Endoanal Magnetic Resonance Imaging Research Articles

A comparison of trans-fistula contrast-enhanced endoanal ultrasound and MRI in the diagnosis of anal fistula.

Many hospitals favor magnetic resonance imaging (MRI) as the preferred diagnostic method to detect anal fistula, trans-fistula contrast-enhanced ultrasound (CEUS) for the diagnosis of anal fistula have attracted the attention of investigators worldwide. This study aimed to investigate the efficacy of trans-fistula contrast-enhanced endoanal ultrasound (CEUS) and magnetic resonance imaging (MRI) in the diagnosis of anal fistula. Ninety-eight patients undergoing trans-fistula CEUS and MRI were retrospectively analyzed. The fistulous trend and positional relation between the fistula, levator ani muscle, and sphincter (Parks classification), as well as the numbers of fistulous branches, number and position of the fistula, and distance between internal opening and anal edge were recorded. These parameters were compared with the postoperative results. There were no significant statistical differences (P>0.05) in the accuracy rates of trans-fistula CEUS and MRI, respectively, in terms of Parks classification (90.82%, 92.86%), branches (89.19%, 81.08%), internal openings (92.68%, 89.43%), and internal openings ≥3 cm from the anal edge (85.71%, 92.86%). However, we observed a significant difference in terms of internal openings <3 cm from the anal edge (96.30%, 87.65%) (P=0.043). Although both methods exhibited a perfect accuracy rate in diagnosing anal fistula, trans-fistula CEUS displayed superior diagnostic value for internal openings <3 cm from the anal edge, and could provide reliable pre-operative evidence.

Severe perineal hidradenitis suppurativa (HS) and anal fistulas. An underrated association?

Abstract Background Due to its multiple forms of debut hidradenitis suppurativa has classically been a diagnostic challenge as well in the differential diagnosis. Prevalence of perianal fistula in patients with hidradenitis suppurativa ranges form 6,6% to 67%. The aim of the study was to assess both conditions. Methods A retrospective chart review from 2000 to 2018 using the ICD-9-CM, coded with 705.83. for patients with hidradenitis suppurativa was conducted. Hurley’s three stage classification was applied. Diagnosis and relevant patient characteristics were assessed and the presence of associated perianal fistula. Endoa-nal ultrasound (EAU) was performed in 61% of the patients with perianal hidradenitis and perianal fistu-la, and magnetic resonance imaging (MRI) in 19%. Results Of 143 cases with hidradenitis, sixty two cases (43,4%) presented perianal (perineal/buttocks) location. Of them 93,5% were men. Twenty-one percent were associated with perianal fistulas being 6 of them complex ones associated with Hurley stage II and III. Treatment for the latter included: loose setons in 4 patients with Crohn’s disease and in 2 non Crohn’s disease with complex fistulas, 4 fistulotomies and 2 fistulectomies in low transphincteric fistulas and 1 with incision and drainage. Conclusion Perianal fistula should be treated according to associated diseases and type of fistula. Association of hidradenitis and perianal fistulas may be higher than expected and the relation of severe hidradenitis with complex perianal fistulas should be studied further. Endoanal ultrasound and MRI may be useful tools to assess HS with complex perianal fistulas, but the iconographic patterns of hidradenitis and Crohn’s disease should be kept in mind as both may be associated.

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

ObjectivesThe 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).MethodsForty 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.ResultsThere 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).ConclusionsThe 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.

Endoanal ultrasound in perianal fistulae and abscesses.

Endoanal ultrasound is a technique that provides imaging of the anal sphincters and its surrounding structures as well as the pelvic floor. However, endoanal magnetic resonance imaging (MRI) is preferred by most physicians, although costs are higher and demand easily outgrows availability. Endoanal ultrasound is an accurate imaging modality delineating anatomy of both cryptoglandular as well as Crohn perianal fistula and abscess. Endoanal ultrasound is comparable with examination under anesthesia and equally sensitive as endoanal MRI in fistula detection. When fistula tracts or abscesses are located above the puborectal muscle, an additional endoanal MRI should be performed. Preoperative imaging is advocated in recurrent cryptoglandular fistula because a more complex pattern can be expected. Endoanal ultrasound can help avoid missing tracts during surgery, lowering the chance for the fistula to persist or recur. It can easily be performed in an outpatient setting and endosonographic skills are quickly incremented. Costs are low and endoanal ultrasound has the potential to improve outcome of patients with both cryptoglandular and fistulizing Crohn disease; therefore, it values more attention.

Relationship Among Anal Sphincter Injury, Patulous Anal Canal, and Anal Pressures in Patients With Anorectal Disorders

The anal sphincters and puborectalis are imaged routinely with an endoanal magnetic resonance imaging (MRI) coil, which does not assess co-aptation of the anal canal at rest. By using a MRI torso coil, we identified a patulous anal canal in some patients with anorectal disorders. We aimed to evaluate the relationship between anal sphincter and puborectalis injury, a patulous anal canal, and anal pressures. We performed a retrospective analysis of data from 119 patients who underwent MRI and manometry analysis of anal anatomy and pressures, respectively, from February 2011 through March 2013 at the Mayo Clinic. Anal pressures were determined by high-resolution manometry, anal sphincter and puborectalis injury was determined by endoanal MRI, and anal canal integrity was determined by torso MRI. Associations between manometric and anatomic parameters were evaluated with univariate and multivariate analyses. Fecal incontinence (55 patients; 46%) and constipation (36 patients; 30%) were the main indications for testing; 49 patients (41%) had a patulous anal canal, which was associated with injury to more than 1 muscle (all P ≤ .001), and internal sphincter (P < .01), but not puborectalis (P = .09) or external sphincter (P = .06), injury. Internal (P < .01) and external sphincter injury (P = .02) and a patulous canal (P < .001), but not puborectalis injury, predicted anal resting pressure. A patulous anal canal was the only significant predictor (P < .01) of the anal squeeze pressure increment. Patients with anorectal disorders commonly have a patulous anal canal, which is associated with more severe anal injury and independently predicted anal resting pressure and squeeze pressure increment. It therefore is important to identify a patulous anal canal because it appears to be a marker of not only anal sphincter injury but disturbances beyond sphincter injury, such as damage to the anal cushions or anal denervation.

Endoanal ultrasonography in fecal incontinence: Current and future perspectives.

Fecal incontinence has a profound impact in a patient's life, impairing quality of life and carrying a substantial economic burden due to health costs. It is an underdiagnosed condition because many affected patients are reluctant to report it and also clinicians are usually not alert to it. Patient evaluation with a detailed clinical history and examination is very important to indicate the type of injury that is present. Endoanal ultrasonography is currently the gold standard for sphincter evaluation in fecal incontinence and is a simple, well-tolerated and non-expensive technique. Most studies revealed 100% sensitivity in identifying sphincter defect. It is better than endoanal magnetic resonance imaging for internal anal sphincter defects, equivalent for the diagnosis of external anal sphincter defects, but with a lower capacity for assessment of atrophy of this sphincter. The most common cause of fecal incontinence is anal sphincter injury related to obstetric trauma. Only a small percentage of women are diagnosed with sphincter tears immediately after vaginal delivery, but endoanal ultrasonography shows that one third of these women have occult sphincter defects. Furthermore, in patients submitted to primary repair of these tears, ultrasound revealed a high frequency of persistent sphincter defects after surgery. Three-dimensional endoanal ultrasonography is currently largely used and accepted for sphincter evaluation in fecal incontinence, improving diagnostic accuracy and our knowledge of physiologic and pathological sphincters alterations. Conversely, there is currently no evidence to support the use of elastography in fecal incontinence evaluation.

Effects of Clonidine in Women With Fecal Incontinence

Some women with urge-predominant fecal incontinence (FI) have diarrhea-predominant irritable bowel syndrome and a stiffer and hypersensitive rectum. We evaluated the effects of the α2-adrenergic agonist clonidine on symptoms and anorectal functions in women with FI in a prospective, placebo-controlled trial. We assessed bowel symptoms and anorectal functions (anal pressures, rectal compliance, and sensation) in 43 women (age, 58 ± 2 y) with urge-predominant FI, randomly assigned to groups given oral clonidine (0.1 mg, twice daily) or placebo for 4 weeks. Before and after administration of the medication, anal pressures were evaluated by manometry, and rectal compliance and sensation were measured using a barostat. Anal sphincter injury was evaluated by endoanal magnetic resonance imaging. Bowel symptoms were recorded in daily and weekly diaries. The primary end point was the FI and Constipation Assessment symptom severity score. FI scores decreased from 9.1 ± 0.3 to 7.6 ± 0.5 among subjects given placebo and from 8.1 ± 0.4 to 6.5 ± 0.6 among patients given clonidine. Clonidine did not affect FI symptom severity, bowel symptoms (stool consistency or frequency), anal pressures, rectal compliance, or sensation compared with placebo. However, when baseline data were used to categorize subjects as those with or without diarrhea, clonidine reduced the proportion of loose stools in patients with diarrhea only (P = .018). Clonidine also reduced the proportion of days with FI in patients with diarrhea (P = .0825). Overall, clonidine did not affect bowel symptoms, fecal continence, or anorectal functions, compared with placebo, in women with urge-predominant FI. Among patients with diarrhea, clonidine increased stool consistency, with a borderline significant improvement in fecal continence. ClinicalTrials.gov, Number NCT00884832.

Anal carcinomas: the role of endoanal ultrasound and magnetic resonance imaging in staging, response evaluation and follow-up

Anal carcinoma is an important but rare condition, managed in specialist centres. Both endoanal ultrasound and magnetic resonance imaging (MRI) can be used in the locoregional staging and follow-up of patients with anal cancer, and both may assist in treatment planning and prognosis. Recent guidelines published by the European Society for Medical Oncology have recommended MRI as the technique of choice for assessment of locoregional disease. This paper describes the techniques for both endoanal ultrasound and MRI, and compares the relative merits and disadvantages of each in the local assessment of anal carcinoma.

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

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). Studies on EAUS and EAMRI were selected and analyzed to generate summative data. 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. 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.

Magnetic Resonance Imaging in Fecal Incontinence

Fecal incontinence is a frequent condition. The workup of patients with fecal incontinence comprises clinical history, physical examination, anofunctional tests and imaging. In many institutions, imaging in these patients concerns endosonography. Magnetic resonance imaging (MRI) is a valuable alternative to endosonography. For detection of external sphincter defects the techniques have comparable results. However, visualization of the external sphincter at MRI is superior to endosonography, facilitating identification of external sphincter atrophy. External sphincter atrophy at MRI is related to poor outcome of anterior anal repair and therefore MRI should be considered in potential candidates for anterior anal repair. External coil MRI is a widely available alternative to endoanal MRI and can be used as an alternative in experienced hands.

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

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

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

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. 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. 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. 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.

Can the outcome of pelvic-floor rehabilitation in patients with fecal incontinence be predicted?

PurposePelvic-floor rehabilitation does not provide the same degree of relief in all fecal incontinent patients. We aimed at studying prospectively the ability of tests to predict the outcome of pelvic-floor rehabilitation in patients with fecal incontinence.Materials and methodsTwo hundred fifty consecutive patients (228 women) underwent medical history and a standardized series of tests, including physical examination, anal manometry, pudendal nerve latency testing, anal sensitivity testing, rectal capacity measurement, defecography, endoanal sonography, and endoanal magnetic resonance imaging. Subsequently, patients were referred for pelvic-floor rehabilitation. Outcome of pelvic-floor rehabilitation was quantified by the Vaizey incontinence score. Linear regression analyses were used to identify candidate predictors and to construct a multivariable prediction model for the posttreatment Vaizey score.ResultsAfter pelvic-floor rehabilitation, the mean baseline Vaizey score (18, SD ± 3) was reduced with 3.2 points (p < 0.001). In addition to the baseline Vaizey score, three elements from medical history were significantly associated with the posttreatment Vaizey score (presence of passive incontinence, thin stool consistency, primary repair of a rupture after vaginal delivery at childbed) (R2, 0.18). The predictive value was significantly but marginally improved by adding the following test results: perineal and/or perianal scar tissue (physical examination), and maximal squeeze pressure (anal manometry; R2, 0.20; p = 0.05).ConclusionAdditional tests have a limited role in predicting success of pelvic-floor rehabilitation in patients with fecal incontinence.

External Anal Sphincter Defects in Patients with Fecal Incontinence: Comparison of Endoanal MR Imaging and Endoanal US

To prospectively compare in a multicenter study the agreement between endoanal magnetic resonance (MR) imaging and endoanal ultrasonography (US) in depicting external anal sphincter (EAS) defects in patients with fecal incontinence. The study was approved by the medical ethics committee of all participating centers. A total of 237 consenting patients (214 women, 23 men; mean age, 58.6 years +/- 13 [standard deviation]) with fecal incontinence were examined from 13 different hospitals by using endoanal MR imaging and endoanal US. Patients with an anterior EAS defect depicted on endoanal MR images and/or endoanal US scans underwent anal sphincter repair. Surgical findings were used as the reference standard in the determination of anterior EAS defects. The Cohen kappa statistic and McNemar test were used to calculate agreement and differences between diagnostic techniques. Agreement between endoanal MR imaging and endoanal US was fair for the depiction of sphincter defects (kappa = 0.24 [95% confidence interval: 0.12, 0.36]). At surgery, EAS defects were found in 31 (86%) of 36 patients. There was no significant difference between MR imaging and US in the depiction of sphincter defects (P = .23). Sensitivity and positive predictive value were 81% and 89%, respectively, for endoanal MR imaging and 90% and 85%, respectively, for endoanal US. In the selection of patients for anal sphincter repair, both endoanal MR imaging and endoanal US are sensitive tools for preoperative assessment, and both techniques can be used to depict surgically repairable anterior EAS defects.

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

Objectives: Anal sphincter atrophy is associated with a poor clinical outcome of sphincter repair in patients with faecal incontinence. Preoperative assessment of the sphincter 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 this study was to establish whether 3D EUS measurements can be used to detect EAS atrophy. For this purpose 3D EUS measurements were compared to endoanal MRI measurements.

Accuracy and patient preference in evaluating perianal fistulas using hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging

Objectives: Surgery for perianal fistula is often complicated and therefore accurate preoperative assessment of perianal fistulas is necessary. The aim of this study was to determine agreement between hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography (3D HPUS) and endoanal magnetic resonance imaging (MRI) in preoperative assessment of perianal fistulas and to assess patient preference with regard to these techniques.

Accuracy and patient preference in evaluating perianal fistulas using hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging

Accuracy and patient preference in evaluating perianal fistulas using hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging

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

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. 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. 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. 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.

Endosonography in anorectal disease: An overview

Anorectal endosonography (AE), which was introduced 20 years ago, derives from the study of urology. It was first used to evaluate rectal tumours and later also to investigate benign disorders of the anal sphincters and pelvic floor. The technique is easy to perform, it has a short learning curve and causes no more discomfort than a routine digital examination. A rotating probe with a 360° radius and a frequency between 5 and 16 MHz is introduced to the rectum and then slowly withdrawn so that the pelvic floor and subsequently the sphincter complex are seen. Recently, it has become possible to reconstruct three-dimensional images. AE has been used for almost every possible disorder in the anal region and has increased our insight into anal pathology. The clinical indications for AE are: 1. Faecal incontinence in patients when surgery is an option. AE can show sphincter defects with excellent precision. There is a perfect correlation with surgical findings. Studies comparing AE with endoanal magnetic resonance imaging (MRI) have shown that both methods are equally good for demonstrating defects in the external anal sphincter; the internal anal sphincter is better visualized with AE. After sphincter repair, the effect is directly related to the decrease in the sphincter defect. 2. Perianal fistulae. AE has been shown to be accurate in staging perianal cryptoglandular fistulae and fistulae in Crohn's disease. When there is an external fistula opening, H2O2 can be introduced with a plastic infusion catheter. The tract then becomes visible as a hyperechoic lesion (“white”). It has been shown that this corresponds well with surgical findings. It is equally sensitive as endoanal MRI. Since recurrent cryptoglandular fistulae are complex in 50% and Crohn's fistula in 75%, it is mandatory to perform AE preoperatively in these patients to avoid missed tracts during surgery and subsequent recurrences. 3. Rectal tumors. In low tubulovillous adenomas or malignant polyps considered removable locally, confirming the local resectability (T0 or T1) is mandatory. Although larger rectal and more advanced tumours can be evaluated with AE, MRI is more sensitive in staging nodal involvement. 4. Anal carcinoma for staging. AE has been shown to stage better than the classical TNM classification for both local extension and prognosis. In conclusion, AE images the internal and external anal sphincter with high accuracy. It is easy to perform and is of particular value in the diagnosis of anal incontinence and perianal fistulae. It is excellent in staging anal carcinoma and can also be used in staging rectal carcinoma, especially very low large malignant polyps.