continence status was associated with better longitudinal reconstruction of the EAS. This is an important finding, as it has previously been shown in patients with fecal incontinence who have undergone a secondary sphincter repair that the single independent predictor for subsequent continence was restoration of anal sphincter length1. A full-length primary repair is indeed achievable as the EAS has a well-defined proximal border. Indeed, Norderval et al. have shown in a previous study that shorter anal length following primary anal sphincter repair is associated with poorer outcome2. In contrast to the EAS, the IAS is a continuation of the circular muscle of the rectum, which becomes thickened distally to form the IAS. Its proximal margins are less well defined. In general, as the IAS is enveloped by the EAS, the EAS would have to be disrupted first before the IAS can tear, except proximally as the EAS is shorter in its anterior aspect. However, although this phenomenon has been demonstrated using endoanal ultrasound, it is not a common finding and isolated partial length IAS damage appears to have no physiological or clinical significance. The use of a validated endoanal ultrasound scoring system has ensured standardized reporting. As not all anal sphincter defects are associated with functional compromise, it may have been useful for Norderval et al. to perform anal manometry (measuring anal length and resting and squeeze pressures) to complement the ultrasound findings. The authors did not find a difference in size or length of IAS defects between the groups. While this finding could have been different with larger numbers, it could also reflect obstetricians' lack of familiarity with the IAS, although its identification and separate repair was described over a decade ago3. Consequently, the full extent of the IAS tear may not be identified and repaired. This highlights a very important issue, as the best, and possibly only, opportunity to repair a freshly torn IAS is by an obstetrician following delivery. Once fibrosis has occurred, colorectal surgeons find it very difficult to repair the IAS defect and therefore most colorectal surgeons simply divide and overlap the fibrosed anterior sphincter bulk of tissue. In their study, women with a prior vaginal delivery had an inferior outcome regardless of the mode of repair. One explanation given is that OASIS may have been undiagnosed after the first vaginal delivery. This is very plausible, as it has been shown that a considerable number of anal sphincter tears are not diagnosed at delivery and focused training can improve the diagnostic yield4. However, as over 80% of anal sphincter tears occur with the first vaginal delivery, the incidence of such injuries in multiparous women should be low. Finally, the authors should be excused for being unable to reach the intended number of women in this study. The reason for this was that the number of women sustaining OASIS was dramatically reduced following an intervention program that was implemented in four different units in Norway5. Over the last two decades we have come a long way. Using endoanal endosonography we established that OASIS were being missed because clinical training was suboptimal. Studies conducted by Norderval and others have explored better surgical techniques. The time has now come to focus on preventative strategies and implement training sessions like the Norwegian intervention program at a global level. Only then can we minimize the occurrence of OASIS with its attendant morbidity on women's quality of life. A. H. Sultan*, * Department of Obstetrics and Gynaecology, Croydon University Hospital, London Road, Croydon CR7 7YE, Surrey, UK

Impact of liberal use of mediolateral episiotomy on the incidence of obstetric anal sphincter tear

To assess the impact of liberal compared with restrictive use of mediolateral episiotomy on the incidence of obstetric anal sphincter tear (OAST). Data between the years 1999-2001 (era 1) when liberal mediolateral episiotomy was applied were compared with the years 2004-2008 (era 2) when restricted mediolateral episiotomy was implemented. Liberal mediolateral episiotomy was done for fetal or maternal indications, while restrictive mediolateral episiotomy was done when a tear was imminent. Primary outcome was the incidence of OAST. A total of 25,170 women who delivered vaginally were included. After adjusting for potential confounders, the incidence of OAST was found to be significantly higher in era 2 (0.4%) compared to era 1 (0.1%), (p=0.02; adjusted OR 2.23; 95% CI, 1.16-4.29). Among primiparous women, the incidence of mediolateral episiotomy was 71.8 and 27.1% in eras 1 and 2, respectively (p<0.001), and the incidence of OAST was 0.2 and 1% in eras 1 and 2, respectively (p=0.009; adjusted OR 4.15; 95% CI, 1.42-12.10). Among multiparous women, the incidence of OAST did not differ significantly (p=0.52). Returning to the liberal policy among primiparous women only, 124 deliveries are needed to prevent one OAST. Liberal compared to restrictive use of mediolateral episiotomy may be a sphincter-saving procedure among primiparous women.

Overlapping compared with end-to-end repair of third and fourth degree obstetric anal sphincter tears

There is a significant risk of anal incontinence in women who sustain a third or fourth degree tear of the external anal sphincter (EAS) at the time of delivery. Optimizing the surgical correction of these injuries should result in the best functional outcome for women. The purpose of this review is to examine recent evidence. The results of randomized trials are conflicting. Four trials have found no difference between the overlapping and end-to-end repairs. One trial found the overlapping procedure superior and one found the end-to-end procedure to be superior. Repair of the internal anal sphincter is an important part of the surgical repair. Surgeon experience with specific surgical procedures does not significantly affect outcomes. Methodological limitations have compromised the conclusions of the majority of the studies and longer-term follow-up is still needed. At present, the bulk of the evidence (follow-up to 12 months) finds that there is no difference in symptomatic outcomes between the end-to-end or the overlapping repair of EAS defects. A surgeon should use the technique with which they are most familiar. Obstetricians should familiarize themselves with the most up-to-date evidence concerning the anatomy of the EAS and take care to identify and repair both the internal anal sphincter and EAS at the time of an obstetrical injury. Surgeon experience with specific repair procedures does not affect outcomes of EAS defect repair.

Overlapping Compared With End-to-End Repair of Third- and Fourth-Degree Obstetric Anal Sphincter Tears: A Randomized Controlled Trial

Overlapping Compared With End-to-End Repair of Third- and Fourth-Degree Obstetric Anal Sphincter Tears: A Randomized Controlled Trial