MRI in evaluating atrophy of the external anal sphincter in patients with fecal incontinence

A biomechanical perspective on perineal injuries during childbirth

BACKGROUND AND OBJECTIVE

Childbirth trauma is a major health concern that affects millions of women worldwide. Severe degrees of perineal trauma, designated as obstetric anal sphincter injuries (OASIS), and levator ani muscle (LAM) injuries are associated with long-term morbidity. While significant research has been conducted on LAM avulsions, less attention has been given to perineal trauma and OASIS, which affect up to 90% and 11% of vaginal deliveries, respectively. Despite being widely discussed, childbirth trauma remains unpredictable. This work aims to enhance the modeling of the maternal musculature during childbirth, with a particular focus on understanding the mechanisms underlying the often overlooked perineal injuries.

METHODS

A geometrical model of the pelvic floor muscles (PFM) and perineum (including the perineal body, ischiocavernosus, bulbospongiosus, superficial and deep transverse perineal muscles) was created. The muscles were characterized by a transversely isotropic visco-hyperelastic constitutive model. Two simulations of vaginal delivery were conducted with the fetus in the vertex presentation and occipito-anterior position, with and without the perineum.

RESULTS

The simulation that considered the perineum exhibited higher stresses over an extended area of the PFM, which suggests that including additional structures can impact the obtained results. The maximum stretch of the urogenital hiatus was 2.94 and the maximum stress was 23.86 kPa. The perineal body reached a maximum stretch of 1.95, which was more pronounced near the urogenital hiatus, where perineal tears may occur. The external anal sphincter's transverse diameter decreased by 51% and the maximum principal stresses were observed in the area close to the perineal body, where OASIS can occur.

CONCLUSIONS

The present study emphasizes the importance of including most structures involved in vaginal delivery in its biomechanical analysis and represents another step further in the understanding of perineal injuries and OASIS. The superior region of the perineal body and its connection to the urogenital hiatus and anal sphincter have been identified as the most critical regions, highly susceptible to injury.

Impact of sex and aging on radiographic and functional parameters of the anal sphincter complex in patients with accidental bowel leakage

AIMS

Treatment outcomes for accidental bowel leakage (ABL) may be influenced by age-related sarcopenia. We sought to determine if thickness of the anal sphincter complex on endoanal ultrasound correlated with function in women and men with ABL and if women demonstrated age-related anal sphincter thinning.

METHODS

Consecutive patients with ABL presenting to our pelvic floor clinic from 2012 to 2017 were included. Clinical data were obtained from medical records. External anal sphincter (EAS), imaged by endoanal ultrasound at proximal, mid and distal locations, and IAS thickness were measured at 12, 3, 6, and 9 o'clock; puborectalis muscle (PRM) was measured at 4, 6, and 8 o'clock; and averaged. Anorectal manometry was conducted when clinically indicated. Data were compared using Mann-Whitney tests and linear regression. Results are reported as mean ± SD or median (IQR).

RESULTS

Women (n = 136) were younger than men (n = 26) (61 ± 13 vs. 67 ± 13 years, p = 0.02). More women than men had pelvic surgery and less had colorectal surgery, spinal disorders, or a history of smoking (p < 0.05). Eighty-two percentage of women had an anal sphincter defect versus 31% of men (p < 0.01). All anal sphincter complex components were thinner in women than men with lower squeeze and resting pressures (p < 0.03), even in nulliparous women. Mean resting pressure was lower in older 6.1 (4.6-7.8) versus younger women 8.3 (5.0-12.9) mmHg, p = 0.04.

CONCLUSIONS

Women, even nulliparous, with ABL demonstrate thinner and weaker anal sphincters than men, Aging correlated with an increase in anal sphincter thickness, suggesting that age-related changes in the intrinsic components of the anal sphincter complex associated with ABL are complex and are not always well demonstrated on endoanal ultrasound.

MRI of Recurrent Fistula-in-Ano: Is it Different from Treatment-Naïve Fistula-in-Ano and How Does it Correlate with Anal Sphincter Morphology?

Objectives  The main aim of this study was to compare magnetic resonance imaging (MRI) findings of recurrent and treatment-naïve fistula-in-ano and to correlate imaging findings with anal sphincter morphology in recurrent fistula-in-ano. Methods  This is a retrospective study of adult patients who underwent MRI for suspected fistula-in-ano in 2018. After excluding patients with alternative diagnosis, patients were stratified into recurrent ( n  = 103) and treatment-naïve ( n  = 106) fistula-in-ano groups. Two blinded radiologists reread MRI scans in consensus for fistula characteristics and anal sphincter morphology. We compared imaging features of recurrent and treatment-naïve fistula-in-ano, assessed the incidence of anal sphincter scarring among patients with recurrent fistula-in-ano, and studied its association with fistula features. Results  Two-hundred nine patients (187 males) with mean age of 40.6 (standard deviation: 12.2) years were included. Trans-sphincteric, inter-sphincteric, extra-sphincteric, and supra-sphincteric fistula-in-ano were seen in 63.6, 33, 2.9, and 0.5%, respectively. There were secondary tracts, supralevator extension, and secondary cause for fistula in 49.3, 12.9, and 14.8%, respectively. There was no difference between the fistula features of recurrent and treatment-naïve fistula-in-ano, except for significantly fewer external openings among recurrent fistula-in-ano ( p  = 0.005). Among patients with recurrent fistula-in-ano, MRI detected anal sphincter defect/scarring was seen in 53.4% ( n  = 55) and was significantly associated with posterior fistula-in-ano ( p  = 0.031), collections and/or supralevator extension ( p  = 0.010), and secondary tracts ( p  = 0.015). Conclusion  Fistula features of recurrent and treatment-naïve patients were mostly similar. There was high incidence (53.4%) of MRI-identified anal sphincter scarring/defect among recurrent fistula-in-ano, which was significantly associated with posterior fistula, collections, supra or translevator extension, and secondary tracts. Key Points MRI-identified anal sphincter scarring is very common among patients with recurrent fistula-in-ano and seen in more than half of them.There was significantly higher incidence of sphincter scarring among patients who had posterior fistula, collections, supralevator/translevator extension, and secondary tracts.

Guidelines on postoperative magnetic resonance imaging in patients operated for cryptoglandular anal fistula: Experience from 2404 scans

Magnetic resonance imaging (MRI) is considered the gold standard for the evaluation of anal fistulas. There is sufficient literature available outlining the interpretation of fistula MRI before performing surgery. However, the interpretation of MRI becomes quite challenging in the postoperative period after the surgery of fistula has been undertaken. Incidentally, there are scarce data and no set guidelines regarding analysis of fistula MRI in the postoperative period. In this article, we discuss the challenges faced while interpreting the postoperative MRI, the timing of the postoperative MRI, the utility of MRI in the postoperative period for the management of anal fistulas, the importance of the active involvement and experience of the treating clinician in interpreting MRI scans, and the latest advancements in the field.

Diagnostic approach to faecal incontinence: What test and when to perform?

Faecal incontinence (FI) is a debilitating common end result of several diseases affecting the quality of life and leading to patient disability, morbidity, and increased societal burden. Given the various causes of FI, it is important to assess and identify the underlying pathomechanisms. Several investigatory tools are available including high-resolution anorectal manometry, transrectal ultrasound, magnetic resonance imaging, and electromyography. This review article provides an overview on the causes and pathophysiology of FI and the author’s perspective of the stepwise investigation of patients with FI based on the available literature. Overall, high-resolution anorectal manometry should be the first investigatory tool for FI, followed by either transrectal ultrasound or magnetic resonance imaging for anal internal sphincter and external anal sphincter injury, respectively.

MR defecography review

Pelvic floor dysfunction is a relatively common but often complex condition, presenting with a variety of clinical symptoms, especially when it involves multiple compartments. Clinical exam alone is often inadequate and requires a complementary imaging study. Magnetic resonance defecography (MRD) is an excellent noninvasive diagnostic study with its multiplanar capability, lack of ionizing radiation and excellent soft tissue resolution. It can identify both anatomic and functional abnormalities in the pelvic floor and specifically excels in its ability to simultaneously detect multicompartmental pathology and help with vital pre-operative assessment. This manuscript reviews the relevant anatomical landmarks, describes the optimal technique, highlights an approach to the interpretation of MRD, and provides an overview of the various pelvic floor disorders in the different anatomical compartments.

Multimodality imaging of pelvic floor anatomy

The pelvic floor is composed of a network of muscles, ligaments, and fasciae, which provide active and passive support for the pelvic organs. Impairment of these pelvic floor elements can result in a variety of functional abnormalities and single or multicompartment organ prolapse. Knowledge of normal pelvic floor anatomy can aid the radiologist in understanding the complex nature of pelvic floor dysfunction and is important for comprehensive image interpretation. This article provides an overview of normal anatomy of the pelvic floor as seen on magnetic resonance imaging, ultrasound, and fluoroscopic studies performed in the evaluation of pelvic floor function.

Magnetic resonance imaging of the anal sphincter and spine in patients with anorectal malformations after posterior sagittal anorectoplasty: a late follow-up cross-sectional study

PURPOSE

We aimed to assess the association of fecal incontinence to the anatomy of the anal sphincter complex and lower bony spinal anomalies as investigated with magnetic resonance imaging (MRI) in adolescents and adults with anorectal malformations (ARM) after posterior sagittal anorectoplasty (PSARP).

METHODS

We conducted a cross-sectional study in 20 patients with ARM after PSARP. Anatomy of the anorectum and spine were examined with MRI and functional outcome assessed with the Wexner incontinence score.

RESULTS

We included 20 patient (12 males) had a median age of 19.5 years (14-27). One patient was excluded leaving 19 patients for outcome analysis. Fecal incontinence was found in 12 out of 19 patients (63%). Interposed fat was present in 9 patients (47%). The presence (r = 0.597, p = 0.012) and thickness of interposed fat (r = 0.832, p = 0.005) between the anal sphincter complex and bowel were positively correlated to the Wexner fecal incontinence score. No correlation was found between lower bony spinal anomalies and fecal incontinence.

CONCLUSIONS

A positive correlation between interposed fat and higher Wexner fecal incontinence score was found indicating a more severe fecal incontinence but no other correlation between anatomy of the anal sphincter complex and neorectum to functional bowel outcome was observed.

Assessing Anorectal Function in Constipation and Fecal Incontinence

Constipation and fecal incontinence are commonly encountered complaints in the gastrointestinal clinic. Assessment of anorectal function includes comprehensive history, rectal examination, and prospective stool diary or electronic App diary that accurately captures bowel symptoms, evaluation of severity, and quality of life of measure. Evaluation of a suspected patient with dyssynergic constipation includes anorectal manometry, balloon expulsion test, and defecography. Investigation of a suspected patient with fecal incontinence includes high-resolution anorectal manometry; anal ultrasound or MRI; and neurophysiology tests, such as translumbosacral anorectal magnetic stimulation or pudendal nerve latency. This article provides an approach to the assessment of anorectal function.

MRI anatomy and pathology of the anal canal

The normal function of the anal sphincter complex is crucial for quality of life, as it is the mechanism by which fecal continence is maintained. Additionally, the anal sphincter complex is an integral part of the coordinated effort of defecation. As imaging plays an important role in assessment of pathologic conditions involving the anal region, understanding the normal anatomy of the anal sphincter complex is important for correct image interpretation and accurate diagnosis. This review discusses the anatomy and function of the anal sphincter complex, important technical considerations for MRI, and various inflammatory, infectious, and neoplastic processes, as well as pathologic structural conditions that affect the anal region. Level of Evidence: 5 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:1018-1032.

Comparison of 3D endoanal ultrasound and external phased array magnetic resonance imaging in the diagnosis of obstetric anal sphincter injuries

Objectives

The gold standard of postpartum anal sphincter imaging has been the 3D endoanal ultrasound (EAUS). Development of magnetic resonance imaging (MRI) has allowed anal sphincter evaluation without the use of endoanal coils. The aim of this study is to compare these two modalities in diagnosing residual sphincter lesions post obstetric anal sphincter injury (OASI).

Methods

Forty women were followed up after primary repair of OASI with both 3D EAUS and external phased array MRI. Details of the anal sphincter injury and sphincter musculature were gathered and analysed.

Results

There was a moderate interrater reliability (κ = 0.510) between the two imaging modalities in detecting sphincter lesions, with more lesions detected by MRI. There was a moderate intraclass correlation (ICC) between the circumference of the tear (κ = 0.506) and a fair ICC between the external anal sphincter thickness measurements at locations 3 and 9 on the proctologic clock face (κ = 0.320) and (κ = 0.336).

Conclusions

The results of our study indicate that the use of external phased array MRI is feasible for detecting obstetric anal sphincter lesions postpartum. This allows for imaging of the sphincter defects in centres where EAUS imaging is not available.

Key Points

• A two centre prospective study that showed external phased array MRI to be a valid imaging modality for diagnosing obstetric anal sphincter injuries.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06125-8) contains supplementary material, which is available to authorized users.

MRI of anal canal: common anal and perianal disorders beyond fistulas: Part 2

A broad spectrum of disease, from benign processes to life-threatening pathologies, can cause anal pain. MR imaging (MRI) has become increasingly widely used method over the past two decades for the evaluation of individuals with anorectal symptoms. Although imaging is rarely necessary to determine the etiology of the majority of cases, MRI is particularly useful as a noninvasive method of excluding severe neoplastic conditions. In this article, MRI findings of a number of pathologies such as anal and perianal neoplasms, hemorrhoidal disease, arteriovenous malformation of the perianal region, and anal sphincter lesions (defects, scarring, atrophy) which may lead to fecal incontinence are presented.

The immediate effect of vaginal and caesarean delivery on anal sphincter measurements

Objective

This study evaluated the effects of vaginal and caesarean delivery on internal and external anal sphincter muscle thickness using translabial ultrasonography (TL-US).

Methods

This prospective cohort study enrolled nulliparous women who either had vaginal or caesarean deliveries. The thickness of the hypoechoic internal anal sphincter (IAS) and hyperechoic external anal sphincter (EAS) at the 12, 3, 6, and 9 o’clock positions at the distal level were measured before delivery and within 24–48 h after delivery.

Results

A total 105 consecutive women were enrolled in the study: 60 in the vaginal delivery group and 45 in the caesarean delivery group. The IAS muscle thickness at the 12 o’clock position in the vaginal delivery group was significantly thicker before compared with after delivery (mean ± SD: 2.31 ± 0.74 mm versus 1.81 ± 0.64 mm, respectively). The EAS muscle thickness at the 12 o’clock position in the vaginal delivery group was significantly thicker before compared with after delivery (mean ± SD: 2.42 ± 0.64 mm versus 1.97 ± 0.85, respectively).

Conclusions

There was significant muscle thinning of both the IAS and EAS at the 12 o’clock position after vaginal delivery, but not after caesarean delivery.

Clinical symptoms related to anal sphincter defects and atrophy on external phased-array MR imaging

INTRODUCTION AND HYPOTHESIS

Defecatory complaints have a severe impact on quality of life. The additional value of pelvic floor MRI in patients with defecatory complaints is unclear. Our aim was to correlate the presence of defects and atrophy of the anal sphincter complex using pelvic floor MRI in women with mixed pelvic floor symptoms and to establish patient characteristics and self reported complaints predictive of pathology.

METHODS

This is a retrospective study among women with mixed pelvic floor symptoms who underwent external phased-array MRI and completed a questionnaire on bothersome defecatory complaints. Data on patient characteristics, including obstetrical history and questionnaire scores were correlated with the assessment of anal sphincter defects and atrophy on pelvic floor MRI.

RESULTS

One hundred and fifty-eight women were included. A defect of the external anal sphincter (EAS) and internal anal sphincter (IAS) was found in 18 (11%) and 5 (3%) patients respectively. Atrophy of the EAS was present in 72 patients (46%), with more cases of mild (n = 52, 33%) than severe atrophy (n = 20, 13%). The variable "previous third or fourth degree tear" had a significant positive association with an IAS defect on MRI, with an OR of 9.533 (1.425-63.776). Patients with EAS atrophy had higher scores for fecal incontinence (indicating more bother) than patients without EAS atrophy. Higher age and BMI were true predictors of the presence of more severe EAS atrophy.

CONCLUSION

Atrophy of the EAS was highly prevalent in this population and was associated with bothersome symptoms of fecal incontinence.

ACR Appropriateness Criteria pelvic floor dysfunction

Pelvic floor dysfunction is a common and potentially complex condition. Imaging can complement physical examination by revealing clinically occult abnormalities and clarifying the nature of the pelvic floor defects present. Imaging can add value in preoperative management for patients with a complex clinical presentation, and in postoperative management of patients suspected to have recurrent pelvic floor dysfunction or a surgical complication. Imaging findings are only clinically relevant if the patient is symptomatic. Several imaging modalities have a potential role in evaluating patients; the choice of modality depends on the patient's symptoms, the clinical information desired, and the usefulness of the test. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions; they are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals, and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Long-term function and morphology of the anal sphincters and the pelvic floor after primary repair of obstetric anal sphincter injury

AIM

More than 50% of women experience deteriorating continence over time following primary repair of obstetric anal sphincter injuries. The objectives of this study were to assess the function and morphology of the anal sphincters and pelvic floor in women with long-term faecal incontinence after sphincter repair (primary end-point) and to evaluate their correlation with severity of incontinence (secondary end-point).

METHOD

The participants in this prospective study were recruited from a cohort of all women who sustained third or fourth degree obstetric sphincter injury reconstruction (cases) from January 1976 to November 1991. The women who delivered immediately before and after each case, without sustaining obstetric damage, were included as controls. Cases and controls were stratified into three categories: (i) continent; (ii) minor incontinence; and (iii) severe incontinence. The function and morphology of the anal sphincters and pelvic floor were evaluated by MRI, three-dimensional endoanal ultrasonography and anorectal physiology tests.

RESULTS

Fifty-nine women (29 cases/30 controls; mean age 51/53 years; mean follow-up 23.7/24.1 years, respectively) were assessed. Morphologically, cases had a significantly shorter anterior external anal sphincter length compared with controls when evaluated by three-dimensional endoanal ultrasonography (8.6 vs 10.2 mm; P = 0.03). Functionally, cases with severe incontinence had a significantly shorter anterior sphincter length compared with cases with minor incontinence (7.7 vs 10.4 mm; P = 0.04). No correlation could be found between anal pressures and severity of incontinence in the case group.

CONCLUSIONS

Cases had a significantly shorter anterior external anal sphincter length. Functionally, anterior sphincter length correlated with increased severity of incontinence.

Anorectal anatomy and imaging techniques

The rectum and anus are two anatomically complex organs with diverse pathologies. This article reviews the basic anatomy of the rectum and anus. In addition, it addresses the current radiographic techniques used to evaluate these structures, specifically ultrasound, magnetic resonance imaging, and defecography.

Anorectal physiology and testing

A good understanding of anorectal physiology is essential for the diagnosis and appropriate treatment of various anorectal disorders, such as fecal incontinence, constipation, and pain. This article reviews the physiology of the anorectum and details the various investigations used to diagnose anorectal physiology disorders. These anatomic and functional tests include anal manometry, endoanal ultrasound, defecography, balloon expulsion test, magnetic resonance imaging, pudendal nerve terminal motor latency, electromyography, and colonic transit studies. Indications for investigations, steps in performing the tests, and interpretation of results are discussed.

Preoperative mapping of fistula-in-ano: a new three-dimensional MRI-based modelling technique

AIM

We aimed to develop an intuitive, interactive, three-dimensional (3D) MRI modelling technique to produce a 3D image of fistula-in-ano.

METHOD

The 3D model was created from standard two-dimensional (2D) MRI sequences to produce an image that is anatomically correct. Individual muscle and soft-tissue layers were extracted from T1-weighted sequences and fistula pathology from short TI inversion recovery (STIR) sequences, to produce two separate volumes. These were then fused using postprocessing software (Vitrea Workstation version 6.3) to generate a 3D model.

RESULTS

The final 3D model was incorporated into a PDF file that has an integrated computer aided design (CAD) viewer, allowing the surgeon to rotate it in any direction during preoperative planning or whilst in theatre.

CONCLUSION

As an adjunct to 2D MRI images and the associated radiology report, this model communicates the fistula anatomy to the clinician more clearly and should be particularly useful in complex cases.

Postpartum translabial 2D and 3D ultrasound measurements of the anal sphincter complex in primiparous women delivering by vaginal birth versus Cesarean delivery

INTRODUCTION AND HYPOTHESIS

Consensus on normal translabial ultrasound (TL-US) anal sphincter complex measurements for postpartum women is lacking. We aimed to evaluate normative measurements in 2D and 3D TL-US for the anal sphincter complex (ASC) at 6 months postpartum and compare these measurements in women who had a vaginal birth (VB) and in those who had a Cesarean delivery (CD).

METHODS

A large, prospective cohort of primiparous women underwent 2D and 3D TL-US 6 months after their first delivery. For normative sphincter measurements, we excluded women with third- or fourth-degree lacerations or with sphincter interruption on TL-US. Measurements included the sphincter thickness at the 3, 6, 9, and 12 o'clock positions of the external anal sphincter (EAS) and the internal anal sphincter (IAS) at proximal, mid, and distal levels. We also measured the mean coronal diameter of the pubovisceralis muscle (PVM).

RESULTS

696 women consented to participate, and 433 women presented for ultrasound imaging 6 months later. Women who sustained a third- or fourth-degree laceration had significantly thicker EAS measurements at 12 o'clock. Sphincter asymmetry was common (69 %), but was not related to mode of delivery. Only IAS measurements at the proximal and distal 12 o'clock position were significantly thicker for CD patients. There were no significant differences in the EAS or PVM measurements between VB and CD women.

CONCLUSIONS

There appear to be few differences in normative sphincter ultrasound measurements between primiparous patients who had VB or CD.

[3.0T MRI with a high resolution protocol for the study of benign disease of the anus and rectum. Part 2: Anorectal inflammatory disease. Postsurgical anatomy and complications after treatment]

Benign anorectal disease comprises a broad group of processes with very diverse origins; these processes may be congenital or acquired as well as inflammatory or tumor related. However, benign anorectal disease has received less attention in the scientific literature than malignant disease. In this second part of this image-based review of benign anorectal disease, we describe the most common inflammatory and fistulous diseases, the postsurgical anatomy, and complications that can occur after surgical treatment or radiotherapy for anorectal disease.

[3.0 T MRI with a high resolution protocol for the study of benign disease of the anus and rectum. Part one: High resolution protocol for 3.0 T MRI, anatomic review, benign tumors, and congenital or acquired alterations of the sphincter complex]

Benign anorectal disease comprises a broad group of processes with very diverse origins; these processes may be congenital or acquired as well as inflammatory or tumor related. However, benign anorectal disease has received less attention in the scientific literature than malignant disease. We present an image-based review of the most common benign diseases of the anus and rectum. In this first part, we review the anatomy of the region and provide a brief description of the peculiarities of the high resolution protocol that we use with 3.0 T MRI. We go on to describe the most common benign anorectal tumors and developmental cystic lesions, together with their differential diagnoses, as well as congenital and acquired anomalies of the anorectal sphincter complex.

Sacral nerve stimulation for fecal incontinence related to external sphincter atrophy

BACKGROUND

Atrophy of the external anal sphincter, a pathologic muscle volume anomaly associated with fecal incontinence, has been shown to be a negative predictor of the outcome of surgery for defects of the external anal sphincter. It is unclear whether external anal sphincter atrophy also affects the outcome of sacral nerve stimulation for fecal incontinence.

OBJECTIVE

Our aim was to assess the effectiveness of sacral nerve stimulation in patients with fecal incontinence and external anal sphincter atrophy and to determine whether severity of atrophy and concomitant presence of a sphincter defect are negative predictors of outcome.

DESIGN

This was a prospective observational study of treatment outcome.

SETTING

The study was conducted from November 2004 through November 2010 at a regional hospital in Italy.

PATIENTS

Consecutive patients with fecal incontinence and external anal sphincter atrophy were included. By means of MRI, patients were determined to have either moderate (<50%) or severe (≥ 50%) thinning of and/or replacement of sphincter muscle by fat. The concomitant presence of defects of the external anal sphincter was also detected by MRI.

INTERVENTION

All patients underwent sacral nerve stimulation through a staged implantation procedure.

MAIN OUTCOME MEASURES

The main outcome measures were improvement in the Cleveland Clinic Florida Fecal Incontinence Scale (Wexner score), number of episodes of incontinence per week, and the Fecal Incontinence Quality of Life Scale.

RESULTS

A total of 28 patients underwent definitive implantation of the sacral nerve stimulation device. Wexner scores decreased from a median of 16 (range, 10-20) at baseline to 3 (range, 0-8) at 6-month follow-up (p < 0.001). Weekly incontinence episodes decreased from a mean (SD) of 14.7 (12.5) to 0.40 (0.82); p < 0.001. Improvement was significantly related to severity of fecal incontinence (r = 0.86; p < 0.001). Overall quality-of-life scores improved from a mean of 1.8 (0.6) to 3.8 (0.4);p < 0.001. Sacral nerve stimulation was effective in both moderate (n = 16) and severe (n = 12) atrophy and in patients with (n = 8) or without (n = 20) external anal sphincter defects.

LIMITATIONS

The study was limited by its observational nature and relatively small sample size.

CONCLUSIONS

Sacral nerve stimulation can be effective in restoring continence and improving quality of life in patients with fecal incontinence related to atrophy of the external anal sphincter, regardless of the severity of atrophy. Moreover, the presence of EAS atrophy does not influence the success of the outcome of SNS in patients with a sphincter defect. These findings are consistent with the hypothesis that the effects of SNS are not achieved solely by its action on the anal sphincter complex.

Preoperative MRI sphincter morphology and anal manometry: can they be markers of functional outcome following anterior resection for rectal cancer?

AIM

Good functional outcome following anterior resection (AR) for rectal cancer is an important clinical goal, but its prediction has proven difficult. Assessments such as anal manometry have been advocated as a potential tool but functional anatomy as depicted on MRI has not been investigated. This study looked at whether sphincter complex measurements recorded from preoperative staging MRIs and preoperative anal manometry have any correlation with functional outcome.

METHOD

Consecutive patients with rectal adenocarcinoma underwent preoperative manometric assessment and MRI staging. MRIs were assessed with regard to anorectal angle, puborectalis thickness, canal length and external and internal anal sphincter thickness. Functional outcome was categorized into three groups according to the number of adverse postoperative symptoms (frequency, urgency, leakage, diarrhoea, use of pads, use of antidiarrhoeal medication): 0, 1 and ≥ 2. This was evaluated 1 year following surgery and 6 months following stoma reversal where applicable. Univariate analysis of an ordinal regression model was performed with significance at the 5% level.

RESULTS

Thirty patients were assessed. No single preoperative manometric parameter proved significant (P > 0.05). Only puborectalis thickness showed a significant (P = 0.01) relationship with the number of adverse symptoms suffered postoperatively. On receiver operating characteristics analysis, a cut-off value of 3.5 mm gave an optimal sensitivity of 0.5 (95% CI, 0.17-0.83) and specificity of 0.86 (95% CI, 0.64-0.96).

CONCLUSIONS

Measurements of the puborectalis thickness on preoperative staging MRIs for rectal cancer may help predict functional outcome following AR. Prospective assessment of larger numbers with a fully validated continence score are required to evaluate these findings further.

Endo-anal ultrasound versus endo-anal magnetic resonance imaging for the depiction of external anal sphincter pathology in patients with faecal incontinence: a systematic review

Objective: To evaluate the endo-anal ultrasound (EAUS) versus endo-anal magnetic resonance imaging (EAMRI) in the diagnosis of external anal sphincter defects (EAS) in patients with faecal incontinence (FI). Methods: Studies on EAUS and EAMRI were selected and analyzed to generate summative data. Results: Five studies encompassing 347 patients of FI were included in this review. Three studies validated the results of EAUS and EAMRI by surgery (61 patients). In the fixed effect model, EAUS was superior to EAMRI in the depiction of EAS defects. On combined analysis of five studies using fixed effect model, both EAUS and EAMRI were equally effective. However, there was a significant heterogeneity between studies. Conclusion: EAUS and EAMRI are comparable in the diagnosis of EAS defects in patients of FI. Since EAUS is an economical, quicker and easily available imaging modality, it may be used a preferable investigation for the diagnosis of EAS defects in patients of FI.

Imaging pelvic floor dysfunction

Pelvic floor function and structure are complex, and imaging (integrated with an understanding of physiology) is central to guiding the clinician in managing patients with incontinence, constipation, difficult rectal evacuation and pelvic organ prolapse. Multimodal imaging techniques such as static and dynamic imaging techniques (sometimes combined in a single sitting) have revolutionised our understanding of functional anatomy. The advent of endo-luminal imaging has increased our spatial resolution by its closer proximity to the area of interest. Dynamic imaging gives us a near physiological data set which helps us to simulate what is likely to happen in real life and gives us a better understanding of the multifactorial causes, and consequences, of pelvic floor dysfunction.

Reproducibility of dynamic MR imaging pelvic measurements: a multi-institutional study

PURPOSE

To assess the reproducibility of bone and soft-tissue pelvimetry measurements obtained from dynamic magnetic resonance (MR) imaging studies in primiparous women across multiple centers.

MATERIALS AND METHODS

All subjects prospectively gave consent for participation in this institutional review board-approved, HIPAA-compliant study. At six clinical sites, standardized dynamic pelvic 1.5-T multiplanar T2-weighted MR imaging was performed in three groups of primiparous women at 6-12 months after birth: Group 1, vaginal delivery with anal sphincter tear (n = 93); group 2, vaginal delivery without anal sphincter tear (n = 79); and group 3, cesarean delivery without labor (n = 26). After standardized central training, blinded readers at separate clinical sites and a blinded expert central reader measured nine bone and 10 soft-tissue pelvimetry parameters. Subsequently, three readers underwent additional standardized training, and reread 20 MR imaging studies. Measurement variability was assessed by using intraclass correlation for agreement between the clinical site and central readers. Acceptable agreement was defined as an intraclass correlation coefficient (ICC) of at least 0.7.

RESULTS

There was acceptable agreement (ICC range, 0.71-0.93) for eight of 19 MR imaging parameters at initial readings of 198 subjects. The remaining parameters had an ICC range of 0.13-0.66. Additional training reduced measurement variability: Twelve of 19 parameters had acceptable agreement (ICC range, 0.70-0.92). Correlations were greater for bone (ICC, >or=0.70 in five [initial readings] and eight of nine [rereadings] variables) than for soft-tissue measurements (ICC, >or=0.70 in three [initial readings] of 10 and four [rereadings] of 10 readings, respectively).

CONCLUSION

Despite standardized central training, there is high variability of pelvic MR imaging measurements among readers, particularly for soft-tissue structures. Although slightly improved with additional training, measurement variability adversely affects the utility of many MR imaging measurements for multicenter pelvic floor disorder research.

Diagnostic precision of endoanal MRI in the detection of anal sphincter pathology: a meta-analysis

OBJECTIVE

This study aims to evaluate the diagnostic precision of endoanal magnetic resonance imaging in identifying anal sphincter injury and/or atrophy when compared with either endoanal ultrasound or surgical diagnosis.

MATERIALS AND METHODS

Quantitative meta-analysis was performed on nine studies, comparing endoanal MRI with endoanal ultrasound or surgical diagnosis in 157 patients. Sensitivity, specificity, and diagnostic odds ratio were calculated for each study. Summary receiver operating characteristic curves (SROC) and subgroup analysis were undertaken.

RESULTS

The overall sensitivity and specificity of endoanal MRI for external sphincter injury was 0.78 (95%CI: 0.66-0.84) and 0.66 (95%CI: 0.51-0.79), respectively. For internal sphincter injury detection, this was 0.63 (95%CI: 0.50-0.74) and 0.71 (95%CI: 0.60-0.81), respectively. For detection of atrophy, this was 0.86 (95%CI: 0.71-0.95) and 0.82 (95%CI: 0.65-0.93), respectively. The area under the SROC curve and diagnostic odds ratio were 0.84 (SE = 0.07) and 6.14 (95%CI: 2.17-17.4) for external sphincter injury, 0.79 (SE = 0.07) and 4.60 (95%CI: 1.75-12.15) for internal sphincter injury, and 0.92 (SE = 0.08) and 21.49 (95%CI: 2.87-160.64) for sphincter atrophy.

CONCLUSION

Endoanal MRI was sensitive and specific for the detection of external sphincter injury and especially sphincter atrophy. It may be useful as an alternative to endoanal ultrasound in patients presenting with fecal incontinence, although further clinical studies are needed to identify its best application in clinical practice.

Pelvic floor muscle lesions at endoanal MR imaging in female patients with faecal incontinence

To evaluate the frequency and spectrum of lesions of different pelvic floor muscles at endoanal MRI in women with severe faecal incontinence and to study their relation with incontinence severity and manometric findings. In 105 women MRI examinations were evaluated for internal anal sphincter (IAS), external anal sphincter (EAS), puborectal muscle (PM) and levator ani (LA) lesions. The relative contribution of lesions to differences in incontinence severity and manometric findings was studied. IAS (n = 59) and EAS (n = 61) defects were more common than PM (n = 23) and LA (n = 26) defects. PM and LA defects presented mainly with IAS and/or EAS defects (isolated n = 2 and n = 3). EAS atrophy (n = 73) was more common than IAS (n = 19), PM (n = 16) and LA (n = 9) atrophy and presented mainly isolated. PM and LA atrophy presented primarily with EAS atrophy (isolated n = 3 and n = 1). Patients with IAS and EAS lesions had a lower resting and squeeze pressure, respectively; no other associations were found. PM and LA lesions are relatively common in patients with severe faecal incontinence, but the majority of lesions are found in women who also have IAS and/or EAS lesions. Only an association between anal sphincter lesions and manometry was observed.

[Morphologic evaluation of fecal incontinence by magnetic resonance imaging in patients with corrected anal atresia]

PURPOSE

To describe the findings obtained with magnetic resonance imaging (MRI) in patients with ano-rectal atresia, after treatment by posterior sagittal anorectoplasty (PSARP), who have fecal incontinence and to describe its usefulness in the evaluation of causes of incontinence.

SUBJECT AND METHODS

Twelve patients, 9 men and 3 women, with anorectal atresia were examined with 0.5T MRI after performing PSARP for imperforate anus. The study included T1-weighted, T2-weighted and proton-density, axial, sagittal and coronal planes. The location of descended neorectus and the degree of development of pelvic musculature were evaluated.

RESULTS

Normal development of anus levator muscles and sphincterian complex were observed in six patients, with correct situation of neorectus between anus levator muscles and sphincterian complex in five of them and eccentric in the other one. Diverse grades of striate muscular complex underdevelopment were showed in the other six cases, moderate grade in four of them and severe hypoplasia in the other two. Spinal and urogenital congenital anomalies were found in these patients. Sagittal and coronal T1-weighted MR images were the most useful planes in evaluating the relationship between anus levator muscles and sphincterian complex and axial T1-weighted MR images in the evaluation of the level of development of striated muscle complex in the evaluation of patients.

CONCLUSIONS

MRI is useful in the evaluation of patients with fecal incontinence after performing PSARP for anorectal atresia. Unsuitable neorectus position or striated muscle complex hypoplasia are causes of postoperative incontinence in these patients.

Anorectal motor disorders

Anorectal motor disorders such as faecal incontinence, chronic anorectal pain and solitary rectal ulcer syndrome are common in the community. They cause psychological distress, affect quality of life, and pose a significant economic burden. In recent years, many strides have been made in the diagnostic criteria and in the mechanistic understanding of anorectal disorders. The use of innovative manometric, neurophysiological and radiological techniques have shed new light on the underlying pathophysiology. Also, it has been recognised that psychological dysfunction play an important role. However, there is a lack of consensus regarding what is abnormal, regarding the overlap between phenotypes and regarding optimal diagnostic approaches or tests. There has been little advance in drug therapy for these conditions. Although several treatments have been tried and appear promising, controlled trials are either lacking or have provided insignificant evidence. There is a need for improved medical, behavioural and surgical treatments for these conditions.

The current role of imaging techniques in faecal incontinence

Faecal incontinence is a common multifactorial disorder. Major causes of faecal incontinence are related to vaginal delivery and prior anorectal surgery. In addition to medical history and physical examination, several anorectal functional tests and imaging techniques can be used to assess the underlying pathophysiology and to guide treatment planning in faecal incontinent patients. Anorectal functional tests provide functional information, but the potential strength comes from combining test results. Imaging techniques, including defecography, endoanal sonography, and magnetic resonance (MR) imaging, provide structural information about the anorectal region with a direct clinical impact. The major role of imaging techniques in faecal incontinence is visualising the structural and functional integrity of the anal sphincter complex. Both two-dimensional endoanal sonography and endoanal MR imaging are accurate tools to depict anal sphincter defects. The major advantage of endoanal MR imaging is the accurate demonstration of external anal sphincter atrophy. Recent studies have suggested that external phased array MR imaging and three-dimensional endoanal sonography are also valuable tools in the diagnostic work up of faecal incontinence. Decisions about the preferred technique will mainly be determined by availability and local expertise. This article demonstrates the current role of tests, predominantly imaging tests, in the diagnostic work up of faecal incontinence.