Mode of delivery after obstetric anal sphincter injury

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.

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.

Follow up of women after obstetric anal sphincter injuries (OASI)-What is the role of anorectal testing?

AIMS

To evaluate the benefit of performing anorectal studies on all women following primary obstetric anal sphincter injury (OASI) repair over performing them on symptomatic women only.

METHODS

Women who attended perineal clinic between 2007 and 2020 underwent symptom assessment and anorectal studies at 6 weeks and 6 months postpartum. Anorectal studies including endo anal ultrasound (EAUS) and anal manometry (AM) were performed. The anorectal studies of symptomatic women who were the case group, were compared with asymptomatic women who were the control group.

RESULTS

A total of 1348 women were seen in the perineal clinic over 13 years. A total of 454 (33.7%) women were symptomatic. A total of 894 (66.3%) women were asymptomatic. A total of 313 (35%) asymptomatic women had two abnormal anorectal studies, 274 (31%) had abnormal AM alone, and 86 (9.6%) had abnormal EAUS alone. A total of 221 (24.7%) asymptomatic women had normal anorectal studies.

CONCLUSION

Almost 70% of women were asymptomatic 6 months following primary OASI repair. Most had at least one abnormal anorectal study result. Selectively performing anorectal tests on symptomatic women would not identify asymptomatic women at risk of future faecal incontinence following further vaginal birth. Without anorectal study results, women would not receive accurate counseling about the risks of vaginal birth. Anorectal studies should be offered to all women following OASI where resources allow.

The role of anal manometry in the follow-up of women with obstetric anal sphincter injuries (OASI)

INTRODUCTION AND HYPOTHESIS

Mode of birth (MOB) following OASI is determined by choice, symptoms and anorectal study results in asymptomatic women. Endoanal ultrasound (EAUS) is the gold-standard imaging modality. EAUS use in MOB counselling is supported by strong evidence. Less is understood about how anal manometry (AM) influences MOB counselling.

METHODS

A retrospective observational study was conducted from 2007 to 2020. Women underwent symptom assessment using validated ePAQ and St Mark's incontinence score (SMIS). Anorectal studies using EAUS and AM were performed. The case group was the normal ultrasound group and the control group was the abnormal ultrasound group. Both groups were compared with normal and abnormal AM result groups.

RESULTS

A total of 1348 women were included over 13 years. Among these, 454 women were symptomatic, 894 were asymptomatic; 274 (31%) asymptomatic women had isolated abnormal AM results, 313 (35%) had two abnormal anorectal results and 221 (24.7%) had normal anorectal results. Eighty-six asymptomatic women (10.4%) had isolated abnormal EAUS results, 138 (30.4%) symptomatic women had isolated abnormal AM, 221 (48.7%) had two abnormal anorectal results and 57 (12.6%) had normal anorectal results. Thirty-eight symptomatic women (8.4%) had an isolated abnormal EAUS result.

CONCLUSIONS

AM identifies more women with sphincter function impairment than EAUS alone. Without AM, almost one third of asymptomatic women would not have been identified and could have been inadequately counselled. Performing AM and EAUS together captured most women with compromised anal sphincter function. We conclude that AM should be performed in all women with OASI alongside EAUS to enable accurate MOB counselling.

Factors that influence pregnant women's decision on mode of delivery after previous obstetric anal sphincter injury

PURPOSE

Maternal request for caesarean section (CS) is increasing. One common reason is following a previous obstetric anal sphincter injury (OASI). We aim to understand which factors bear the greatest influence in driving this women's decision-making process once they are pregnant after having sustained an OASI.

METHODS

Pregnant women with a previous OASIS who were attending their first antenatal appointment were deemed eligible and were asked to complete two questionnaires on their preferred mode of delivery (MoD) and ongoing pelvic floor symptomatology. Data were analysed with descriptive and inferential statistics using SPSS, and results were presented both quanti- and qualitatively.

RESULTS

Data from 63 participants was included in the final analysis. Most women had experienced 3A/3B OASIS (n = 49, 77.78 %), and they were more likely to report bladder pain and difficulties with voiding than those with major tears (p < 0.05). The type of tear did not impact directly on the preferred MoD. However, women still experiencing bladder pain were more likely to request a CS (p < 0.05). Even though all participants who attended a perineal trauma clinic postpartum found it helpful, they reported that ultimately the decision on how to deliver was theirs, and their ideas and concerns played the greatest influence.

CONCLUSION

Pregnant women with ongoing urinary symptoms rather than sexual or bowel dysfunction seem to favour a planned CS, regardless of the severity of their previous tear. Postpartum follow-up in a perineal trauma clinic is extremely valuable but even more is the need to understand women's motivations to support them make an informed decision.

Establishing a peripartum perineal trauma clinic: a narrative review

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injury (OASI) is not rare, and its consequences are multiple and potentially severe, especially for young women. Some dedicated perineal clinics have been established to improve the management of OASI. Despite their obvious importance, these specific clinics are underrepresented and underdeveloped. The objectives of this review are to explore various options for developing a peripartum perineal clinic and to compare the different practices regarding the mode of delivery for subsequent pregnancies after an OASI.

METHODS

This narrative review covers information from patients' questionnaires specific to anal incontinence, anal physiology assessment, pelvic floor and anal sphincter imaging, and the arguments for choosing the mode of delivery after an OASI.

RESULTS

This review highlights the extensive range of practices regarding the delivery mode after an OASI throughout national professional organizations and experienced perineal clinics.

CONCLUSION

This review summarizes the different choices in developing a perineal clinic to facilitate their development in promoting health care and education specific for peripartum women concerning the perineal consequences of delivery for obstetrician-gynaecologists, family doctors, and residents.

Effect of a subsequent pregnancy on anal sphincter integrity and function after obstetric anal sphincter injury (OASI)

Introduction and hypothesis

Endoanal ultrasound (EAUS) and anal manometry are used in the assessment women with a history of obstetric anal sphincter injury (OASI), both postpartum and in a subsequent pregnancy, to aid counselling regarding mode of delivery (MOD).

Methods

A prospective observational study between 2012 to 2020 was completed. Women were reviewed 3 months postpartum following OASI and in the second half of a subsequent pregnancy. Anorectal symptoms were measured using the validated St Mark’s Incontinence Score (SMIS: asymptomatic to mild symptoms = ≤ 4). Anal manometry (incremental maximum squeeze pressure [iMSP: normal = > 20 mmHg]) and EAUS (abnormal = sphincter defect > 1 h in size) were performed.

Results

One hundred forty-six women were identified and 67.8% had an anal sphincter defect ≤ 1 h in size postnatally. In those with a defect ≤ 1 h, postpartum mean iMSP and SMIS significantly improved in a subsequent pregnancy (p = 0.04 and p = 0.01, respectively). In women with a defect > 1 h, there was no significant difference between the mean iMSP or SMIS score postnatally compared to a subsequent pregnancy. At both time points, significantly more women had an anal sphincter defect ≤ 1 h and SMIS of ≤ 4 (p = 0.001 and p < 0.001 respectively) compared to those with a defect < 1 h. In addition, significantly more women had an anal sphincter defect ≤ 1 h and iMSP ≥ 20 mmHg (p < 0.001). Overall, out of the 146 women included in this study, 76 (52.1%) with a defect ≤ 1 h also had an iMSP ≥ 20 mmHg and SMIS ≤ 4 at 3 months postpartum.

Conclusions

Women who remain asymptomatic with normal anal manometry and no abnormal sphincter defects on EAUS postnatally do not need to have these investigations repeated in a subsequent pregnancy and can be recommended to have a vaginal delivery. If our protocol was modified, over half of the women in this study could have had their MOD recommendation made in the postnatal period alone.

A one-stop perineal clinic: our eleven-year experience

Introduction and hypothesis

The perineal clinic is a dedicated setting offering assessment for various childbirth-related presentations including obstetric anal sphincter injuries (OASIs), perineal wound complications, pelvic floor dysfunction and other conditions such as female genital mutilation(FGM). We describe the clinical presentation and outcomes of women from a tertiary perineal clinic based on data collected over an 11-year period.

Methods

This is a retrospective observational study. A one-stop outpatient service was offered to all women who sustained OASIs (postnatally and antenatally in a subsequent pregnancy), perineal complications (within 16 weeks postpartum), FGM and/or peripartum symptoms of urinary/anal incontinence or prolapse. Assessment included history with validated questionnaires, examination and anal manometry and endoanal ultrasound when appropriate. Outcomes were compared among different grades of OASIs. Management of each type of presentation was reported with outcomes.

Results

There were 3254 first attendance episodes between 2006 and 2016. The majority (58.1%) were for OASIs, followed by perineal wound complications. Compared to the lower grades, the higher grades of OASI were associated with poorer outcomes in terms of symptoms, investigations and complications. Women with OASIs had unrelated symptoms such as urinary incontinence, perineal pain and wound infections that needed further intervention. A high proportion(42%) of wound complications required further specialist management.

Conclusion

We describe a dedicated, one-stop perineal clinic model for antenatal and postnatal women for management of perineal and pelvic floor disorders. This comprehensive and novel data will enable clinicians to better counsel women regarding of outcomes after OASI and focus training to minimize risks of morbidities.

Management of subsequent pregnancies following fourth-degree obstetric anal sphincter injuries (OASIS)

OBJECTIVES

The management of subsequent pregnancy in women who sustained OASIS remains an enigma. Nearly all studies include all grades of OASIS including fourth-degree tears. In addition, most protocols require endoanal ultrasound and anal manometric assessment to provide advice regarding mode of delivery. In reality, most women who sustain an OASI do not undergo these investigations. The aims of our study were firstly to evaluate outcomes of fourth-degree OASIS in terms of sphincter defects, anal manometry and anal incontinence symptoms. Secondly, we wished to review recommendations made regarding subsequent mode of delivery after fourth-degree OASIS according to different published protocols.

STUDY DESIGN

An observational study of all women who had undergone a primary repair of a fourth-degree tear and seen in the perineal clinic of a tertiary urogynaecology unit between January 2006 and December 2017. Three-dimensional endoanal ultrasound and anal manometry were performed on all women, and symptoms assessed using the validated modified St Mark's Score for anal incontinence. Diagnostic test accuracy analysis was performed for use of symptoms in predicting abnormal investigations.

RESULTS

74 fourth-degree tears were identified (mean follow-up 5.9 months; SD 11.5). Endoanal scan showed an internal anal sphincter defect in 77 % and an external anal sphincter defect in 49 %. Only 18 % had no defect. The mean incremental pressure rise was 12.6 mmHg (SD 15.5). 61 % were asymptomatic with a mean St Mark's Score of 3.8 (SD 5.4). The presence of symptoms alone had poor accuracy in predicting abnormal investigations. Based on Royal College of Obstetricians and Gynaecologists guidance, only 7% would not be offered a caesarean section as they are asymptomatic women with normal scan and manometry findings and would be counselled for a vaginal delivery.

CONCLUSIONS

Given that only a few units offer these specialist investigations to their OASI population, it would be reasonable to offer caesarean section to all women who have sustained a fourth-degree tear. However, in centres where endoanal ultrasound and anal manometry are available, individualised counselling can be offered.

Is endoanal, introital or transperineal ultrasound diagnosis of sphincter defects more strongly associated with anal incontinence?

INTRODUCTION AND HYPOTHESIS

Our aim was to explore the association between anal incontinence (AI) and persistent anal sphincter defects diagnosed with 3D endoanal (EAUS), introital (IUS) and transperineal ultrasound (TPUS) in women after obstetric anal sphincter injury (OASI) and study the association between sphincter defects and anal pressure.

METHODS

We carried out a cross-sectional study of 250 women with OASI recruited during the period 2013-2015. They were examined 6-12 weeks postpartum or in a subsequent pregnancy with 3D EAUS, IUS and TPUS and measurement of anal pressure. Prevalence of urgency/solid/liquid AI or flatal AI and anal pressure were compared in women with a defect and those with an intact sphincter (diagnosed off-line) using Chi-squared and Mann-Whitney U test.

RESULTS

At a mean of 23.6 (SD 30.1) months after OASI, more women with defect than those with intact sphincters on EAUS had AI; urgency/solid/liquid AI vs external defect: 36% vs 13% and flatal AI vs internal defect: 27% vs 13%, p < 0.05. On TPUS, more women with defect sphincters had flatal AI: 32% vs 13%, p = 0.03. No difference was found on IUS. Difference between defect and intact sphincters on EAUS, IUS and TPUS respectively was found for mean [SD] maximum anal resting pressure (48 [13] vs 55 [14] mmHg; 48 [12] vs 56 [13] mmHg; 50 [13] vs 54 [14] mmHg) and squeeze incremental pressure (33 [17] vs 49 [28] mmHg; 37 [23] vs 50 [28] mmHg; 36 [18] vs 50 [30] mmHg; p < 0.01).

CONCLUSIONS

Endoanal ultrasound had the strongest association with AI symptoms 2 years after OASI. Sphincter defects detected using all ultrasound methods were associated with lower anal pressure.

Parturition mode recommendation and symptoms of pelvic floor disorders after obstetric anal sphincter injuries

INTRODUCTION AND HYPOTHESIS

Our primary objective was to evaluate parturition mode (PM) recommendations following obstetric anal sphincter injuries (OASIs) and adherence to these recommendations and to evaluate recurrence of OASIs in women who had a subsequent vaginal delivery (VD). The hypothesis was that adherence to the PM recommendations leads to a reasonable OASI recurrence rate.

METHODS

This was a retrospective observational cohort study of patients with previous OASIs between 2010 and 2016. After an outpatient visit including 3D transperineal ultrasound to screen for pelvic floor and anal sphincter injuries, all patients received recommendations for a subsequent PM. Patients were invited to complete validated questionnaires 2 to 5 years post-OASIs.

RESULTS

The majority of invited patients (265/320) attended follow-up, with 264 receiving a recommendation for PM. Only 5.6% did not adhere to the received recommendation. One hundred sixty-one patients delivered again, 58% had a VD, and 42% had a cesarean section (CS). Recurrence of OASIs was observed in 4.3% of the patients that had a VD. Fecal incontinence occurred in 4.9%, however any form of anal incontinence in 48% of patients. While dyspareunia was common in patients with residual external anal sphincter (EAS) injuries and levator ani muscle (LAM) avulsions, anal pain occurred more frequently in EAS injuries and fecal incontinence in LAM avulsions.

CONCLUSIONS

This study showed that the vast majority of patients followed PM recommendations, and this resulted in a low recurrence of OASIs with a high CS rate. Fecal incontinence after OASIs was correlated with the degree of OASIs.

[Cesarean section and perineal protection: CNGOF Perineal Prevention and Protection in Obstetrics Guidelines]

OBJECTIVE

The endpoint was to assess the interest of planned cesarean section in primary and secondary obstetrical perineal prevention.

METHODS

This is a review of the literature about the impact of the mode of delivery in urinary incontinence (UI), anal incontinence (AI), pelvic organ prolapse (POP), sexual disorders de novo or prior to delivery and history of obstetric anal sphincter injuries (OASI).

RESULTS

The studies about UI, AI and sexual disorders report a potential protective impact of cesarean section but with a possible selection bias and an inadequate comparability of the groups. Randomized trials do not report any protective effect of planned cesarean section for these 3 disorders. The literature about POP reports a higher risk for the women who delivered vaginally but still with a possible selection bias et there is no randomized trial for this outcome. About the secondary prevention of OASI, there is no evidence in the literature for a benefit of a systematic planned cesarean section for all women. For symptomatic women, the mode of delivery has to be discussed individually. In secondary prevention of UI, AI, POP and sexual disorders, there is no evidence in the literature for a benefit of planned cesarean section even if there is a history of surgical procedure for the disorder.

CONCLUSION

Planned cesarean section is not recommended in order to prevent primary or secondary obstetrical perineal disorders except for symptomatic OASI for whom an individual discussion about the mode of delivery is recommended.

Mode of delivery following an OASIS and caesarean section rates

OBJECTIVES

While the rate of obstetric anal sphincter injury (OASIS) is increasing, there is a lack of evidence on how best to advise women on mode of delivery (MOD) afterwards. The objectives of this study were to assess the clinical value of bowel symptoms, endoanal ultrasound and anorectal manometry in the management of pregnancies after an OASIS and evaluate the performance of different algorithms.

STUDY DESIGN

This was a retrospective analysis of prospectively collected data in a university hospital perineal clinic. Women with OASIS undergoing endoanal ultrasound scan (EAUS) and anorectal manometry (AM) were included in this study (all women with an OASIS, except the asymptomatic 3a tears). A number of published algorithms were theoretically applied in this cohort to define recommended MOD after an OASIS.

RESULTS

Out of the 233 women included in the study, 51 (21.9%) were symptomatic, 141 (60.5%) had persistent sphincter defects on EAUS and 124 (53.2%) had abnormal AM. One asymptomatic and five symptomatic women were found to have isolated internal anal sphincter (IAS) defects without external anal sphincter (EAS) defects. There were no women with low resting pressure and normal incremental squeeze pressure. The application of the algorithm requiring only one abnormal investigation to be recommended caesarean would have led to an 81.5% caesarean rate. If women with symptoms of anal incontinence or abnormal investigations would be advised for caesarean the rate would be 85.0%. Using the local protocol where symptomatic women only needed one of the two investigations to be abnormal but asymptomatic women were required to have both investigations being abnormal, 94 were considered for caesarean (40.3%).

CONCLUSION

There is a wide range in the number of patients recommended to have caesarean section after an OASIS, depending on the used criteria and management algorithms. There is minimal additional information gained from identifying internal anal sphincter defects and measuring low resting pressures at manometry.

Expert consensus document: Advances in the evaluation of anorectal function

Faecal incontinence and evacuation disorders are common, impair quality of life and incur substantial economic costs worldwide. As symptoms alone are poor predictors of underlying pathophysiology and aetiology, diagnostic tests of anorectal function could facilitate patient management in those cases that are refractory to conservative therapies. In the past decade, several major technological advances have improved our understanding of anorectal structure, coordination and sensorimotor function. This Consensus Statement provides the reader with an appraisal of the current indications, study performance characteristics, clinical utility, strengths and limitations of the most widely available tests of anorectal structure (ultrasonography and MRI) and function (anorectal manometry, neurophysiological investigations, rectal distension techniques and tests of evacuation, including defecography). Additionally, this article provides our consensus on the clinical relevance of these tests.

Effect of subsequent vaginal delivery on bowel symptoms and anorectal function in women who sustained a previous obstetric anal sphincter injury

Introduction and hypothesis

Our primary objective was to prospectively evaluate anorectal symptoms, anal manometry and endoanal ultrasound (EAUS) in women who followed the recommended mode of subsequent delivery following index obstetric anal sphincter injuries (OASIs) using our unit’s standardised protocol. Our secondary objectives were to evaluate the role of internal anal sphincter defects and also to compare outcomes in a subgroup of symptomatic women with normal anorectal physiology.

Methods

This is a prospective follow-up study of pregnant women with previous OASIs who were counselled regarding subsequent mode of delivery between January 2003 and December 2014. Assessment involved the St Mark’s Incontinence Score (SMIS), anal manometry and EAUS at both antepartum and 3-month postpartum visits. Data were analysed using Wilcoxon and Mann–Whitney U tests.

Results

Three hundred and fifty women attended the perineal clinic over the study period, of whom 122 met the inclusion criteria (99 vaginal delivery [VD], 23 caesarean section). No significant worsening of anorectal symptoms was observed following subsequent delivery in the VD group (p = 0.896), although a reduced squeeze pressure was observed at 3 months postpartum (p < 0.001). There were no new defects on EAUS in either group.

Conclusions

This study showed no significant worsening of bowel symptoms and sphincter integrity apart from lower squeeze pressures at 3 months postpartum in the VD group when our standardised protocol was used to recommend subsequent mode of delivery. In the absence of a randomised study, use of this protocol can aid clinicians in their decision-making.

Factors that influence patient preference for mode of delivery following an obstetric anal sphincter injury

PURPOSE

A common indication for elective caesarean is previous obstetric anal sphincter injury (OASI). This study aims to identify factors that influence womens' preferences regarding mode of delivery (MoD) in a subsequent pregnancy following an OASI.

METHODS

100 consecutive women who sustained an OASI completed a questionnaire when attending postnatal follow up at a perineal trauma clinic. They also completed ePAQ-PF to assess pelvic floor symptoms. Data was collated and percentages generated for each response. A chi-squared calculation was used for preferred MoD.

RESULTS

In total, 75 women were Primiparous and 25 Multiparous. 20% of women were advised to have a caesarean, with the remainder advised either a vaginal delivery or further investigations. 79% of women had a 3a/3b tear and 21% of women had a 3c/4th degree OASI. Based on women's preferences, those who sustained a 3c/4th degree tear were more likely to opt for CS than a 3a/b degree tear (p<0.001). Bowel symptoms per se did not correlate with choice of MoD in either group. In women with 3c/4th OASI vaginal or sexual symptoms did not impact on the decision regarding choice of delivery but in women who sustained a 3a/b tear the impact on sexual function appears to be the commonest symptom in those who wished a caesarean section.

CONCLUSION

Women with 3c/4th OASI are more likely to accept a planned CS. Bowel symptoms appear to have little impact on this but in women with lower grade tears sexual symptoms have the greatest impact on preferred MoD.

Overdiagnosis and rising rate of obstetric anal sphincter injuries (OASIS): time for reappraisal

OBJECTIVES

To determine the accuracy of clinical diagnosis of obstetric anal sphincter injuries (OASIS) using three-dimensional (3D) endoanal ultrasound (EA-US) and to compare symptoms and anal manometry measurements between women with anal sphincters adequately repaired and those with persistent anal sphincter defects.

METHODS

The EA-US images of women with clinically diagnosed and repaired OASIS, defined as third- or fourth-degree perineal tear, who attended the perineal clinic at Croydon University Hospital over a 10-year period (2003-2013) were reanalyzed by a single expert blind to symptoms and the results of clinical examination. St Mark's Incontinence Scores (SMIS) and anal manometry measurements were obtained and compared between women with an intact anal sphincter and those with an anal sphincter scar and between those with an intact anal sphincter and those with a defect. Anal manometry measurements were compared between women with an external anal sphincter (EAS) defect and those with an internal anal sphincter (IAS) defect.

RESULTS

The images of 908 women were reanalyzed. No evidence of OASIS was found in 64 (7.0%) women, an EAS scar alone was detected in 520 (57.3%) and an anal sphincter defect in 324 (35.7%). Of the 324 women with a defect, 112 had an EAS defect, 90 had an IAS defect and 122 had a combined IAS and EAS defect. SMIS results were significantly higher in women with an anal sphincter defect compared with those with no evidence of OASIS (P = 0.018), but there was no significant difference in scores between women with an intact sphincter and those with an EAS scar only. Women with a defect had a significantly lower maximum resting pressure (median (range), 44 (8-106) vs 55 (29-86) mmHg; P < 0.001) and maximum squeeze pressure (median (range), 74 (23-180) vs 103 (44-185) mmHg; P < 0.001) compared with those in the intact group. Similar, but less marked, differences were observed in women with an EAS scar compared with those who had an intact anal sphincter. The anal length was significantly shorter in women with a defect compared with those in the intact group (median (range), 20 (10-40) vs 25 (10-40) mm; P = 0.003).

CONCLUSIONS

Seven percent of women with a clinical diagnosis of OASIS were wrongly diagnosed. We believe that this rate may differ from that of other units but training methods and competency assessment tools for the diagnosis and repair of OASIS need urgent reappraisal. The role of EA-US in the immediate postpartum period needs further evaluation as the accurate interpretation of the images is dependent on the expertise of the staff involved. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.