Endocoil magnetic resonance imaging quantification of external anal sphincter atrophy

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.

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.

Clinical applications of pelvic floor imaging: opinion statement endorsed by the society of abdominal radiology (SAR), American Urological Association (AUA), and American Urogynecologic Society (AUGS)

Pelvic floor dysfunction is prevalent, with multifactorial causes and variable clinical presentations. Accurate diagnosis and assessment of the involved structures commonly requires a multidisciplinary approach. Imaging is often complementary to clinical assessment, and the most commonly used modalities for pelvic floor imaging include fluoroscopic defecography, magnetic resonance defecography, and pelvic floor ultrasound. This collaboration opinion paper was developed by representatives from multiple specialties involved in care of patients with pelvic floor dysfunction (radiologists, urogynecologists, urologists, and colorectal surgeons). Here, we discuss the utility of imaging techniques in various clinical scenarios, highlighting the perspectives of referring physicians. The final draft was endorsed by the Society of Abdominal Radiology (SAR), American Urogynecologic Society (AUGS), and the American Urological Association (AUA).

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.

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.

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.

Critical reappraisal of anorectal function tests in patients with faecal incontinence who have failed conservative treatment

OBJECTIVE

Anorectal function tests are often performed in patients with faecal incontinence who have failed conservative treatment. This study was aimed to establish the additive value of performing anorectal function tests in these patients in selecting them for surgery.

PATIENTS AND METHODS

Between 2003 and 2009, all referred patients with faecal incontinence were assessed by a questionnaire, anorectal manometry and anal endosonography. Patients with diarrhea, inflammatory bowel disease, pouches or rectal carcinoma were excluded.

RESULTS

In total, 218 patients were evaluated. Of these, 107 (49%) patients had no sphincter defects, 71 (33%) had small defects and 40 (18%) had large defects. Anorectal manometry could not differentiate between patients with and without sphincter defects. Patients with sphincter defects were only found to have a significantly shorter sphincter length and reduced rectal capacity compared to patients without sphincter defects. Forty-three patients (20%) had a normal anal pressures ≥ 40 mmHg. Seventeen patients (8%) had also a dyssynergic pelvic floor both on clinical examination and anorectal manometry. Fifteen patients (7%) had a reduced rectal capacity between 65 and 100 ml. There was no difference in anal pressures or the presence of sphincter defects in these patients compared to patients with a rectal capacity >150 ml. There was no correlation between anorectal manometry, endosonography and faecal incontinence severity scores.

CONCLUSION

In patients with faecal incontinence who have failed conservative treatment, only anal endosonography can reveal sphincter defects. Anorectal manometry should be reserved for patients eligible for surgery to exclude those with suspected dyssynergic floor or reduced rectal capacity.

Functional imaging of the pelvic floor

The clinical treatment of patients with anorectal and pelvic floor dysfunction is often difficult. Dynamic cystocolpoproctography (DCP) has evolved from a method of evaluating the anorectum for functional disorders to its current status as a functional method of evaluating the global pelvic floor for defecatory disorders and pelvic organ prolapse. It has both high observer accuracy and a high yield of positive diagnoses. Clinicians find it a useful diagnostic tool that can alter management decisions from surgical to medical and vice versa in many cases. Functional radiography provides the maximum stress to the pelvic floor, resulting in levator ani relaxation accompanied by rectal emptying-which is needed to diagnose defecatory disorders. It also provides organ-specific quantificative information about female pelvic organ prolapse-information that usually can only be inferred by means of physical examination. The application of functional radiography to the assessment of defecatory disorders and pelvic organ prolapse has highlighted the limitations of physical examination. It has become clear that pelvic floor disorders rarely occur in isolation and that global pelvic floor assessment is necessary. Despite the advances in other imaging methods, DCP has remained a practical, cost-effective procedure for the evaluation of anorectal and pelvic floor dysfunction. In this article, the authors describe the technique they use when performing DCP, define the radiographic criteria used for diagnosis, and discuss the limitations and clinical utility of DCP.

Long-term effects on pressure and electromyography in a rat model of anal sphincter injury

PURPOSE

The goal of this research was to study the chronic effects of pudendal nerve transection and sphincterotomy on the anal sphincter, because there is no good animal model investigating anal sphincter injury. Clinically, anal sphincter dysfunction impacts a cohort of women who have fecal incontinence; conclusions from the study can benefit research for new effective treatments.

METHODS

Sixty-eight virgin Sprague-Dawley rats were allocated into control (n = 12), sphincterotomy (n = 28), and pudendal nerve transection (n = 28) groups and were evaluated before injury and immediately, 4 days, 14 days, and 28 days after. Anal pressures and electromyography were recorded and statistically compared. The anal sphincter was submitted to histology.

RESULTS

: Sphincterotomy data showed anal pressure recovery 14 days after injury and were comparable to controls after 28 days. Pudendal nerve transection showed a significant decrease in anal pressure 4 days after injury (P < .001), and this continued until 28 days after injury (P = .01). Electromyography showed significant loss of activity after nerve transection compared with controls. Twenty-eight days after sphincterotomy and nerve transection, fibrosis and muscle atrophy of the external anal sphincter muscle were demonstrated, respectively.

CONCLUSION

Anal pressures recover significantly after sphincterotomy. Pudendal nerve transection caused atrophy of the external anal sphincter that was reflected by decreased pressures and electromyography. The results of this study can contribute to a better understanding of the mechanisms that lead to fecal incontinence and can be used to test the efficacy of therapies.

Assessment of sonographic quality of anal sphincter muscles in patients with faecal incontinence

OBJECTIVE

The main application of endoanal ultrasonography (US) in evaluation of faecal incontinence is to identify surgically correctable sphincter defects. The aim of our study was to determine whether qualitative changes in echogenicity and in uniformity of internal (IAS) and external (EAS) anal sphincter muscles detected on endoanal US correlate with other anal laboratory tests and modified Wexner faecal incontinence functional score.

METHOD

Records on 99 patients having complete information on anorectal manometry, faecal incontinence scoring and available endoanal US imaging of the anal sphincters were included in statistical analysis. Anatomic appearance and changes in echogenicity of the anal sphincter muscles were recorded according to the proposed scoring system. Endoanal US defect and quality component scores for IAS and EAS as well as the total score were correlated with anal laboratory tests and incontinence score using Spearman's correlations test.

RESULTS

There was a trend for correlation between IAS quality score and incontinence score (P = 0.06), but no correlation for IAS defect score. EAS defect score had a significant negative correlation with maximum squeeze pressure (MSP) (P = 0.031). Distal EAS quality score had a significant correlation with incontinence score (P = 0.002). EAS total score correlated with MSP (P = 0.02) and incontinence score (P = 0.006). Endoanal US total score was significantly correlated with incontinence score (P = 0.006), maximal resting (MRP) (P = 0.035) and MSP (P = 0.045) and high pressure anal canal zone length (P = 0.03).

CONCLUSION

Sonographic morphology of anal sphincter muscles correlates with anal laboratory tests and functional incontinence score. Qualitative ultrasound scoring instrument may improve evaluation of patients with faecal incontinence.

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.

Effects of age and gender on three-dimensional endoanal ultrasonography measurements: development of normal ranges

BACKGROUND

Faecal incontinence is a common and morbid disorder that is often related to anal sphincter dysfunction. High-frequency, three-dimensional (3-D) endoanal ultrasonography (EAUS) allows greater spatial resolution and longitudinal appreciation of the anal canal than conventional 2-D assessment. A robust normal range of values allowing for age and sex is required for subsequent disease comparison.

METHODS

A group of 30 healthy male (n=12) and female (n=18) volunteers (median age, 49 years; range, 31-63 years) underwent 3-D EAUS using a high-frequency 10-MHz transducer. A reconstructed data cube was interrogated to measure anal canal structures in 2-D at high, middle and low levels, and in 3-D for longitudinal measurements.

RESULTS

Men had a significantly longer 3-D external anal sphincter (EAS) and internal anal sphincter (IAS) than women, especially the anterior EAS (mean in men 2.5 cm, mean in women 1.6 cm, p<0.0001). There were no significant differences between the sexes for anal canal length or by 2-D scanning for the thickness of the EAS and IAS. No significant differences were observed between parous and nulliparous women. Age had no significant effect on 3-D length measurements, but 2-D EAUS measurements of the thickness of both the IAS and EAS increased with age significantly (mid canal, p=0.004). On these bases, normal ranges were generated.

CONCLUSIONS

Sphincter measurements, enabled by 3-D reconstruction, vary with age and sex. A normal range incorporating these variations has been produced for future data comparison in disease states.

Endoanal ultrasound in benign anorectal disorders: clinical relevance and possibilities

Endoanal ultrasound is a well-established technique used to evaluate benign anorectal disorders. The technique is easy to perform, has a short learning curve and causes very little discomfort. Reconstruction of 3D images is possible. The clinical indications for endoanal ultrasound in benign anorectal diseases are fecal incontinence and peri-anal fistula. Sphincter defects can be depicted with precision and correlate perfectly with surgical findings. Furthermore, an impression of sphincter atrophy can be established. With perianal fistula the tracts can be visualized. Introducing hydrogen peroxide via the external fistula opening improves imaging. Endoanal ultrasound and MRI have comparable results in diagnosing anorectal disorders.

The role of three-dimensional endoluminal ultrasound imaging in the evaluation of anorectal diseases: a review

BACKGROUND

The authors conducted a review of the available English literature to evaluate the advantages of three-dimensional ultrasound for assessing anorectal pathology, to provide a state-of-the-art approach, and to compare this technique with conventional endoluminal ultrasound and other imaging methods.

METHODS

All studies describing results obtained with three-dimensional ultrasound in the evaluation of anorectal pathologies, both alone and compared with other techniques, were selected.

RESULTS

Since 1996, 32 articles have been published. In tumor staging, specific data derived by three-dimensional reconstruction for the assessment of T invasion and nodal involvement were more accurate than endoluminal ultrasound and computed tomography. For evaluating perianal sepsis, the detection of secondary fistula tracts and fluid collections and the location of internal openings were superior to endoanal magnetic resonance imaging. In the evaluation of anal incontinence, the results for sphincter defects were similar to those obtained with endoanal magnetic resonance imaging.

CONCLUSION

Analysis of the literature confirmed that three-dimensional ultrasound is a valuable technique for assessing anorectal disorders, facilitating the interpretation of the images obtained, and providing additional data that in many cases have changed the operative approach.

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.

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

OBJECTIVE

External anal sphincter atrophy seen at endoanal MRI may predict poor outcome of surgical anal sphincter repair for an external anal sphincter defect. The purposes of this study were to compare external phased-array MRI to endoanal MRI for depicting external anal sphincter atrophy in patients with fecal incontinence and to evaluate observer reproducibility in detecting external anal sphincter atrophy with these techniques.

SUBJECTS AND METHODS

Thirty patients with fecal incontinence (23 women, seven men; mean age, 58.7 years; age range, 37-78 years) underwent both endoanal and external phased-array MRI. Images were evaluated for external anal sphincter atrophy by three radiologists. Measures of differences and agreement between both MRI techniques and of interobserver and intraobserver agreement of both techniques were calculated.

RESULTS

The MRI techniques did not significantly differ in their ability to depict external anal sphincter atrophy (p = 0.63) with good agreement (kappa = 0.72). Interobserver agreement was moderate (kappa = 0.53-0.56) for endoanal MRI and moderate to good (kappa = 0.55-0.8) for external phased-array MRI. Intraobserver agreement was moderate to very good (kappa = 0.57-0.86) for endoanal MRI and fair to very good (kappa = 0.31-0.86) for external phased-array MRI.

CONCLUSION

External phased-array MRI is comparable to endoanal MRI in depicting external anal sphincter atrophy and, thereby, in selecting patients for anal sphincter repair. Because results among interpreters varied considerably depending on the experience level, both techniques can be recommended in the diagnostic workup of fecal incontinence only if sufficient experience is available.

Magnetic resonance imaging measurement of the anorectal striated muscle complex in normal children

PURPOSE

The aim of the study was to describe and establish a normal measurement of the striated muscle complex (SMC) in healthy children using body phased-array or head coil magnetic resonance imaging.

METHODS

Imaging was performed in 20 boys and 20 girls (age range, from 3 months to 14 years; average age, 3.2 years) without anorectal disorders. The dimensions of the puborectalis muscle (PR) and external anal sphincter (EAS) were measured in different planes.

RESULTS

There was a close positive correlation between absolute width and length of SMC and age (P < .05), whereas there was no correlation between the relative width and length of SMC and age (P > .05). Normal relative length of the PR and EAS were measured as 0.47 +/- 0.04 and 0.41 +/- 0.04, respectively, and the normal relative width of PR and posterior EAS were 0.50 +/- 0.04 and 0.44 +/- 0.04 in children younger than 14 years.

CONCLUSIONS

The width and length of PR and EAS increase progressively with age. The relative width and length of PR and EAS were not variable with age. A relative width and length of PR and EAS were chosen as objective criteria for normal SMC in children younger than 14 years.

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.

Relationship between external anal sphincter atrophy at endoanal magnetic resonance imaging and clinical, functional, and anatomic characteristics in patients with fecal incontinence

PURPOSE

External anal sphincter atrophy at endoanal magnetic resonance imaging has been associated with poor outcome of anal sphincter repair. We studied the relationship between external anal sphincter atrophy on endoanal magnetic resonance imaging and clinical, functional, and anatomic characteristics in patients with fecal incontinence.

METHODS

In 200 patients (mean Vaizey score, 18 (+/-2.9 standard deviation)) magnetic resonance images were evaluated for external anal sphincter atrophy (none, mild, or severe) by radiologists blinded to anorectal functional test results and details from medical history. Subgroups of patients with and without atrophy were compared for medical history, anal manometry, pudendal nerve latency testing, anal sensitivity testing, external anal sphincter thickness, and external anal sphincter defects. Whenever significant differences were detected, we tested for differences between patients with mild and severe atrophy.

RESULTS

External anal sphincter atrophy was demonstrated in 123 patients (62 percent): graded as mild in 79 (40 percent), and severe in 44 patients (22 percent). Patients with atrophy were more often female (P < 0.001) and older (P = 0.003). They had a lower maximal squeeze (P = 0.01) and squeeze increment pressure (P < 0.001). Patients with severe atrophy had a lower maximal squeeze (P = 0.003) and squeeze increment pressure (P < 0.001) than patients with mild atrophy. These effects were not attenuated by potential confounding variables. Patients with atrophy could not be identified a priori by other characteristics.

CONCLUSIONS

External anal sphincter atrophy at endoanal magnetic resonance imaging was depicted in 62 percent of patients, varying from mild to severe. Because increasing levels of atrophy were associated with impaired squeeze function, further studies are needed to evaluate whether grading atrophy is clinically valuable in selecting patients for anal sphincter repair.

Endosonographic imaging of anorectal diseases

OBJECTIVE

The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography compared with magnetic resonance imaging are reviewed. Methods. Endosonographic imaging was performed with a Siemens (Erlangen, Germany) FI 400 ultrasound scanner with an end-fire 7.5-MHz biplane endorectal probe and a B-K Medical (Sandhoften, Denmark) scanner with an 1850 axial-type side-fire 5.0- to 10.0-MHz rotating endoscopic probe.

RESULTS

Rectal carcinoma appears on endorectal sonography as a low-echogenicity lesion that abruptly interrupts the normal sequence of layers. The internal anal sphincter is seen very clearly on endoanal sonography, and it is easy to appreciate atrophy and small tears of this sphincter. Endoanal sonography cannot accurately show thinning of the external anal sphincter. Peroxide-enhanced endoanal sonography is especially useful for patients with recurrent perianal fistulas in whom scarring should be distinguished from recurrent fistulas and detection of the internal opening. However, sonography does not provide an adequate deep and global display of all adjacent pelvic and perineal spaces.

CONCLUSIONS

Endosonography can accurately stage primary rectal tumors and assess the internal anal sphincter. Peroxide-enhanced 3-dimensional imaging can increase the utility of endoanal sonography in detection and characterization of perianal fistulas and planning of optimal therapy. However, magnetic resonance imaging can be used a complementary modality to endosonography, especially for evaluation of external anal sphincter atrophy and deep pelvic inflammation.

Atrophy and defects detection of the external anal sphincter: comparison between three-dimensional anal endosonography and endoanal magnetic resonance imaging

PURPOSE

Using endoanal magnetic resonance imaging, atrophy of the external anal sphincter can be established. This aspect has not been thoroughly investigated using three-dimensional anal endosonography. The purpose of this study was to compare prospectively three-dimensional anal endosonography to magnetic resonance imaging in the detection of atrophy and defects of the external anal sphincter in patients with fecal incontinence. In addition, we compared both techniques for anal sphincter thickness and length measurements.

MATERIALS AND METHODS

Patients with fecal incontinence underwent three-dimensional anal endosonography and magnetic resonance imaging. Images of both endoluminal techniques were evaluated for atrophy and defects of the external anal sphincter. External anal sphincter atrophy scoring with three-dimensional anal endosonography depended on the distinction of the external anal sphincter and its reflectivity. External anal sphincter atrophy scoring with magnetic resonance imaging depended on the amount of muscle and the presence of fat replacement. Atrophy score was defined as none, moderate, and severe. A defect was defined at anal endosonography by a hypoechogenic zone and at magnetic resonance imaging as a discontinuity of the sphincteric ring and/or scar tissue. Differences between three-dimensional anal endosonography and magnetic resonance imaging for the detection of external anal sphincter atrophy and defects were calculated. In addition, we compared external anal sphincter thickness and length measurements in three-dimensional anal endosonography and magnetic resonance imaging.

RESULTS

Eighteen patients were included (median age, 58 years; range, 27-80; 15 women). Three-dimensional anal endosonography and magnetic resonance imaging did not significantly differ for the detection of external anal sphincter atrophy (P = 0.25) and defects (P = 0.38). Three-dimensional anal endosonography demonstrated atrophy in 16 patients, magnetic resonance imaging detected atrophy in 13 patients. Three-dimensional anal endosonography agreed with magnetic resonance imaging in 15 of 18 patients for the detection of external anal sphincter atrophy. Using the grading system, 8 of the 18 patients scored the same grade. Three-dimensional anal endosonography detected seven external anal sphincter defects and magnetic resonance imaging detected ten. Three-dimensional anal endosonography and magnetic resonance imaging agreed on the detection of external anal sphincter defects in 13 of 18 patients. Comparison between three-dimensional anal endosonography and magnetic resonance imaging for sphincter thickness and length measurements showed no statistically significant concordance and had no correlation with external anal sphincter atrophy.

CONCLUSION

This is the first study that shows that three-dimensional anal endosonography can be used for detecting external anal sphincter atrophy. Both endoanal techniques are comparable in detecting atrophy and defects of the external anal sphincter, although there is a substantial difference in grading of external anal sphincter atrophy. Correlation between three-dimensional anal endosonography and magnetic resonance imaging for thickness and length measurements is poor. Inconsistency between the two methods needs to be evaluated further.

Can three-dimensional endoanal ultrasonography detect external anal sphincter atrophy? A comparison with endoanal magnetic resonance imaging

PURPOSE

Anal sphincter atrophy is associated with a poor clinical outcome of sphincter repair in patients with faecal incontinence. Preoperative assessment of the sphincters is therefore relevant. External anal sphincter (EAS) atrophy can be detected by endoanal magnetic resonance imaging (MRI), but not by conventional endoanal ultrasonography (EUS). Three-dimensional EUS allows multiplanar imaging of the anal sphincters and thus enables more reliable anal sphincter measurements. The aim of the present study was to establish whether 3D EUS measurements can be used to detect EAS atrophy. For this purpose 3D EUS measurements were compared with endoanal MRI measurements.

METHODS

Patients with symptoms of faecal incontinence underwent 3D EUS and endoanal MRI. Internal anal sphincter (IAS) and EAS defects were assessed on 3D EUS and endoanal MRI. EAS atrophy was determined on endoanal MRI. The following measurements were performed: EAS length, thickness and area. Furthermore, EAS volume was determined on 3D EUS and compared with EAS thickness and area measured on endoanal MRI.

RESULTS

Eighteen parous women (median age 56 years, range 32-80) with symptoms of faecal incontinence were included. Agreement between 3D EUS and endoanal MRI was 61% for IAS defects and 88% for EAS defects. EAS atrophy was seen in all patients on endoanal MRI. Correlation between the two methods for EAS thickness, length and area was poor. In addition, correlation was also poor for EAS volume determined on 3D EUS, and EAS thickness and area measured on endoanal MRI.

CONCLUSION

Three-dimensional EUS and endoanal MRI are comparable for detecting EAS defects. However, correlation between the two methods for EAS thickness, length and area is poor. This is also the case for EAS volume determined on 3D EUS and EAS thickness and area measured on endoanal MRI. Three-dimensional EUS can be used for detecting EAS defects, but no 3D EUS measurements are suitable parameters for assessing EAS atrophy.

Volume measurements of the anal sphincter complex in healthy controls and fecal-incontinent patients with a three-dimensional reconstruction of endoanal ultrasonography images

OBJECTIVES

The aim of this study was to determine sphincter volume, length, and external anal sphincter thickness in healthy controls and fecal incontinent patients by use of a three-dimensional reconstruction of endoanal ultrasonography images.

METHODS

Forty-four controls (15 males, 15 females, and 14 parous females) and 28 incontinent parous females (with and without a sphincter defect) were studied. Internal anal sphincter, external anal sphincter and puborectalis volume, sphincter length, and external anal sphincter thickness were measured. Intraobserver and interobserver variability were assessed. Anal pressure profile was also determined.

RESULTS

Internal anal sphincter and external anal sphincter volumes were larger in males than in females (P = 0.001 and P = 0.04), and external anal sphincter volume was smaller in parous females but this was not significant (P = 0.084). Anterior sphincter length was longer in males (P = 0.004) and shorter in parous females (P = 0.06). Males had a larger anterior external anal sphincter thickness (P = 0.018); parity made no difference. Sphincter volumes were not smaller in incontinent females. Incontinent females with a sphincter defect had a shorter anterior sphincter length than that of continent (P = 0.001) and incontinent females without a sphincter defect (P < 0.001). Anterior external anal sphincter thickness was smaller in incontinent females with a sphincter defect (P = 0.006), and posterior and right external anal sphincter thickness was smaller in incontinent females without a sphincter defect (P = 0.02 and P = 0.03). Intraobserver variability was seen for internal anal sphincter volume and sphincter length, but there was no interobserver variability. Correlation between anal pressures and endoanal ultrasonography measurements was poor.

CONCLUSIONS

Differences in anal sphincter volumes are seen for gender but not for parity. Fecal incontinence is not associated with loss of sphincter volume. However, anterior sphincter length and external anal sphincter thickness are smaller.

Anal endosonography and its role in assessing the incontinent patient

Anal endosonography is now recognized as an important investigation in the assessment of faecal incontinence. The endosonographer needs to be aware that the anatomy of the anal sphincter is complex and therefore there can be pitfalls in the interpretation of images. The findings have clinical implications on subsequent management and can contribute to prognosticating outcome. However, anal endosonography has a complementary role and other investigations, such as anal manometry, should be performed before intervention.

Imaging fecal incontinence

Fecal incontinence is the inability to defer release of gas or stool from the anus and rectum by mechanisms of voluntary control. It is an important medical disorder affecting the quality of life of up to 20% of the population above 65 years. The most common contributing factors include previous vaginal deliveries, pelvic or perineal trauma, previous anorectal surgery, and rectal prolapse. Many physicians lack experience and knowledge related to pelvic floor incontinence disorders, but advancing technology has improved this knowledge. Increased experience with endoanal ultrasound and endoanal magnetic resonance imaging have given us a better understanding not only of the anatomy of the anal canal but also of the underlying morphological defects in fecal incontinence. Current imaging methods are emphasized and recent literature is reviewed.

Female anal sphincter: age-related differences in asymptomatic volunteers with high-frequency endoanal US

PURPOSE

To evaluate endoanal ultrasonographic (US) anatomy in a large group of nulliparous women by using a high-frequency 10-MHz transducer to define normal age-related differences in sphincter morphology.

MATERIALS AND METHODS

One hundred fifty asymptomatic nulliparous women (mean age, 31 years; range, 19-80 years) underwent endoanal US with a high-frequency 10-MHz transducer. Anal canal structures were measured at high, middle, and low levels and were correlated with age by using the Pearson simple linear correlation coefficient.

RESULTS

Internal sphincter thickness showed a highly significant positive correlation with age at both sites at which it was measured (high anal canal, r = 0.34, P <.001; middle anal canal, r = 0.33, P <.001). External sphincter thickness showed a highly significant negative correlation with age at all sites measured (high anal canal, r = -0.65, P <.001; middle anal canal, r = -0.49, P <.001; low anal canal, r = -0.21, P =.012). There was no significant correlation between age and thickness of subepithelial tissue, longitudinal muscle, or puborectalis muscle. Subjects whose internal sphincter showed mixed echogenicity were significantly older than those whose internal sphincter was uniformly hypoechoic (mean, 47.4 vs 34.6 years; P <.001). Subjects with mixed internal sphincter echogenicity also had a significantly thinner external sphincter at high (mean thickness, 3.8 vs 4.6 mm; P <.001) and middle (mean thickness, 3.7 vs 4.1 mm; P =.03) anal canal levels.

CONCLUSION

At older ages there are increased internal anal sphincter thickness and decreased external anal sphincter thickness. Diagnosis of external sphincter atrophy on the basis of sphincter thinning requires that one distinguish between abnormal thinning and age-related differences.