Objective: To determine the prevalence of obstetric anal sphincter injuries (OASIS) in a cohort of primiparous women and to evaluate their association with demographic, obstetric and ultrasound parameters.Methods: This was a retrospective analysis of the ultrasound volume datasets of 320 primiparous women, acquired at 5 months postpartum. Tomographic ultrasound imaging (TUI) was used to evaluate the external anal sphincter (EAS). A significant EAS defect was diagnosed if a defect of > 30° was seen in four or more of six TUI slices bracketing the EAS.Results: Significant EAS defects were found in 69 women (27.9% of those delivered vaginally). In nine of those a third‐degree tear was diagnosed intrapartum and was sutured. In 60 women with significant defects there was no documentation of sphincter damage at birth, implying unidentified or occult defects (60/69, 87.0%). Among them, 29 had had a second‐degree tear, two a first‐degree tear and three an intact perineum. In 31 cases an episiotomy had been performed, with five extensions to a third‐degree tear. On multivariate analysis only forceps delivery was significantly associated with OASIS.Conclusions: In this cohort of primiparous women we found OASIS in 27.9% of vaginally parous women, most of which had not been diagnosed in the delivery suite. There seems to be a need for better education of labor‐ward staff in the recognition of OASIS. On the other hand, it is conceivable that some defects may be masked by intact tissue. The significance of such defects remains doubtful. Forceps delivery was the only identifiable risk factor. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.

Objectives To determine the prevalence of evidence of residual obstetric anal sphincter injury, to evaluate its association with anal incontinence (AI) and to establish minimal diagnostic criteria for significant (residual) external anal sphincter (EAS) trauma. Methods This was a retrospective analysis of ultrasound volume datasets of 501 patients attending a tertiary urogynecological unit. All patients underwent a standardized interview including determination of St Mark's score for those presenting with AI. Tomographic ultrasound imaging (TUI) was used to evaluate the EAS and the internal anal sphincter (IAS). Results Among a total of 501 women, significant EAS and IAS defects were found in 88 and 59, respectively, and AI was reported by 69 (14%). Optimal prediction of AI was achieved using a model that included four abnormal slices of the EAS on TUI. IAS defects were found to be less likely to be associated with AI. In a multivariable model controlling for age and IAS trauma, the presence of at least four abnormal slices gave an 18-fold (95% CI, 9–36; P < 0.0001) increase in the likelihood of AI, compared with those with fewer than four abnormal slices. Using receiver–operating characteristics curve statistics, this model yielded an area under the curve of 0.86 (95% CI, 0.80–0.92). Conclusions Both AI and significant EAS trauma are common in patients attending urogynecological units, and are strongly associated with each other. Abnormalities of the IAS seem to be less important in predicting AI. Our data support the practice of using, as a minimal criterion, defects present in four of the six slices on TUI for the diagnosis of significant EAS trauma. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Objectives 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. Methods 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. Results 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. Conclusions 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. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

Objectives: Levator avulsion has been shown to be associated with anterior and central compartment prolapse and is a risk factor for prolapse recurrence. Diagnosis in the delivery room is usually impossible, as levator avulsion is commonly occult. The objective of this study was to determine if vaginal and major perineal tears are clinical markers of levator trauma as diagnosed by four‐dimensional (4D) translabial ultrasound 3–6 months postpartum.Methods: This was a retrospective observational study using data obtained in two perinatal trials. A total of 774 women seen, on average, 5 (range, 2.3–22.4) months after their first delivery of a term singleton cephalic baby underwent a standardized interview, clinical assessment and 4D translabial ultrasound examination. Clinical data were obtained from the institutional obstetric database, including information on vaginal and perineal tears. Levator avulsion was diagnosed using tomographic ultrasound, with operators blinded to the clinical data.Results: Both third‐ and fourth‐degree perineal tears and vaginal sidewall tears were independently associated with levator avulsion (P = 0.004 and P = 0.012, respectively). The odds ratio for avulsion in women suffering from such overt trauma was 3.44 (95% CI, 1.47–8.03) for third‐/fourth‐degree perineal tears and 3.35 (95% CI, 1.30–8.61) for vaginal sidewall tears.Conclusions: Vaginal sidewall and third‐/fourth‐degree perineal tears were found to be independent clinical indicators of an increased risk of levator trauma, as diagnosed by 4D translabial ultrasound 3–6 months postpartum. Such clinical markers may become useful in the identification of women at high risk of levator trauma and future pelvic floor disorders. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.