Anal sphincter complex: 2D and 3D endoanal and translabial ultrasound measurement variation in normal postpartum measurements

Automatic anal sphincter integrity detection from ultrasound images via convolutional neural networks

BACKGROUND

The anal sphincter complex comprises the anal sphincter and the U-shaped deep and superficial puborectalis muscle. As an important supporting structure of the posterior pelvic floor, together with its surrounding tissues and muscles, the anal sphincter complex maintains the normal physiological functions of defecation and continence.

OBJECTIVE

The plane required for diagnosing anal sphincter injury and the diagnosis of anal sphincter integrity through pelvic floor ultrasound are highly dependent on sonographers' experience. We developed a deep learning (DL) tool for the automatic diagnosis of anal sphincter integrity via pelvic floor ultrasound.

METHODS

A 2D detection network was trained to detect the bounding box of the anal sphincter. The pelvic floor ultrasound image and its corresponding oval mask were input into a 2D classification network to determine the integrity of the anal sphincter. The average precision (AP) and intersection over union (IoU) were used to evaluate the performance of anal sphincter detection. Receiver operating characteristic (ROC) analysis was used to evaluate the performance of the classification model.

RESULTS

The Pearson correlation coefficients (r values) of the topmost and bottommost layers detected by the CNN and sonographers were 0.932 and 0.978, respectively. The best DL model yielded the highest area under the curve (AUC) of 0.808 (95% CI: 0.698-0.921) in the test cohort. The results from the CNN agreed well with the diagnostic results of experienced sonographers.

CONCLUSIONS

We proposed, for the first time, a CNN to obtain the plane required for diagnosing anal sphincter injury on the basis of pelvic floor ultrasound and for preliminarily diagnosing anal sphincter injury.

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.

Strategies to Distinguish Perianal Fistulas Related to Crohn's Disease From Cryptoglandular Disease: Systematic Review With Meta-Analysis

BACKGROUND

Management of perianal fistulas differs based on fistula type. We aimed to assess the ability of diagnostic strategies to differentiate between Crohn's disease (CD) and cryptoglandular disease (CGD) in patients with perianal fistulas.

METHODS

We performed a diagnostic accuracy systematic review and meta-analysis. A systematic search of electronic databases was performed from inception through February 2021 for studies assessing a diagnostic test's ability to distinguish fistula types. We calculated weighted summary estimates with 95% confidence intervals for sensitivity and specificity by bivariate analysis, using fixed effects models when data were available from 2 or more studies. The Quality Assessment of Diagnostic Accuracy Studies tool was used to assess study quality.

RESULTS

Twenty-one studies were identified and included clinical symptoms (2 studies; n=154), magnetic resonance imaging (MRI) characteristics (3 studies; n=296), ultrasound characteristics (7 studies; n=1003), video capsule endoscopy (2 studies; n=44), fecal calprotectin (1 study; n=56), and various biomarkers (8 studies; n=440). MRI and ultrasound characteristics had the most robust data. Rectal inflammation, multiple-branched fistula tracts, and abscesses on pelvic MRI and the Crohn's ultrasound fistula sign, fistula debris, and bifurcated fistulas on pelvic ultrasonography had high specificity (range, 80%-95% vs 89%-96%) but poor sensitivity (range, 17%-37% vs 31%-63%), respectively. Fourteen of 21 studies had risk of bias on at least 1 of the Quality Assessment of Diagnostic Accuracy Studies domains.

CONCLUSIONS

Limited high-quality evidence suggest that imaging characteristics may help discriminate CD from CGD in patients with perianal fistulas. Larger, prospective studies are needed to confirm these findings and to evaluate if combining multiple diagnostic tests can improve diagnostic sensitivity.

When to assess residual anal sphincter defect after OASI by ultrasound

OBJECTIVES

Obstetrical anal sphincter injuries (OASIS) are complications of vaginal delivery. Unrepaired anal sphincter after delivery increases the risk of anal incontinence. The aim of our study is to search for residual defect after OASI repair by 4D introital ultrasound (US). We hypothesised that imaging prior to hospital discharge would show the same number of defects as assessment at 3 months.

STUDY DESIGN

This is a retrospective analysis of 138 patients with immediate repair after OASIS. Since 2009, we have been routinely inviting all our patients with OASIS to the perineal clinic for postoperative follow-up. We scheduled the first visit before discharge from hospital and followed up with a second visit after three months. During both visits, patients underwent transperineal 4D ultrasound examination. We provided examination while at rest and during contraction; volumes were saved for further evaluation.

RESULTS

Eighty-one patients (58.7%) completed both exams and were included in the analysis. Residual external anal sphincter defect was found in 17.3% at the first visit versus 13.6% at the second (delayed) visit. We were not able to assess the sphincter in 9.9% at early versus none in the delayed examination. In 9.9%, the residual defect was not confirmed by the second examination, and in 4.9% the residual defect was missed by the first examination.

CONCLUSIONS

In conclusion, we have found that a 3 month scan yields a smaller number of defects than a scan before discharge.

The effect of vaginal delivery and Caesarean section on the anal Sphincter complex of Primipara based on optimized three-dimensional ultrasound image and nuclear regression Reconstruction Algorithm

Objective

The study used the optimized nuclear regression reconstruction algorithm to explore the value of three-dimensional perineal ultrasound evaluation of the effect of caesarean delivery and caesarean section on the anal sphincter complex of primipara.

Methods

This study performed three-dimensional perineal ultrasound scanning of the anal sphincter complex of 157 primiparas 42 days after delivery. Among them, 77 were in caesarean delivery (spontaneous delivery group) and 80 were in caesarean section (caesarean delivery group) from September 2018 to December 2020 in our hospital. The thickness of the end plane, the middle plane, the distal plane and the distal plane of the external anal sphincter at 3, 6, 9, 12 o'clock direction, and measure the thickness of the central plane of the pubic rectum muscle at 4, 8 o'clock direction. At the same time, the study used tomography and volume contrast imaging to observe the morphology and integrity of the anal sphincter complex.

Results

The thickness of the distal anal sphincter at the 12 o'clock direction, the proximal anal sphincter at 6, 12 o'clock, and the central plane at 9 and 12 o'clock in the obstetric group were smaller than those in the caesarean section group (all P < 0.05). There were no significant differences in the thickness of the remaining anal internal and external anal sphincter and puborectalis muscles between the two groups in different directions (all P> 0.05). In the obstetric group, a perineal sphincter defect was found via three-dimensional perineal ultrasound.

Conclusion

The delivery method has a certain influence on the shape of the anal sphincter complex. The thickness of the internal and external anal sphincter of the primiparous women in a certain direction is significantly smaller than that of caesarean section. Transperineally three-dimensional ultrasound can clearly show the morphological characteristics and integrity of the anal sphincter complex, and diagnose the defect of the anal sphincter complex.

Perianal ultrasound (PAUS): visualization of sphincter muscles and comparison with digital-rectal examination (DRE) in females

Background

The aim of this study was to determine the reproducibility and tolerance of perianal ultrasound (PAUS) and detect differences in sphincter muscles between various measuring positions and different maneuvers. PAUS was compared to digital-rectal examination (DRE) to see if sphincter contraction is visible and gradable in ultrasound volumes.

Methods

Fifty women underwent a medical history, DRU and PAUS by two uro-gynecologists in a prospective trial. PAUS volumes were measured via different parameters in different maneuvers. Examiners’ DRE impressions of sphincter tone were scaled with the DRESS-score. All patients completed a questionnaire.

Results

Thirty-five patients with complete PAUS and DRE were included in the study. Fifteen patients were excluded due to poor ultrasound volume quality or sphincter defects. Comparison of sphincter muscle thickness at different positions in PAUS showed significant differences between 6 and 12 o’clock positions (12 > 6 o’clock) and diameters (horizontal > vertical). No difference was found between the examiners. In comparison of rest and contraction only the vertical diameter changed. There was a negative but not significant correlation between PAUS measurements and DRESS-scores. Twenty-six patients completed the questionnaire that revealed women preferred PAUS over DRE.

Conclusion

PAUS is a reproducible and good tool to visualize the anal canal. It is comfortable for patients and easily handled by examiners. Sphincter muscle contraction is iso-volumetric. Vertical diameter changes during contraction leading the anal canal change its shape to oval due to external influence. PAUS is the ideal additional tool to visualize relevant structures that are palpable on DRE.

Comparing the diagnostic accuracy of 3 ultrasound modalities for diagnosing obstetric anal sphincter injuries

BACKGROUND

The optimal imaging modality of obstetric anal sphincter injuries needs to take into consideration convenience, availability, and ability to assess the sphincter morphologic condition. Endoanal ultrasound imaging currently is regarded as the reference standard, but it is not widely available in obstetric units. Exoanal alternatives exist, such as 3-dimensional introital or transperineal ultrasound imaging, which are already readily available in most obstetrics and gynecology units.

OBJECTIVE

The primary objective was to evaluate the diagnostic accuracy of 3-dimensional introital and 3-dimensional transperineal ultrasound imaging compared with 3-dimensional endoanal ultrasound imaging as the reference standard for the detection of anal sphincter defects in women who sustained obstetric anal sphincter injuries. The secondary objective was to correlate a diagnosis of anal sphincter defect on imaging to symptoms of anal incontinence, and to assess patient discomfort that is experienced for each imaging modality.

STUDY DESIGN

A cross-sectional study was conducted of 250 women who sustained obstetric anal sphincter injuries, all of whom underwent 3-dimensional introital, transperineal, and endoanal ultrasound imaging. Introital and transperineal ultrasound imaging were assessed with tomographic ultrasound imaging. All of the women completed a validated modified St Mark's Score and Visual Analogue Score for discomfort. Optimal cut-off values for a significant defect on tomographic ultrasound imaging were defined as those with the greatest sensitivity and specificity based on receiver operating characteristic curves with endoanal ultrasound imaging as the reference standard. Diagnostic test characteristics of introital and transperineal ultrasound imaging were calculated with the use of these optimal cut-offs.

RESULTS

Optimal cut-off for a significant external anal sphincter defect was ≥3 of 7 slices; sensitivity and specificity were 0.65 and 0.75 on introital imaging and 0.70 and 0.69 on transperineal ultrasound imaging. Optimal cut-off for a significant internal anal sphincter defect was ≥2 of 5 slices; sensitivity and specificity were 0.59 and 0.84 on introital imaging and 0.43 and 0.97 on transperineal ultrasound imaging. The area under the curve for the diagnosis of external and internal anal sphincter defects ranged from 0.70-0.74 (P<.001) for introital and transperineal imaging. Positive predictive value for external and internal sphincter defects ranged from 0.37-0.63, and negative predictive value ranged from 0.85-0.93 for introital and transperineal ultrasound imaging. Endoanal ultrasound imaging was the only modality for a defect to correlate with symptoms; mean modified St. Mark's score for a defect sphincter was 2.4 (standard deviation, 4.1) and for an intact sphincter was 0.9 (standard deviation, 2.7; P<.01). Introital and transperineal ultrasound imaging were associated with less discomfort than endoanal ultrasound imaging.

CONCLUSION

Endoanal ultrasound imaging remains the most accurate diagnostic imaging modality. With low positive predictive values, introital and transperineal ultrasound imaging are not suitable for the identification of sphincter defects; however, high negative predictive values show a good ability to detect an intact sphincter. The optimal cut-off number of slices on tomographic ultrasound imaging for external and internal anal sphincters allows for standardization of a significant defect. In women with a history of obstetric anal sphincter injuries, introital and transperineal ultrasound imagings are suitable to screen for an intact sphincter if endoanal ultrasound imaging is not available. When defects are found, women should then have endoanal ultrasound imaging to verify the diagnosis.

Use of 2D and multislice transperineal ultrasonography to describe the degree of perineal laceration following vaginal delivery

Background: Perineal tear is the most common complication after vaginal delivery. Pill-rolling test is a widely used clinical evaluation method to determine the degree of perineal tear. However, the evaluation results of anal sphincter complex (ASC) differ between clinical examination and 2D/multislice transperineal ultrasonography (TPUS). This study aims to describe measurement variation between these modalities.Methods: This cross-sectional study was conducted at Cipto Mangunkusumo Hospital from November 2015 to May 2016. Subjects were primiparous women after vaginal delivery. Clinical examination using pill-rolling test was performed to determine the degree of perineal laceration. Suture was conducted accordingly. The subjects were subjected to 2D/multislice TPUS 72 hours after delivery to evaluate the integrity of internal and external anal sphincters. Data were collected and analyzed to determine compatibility between these examinations.Results: Among 70 prospective primiparous women, five were excluded due to unavailability to undergo 2D/multislice TPUS 72 hours after delivery. The mean duration to perform 2D/multislice TPUS was 4.5 minutes, and pain was tolerable during the examination. The compatibility values of clinical examination with 2D and multislice TPUS were 0.98 and 0.93, respectively, with Cohen’s kappa of 0.92 (95% CI 0.81–1.00) and 0.79 (95% CI 0.58–0.99), respectively.Conclusion: Clinical examination is compatible with 2D/multislice TPUS for determining the degree of perineal tear after vaginal delivery.

Pelvic floor symptoms and quality of life changes during first pregnancy: a prospective cohort study

INTRODUCTION AND HYPOTHESIS

We describe pelvic floor function in nulliparous pregnant women.

MATERIALS AND METHODS

Nulliparous midwifery patients completed the Incontinence Severity Index (ISI), Pelvic Floor Impact Questionnaire (PFIQ-7), Wexner Fecal Incontinence Scale (W), and answered questions about sexual activity and perineal pain at baseline during the first (T1), second (T2), or third trimester (T3) and repeated in late T3. They also underwent a Pelvic Organ Prolapse Quantification (POP-Q) exam at their baseline visit. Data were compared across trimesters. Analysis of variance (ANOVA) and logistic regression accounted for repeated measures and was controlled for age and education.

RESULTS

We recruited 627 women. In T1, 124 women gave baseline data and completed questionnaires; in T2, 403; and in early T3, 96 (496 repeated questionnaires in later T3). Besides an increase in genital hiatus and perineal body (all adjusted p < .05), physical exam measures did not differ between trimesters. As pregnancy progressed, urinary incontinence (UI) (T1 = 33, T2 = 44, T3 = 69% women with ISI >0, all comparisons p < .02) and Incontinence Impact Questionnaire (IIQ-7) scores increased. Fecal incontinence (FI) increased (T1 = 8, T2 = 15, T3 = 16% from T2 to T3, p = .04); the Colorectal-Anal Impact Questionnaire (CRAIQ-7) scores did not. Perineal pain increased (T1 = 17, T2 = 18 and T3 = 40%, all adjusted p < .001), and sexual activity decreased (T1 = 94, T2 = 90, T3 = 77% sexually active, T1 vs T3 and T2 vs T3, p < .001) as pregnancy progressed.

CONCLUSIONS

During pregnancy, women experience worsening UI, FI, and perineal pain. UI symptoms are associated with a negative impact on quality of life (QoL). Sexual activity decreased and POP-Q stage did not change.

The relationship of 3-D translabial ultrasound anal sphincter complex measurements to postpartum anal and fecal incontinence

INTRODUCTION AND HYPOTHESIS

We aimed to determine whether anal sphincter complex (ASC) measurements on translabial ultrasound (TL-US) were related to anal incontinence (AI) or fecal incontinence (FI) symptoms 6 months postpartum.

METHODS

A prospective cohort of primiparous women underwent TL-US 6 months after a vaginal birth (VB) or cesarean delivery (CD). Muscle thickness was measured at 3, 6, 9, and 12 o'clock positions of the external anal sphincter (EAS), the same four quadrants of the internal anal sphincter (IAS) at proximal, mid, and distal levels, and at the bilateral pubovisceralis muscle (PVM). Measurements were correlated to AI and FI on the Wexner Fecal Incontinence Scale, with sub-analyses by mode of delivery. The odds ratio (OR) of symptoms was calculated for every 1 mm increase in muscle thickness (E1MIT).

RESULTS

A total of 423 women (299 VB, 124 CD) had TL-US 6 months postpartum. Decreased AI risk was associated with thicker measurements at the 6 o'clock (OR 0.74 E1MIT) and 9 o'clock proximal IAS (OR 0.71 E1MIT) in the entire cohort. For CD women, thicker measurements of the 9 o'clock proximal IAS were associated with decreased risk of AI (OR 0.56 E1MIT) and thicker distal 6 o'clock IAS measurements were related to a decreased risk of FI (OR 0.37 E1MIT). For VB women, no sphincter measurements were significantly related to symptoms, but thicker PVM measurements were associated with increased risk of AI (right side OR 1.32 E1MIT; left side OR 1.21 E1MIT).

CONCLUSIONS

ASC anatomy is associated with AI and FI in certain locations; these locations vary based on the patient's mode of delivery.