Endoscopic ultrasonography versus computed tomography in the differential diagnosis of perianorectal complications in Crohn's disease

Pre-operative assessment of anal fistulas using endoanal ultrasound

OBJECTIVE

To study the accuracy of endoanal ultrasound in pre-operative assessment of cryptoglandular anal fistulas, with respect to the site of the internal opening, type and depth of the fistula tract.

PATIENTS AND METHODS

A consecutive series of 151 patients with anal sepsis underwent pre-operative endoanal ultrasound assessment of a suspected anal fistula. Hydrogen peroxide was used to define the tract when there was doubt as to the course of the fistula. All patients subsequently had surgical exploration under anaesthesia, irrespective of findings at sonography. The site of the internal opening, depth and type of fistula were recorded at surgery, and concordance with the ultrasound was assessed.

RESULTS

One hundred and forty-five patients were subsequently shown to have a fistula at surgical exploration. Type of fistula: Two thirds were transsphincteric (63%) and one third were inter sphincteric (32%), with a few submucosal, and supra sphincteric fistulas. Ultrasound correctly predicted surgical findings in 82% of patients (124/151). Concordance was highest for transsphincteric fistulas (87%). Internal opening: Accuracy of predicting the site of the internal opening was 93% (140/151). The commonest site for the internal opening was the midline posteriorly (49%), followed by the midline anteriorly (25%), the rest lay laterally. Fistula depth: Ultrasound and surgical assessment of the depth of fistulas was concordant in 120 of 145 patients (83%).

CONCLUSIONS

Endoanal ultrasound has a high accuracy of predicting the site of internal opening of an anal fistula. Endoanal ultrasound is able to assess the type and depth of a fistula. This information is useful for pre-operative planning of fistula treatment.

The role of endoscopic ultrasound in inflammatory bowel disease

Ultrasonography has been applied to the diagnosis and management of inflammatory bowel disease for over 20 years. The combination of endoscopy with ultrasound has resulted in the application of intraluminal sonographic imaging to multiple diseases, including inflammatory bowel disease. Initial efforts were focused on the sonographic assessment of disease severity as based on bowel wall thickness, but this has been inconsistently demonstrated. Furthermore, disease severity is a clinical assessment that is based on both clinical and imaging studies. Recognizing that Crohn's disease tends to be transmural and ulcerative colitis a superficial mucosal inflammatory process, hopes were raised that endosonography would be effective in discriminating cases of otherwise indeterminate colitis. Efforts to demonstrate this, however, have been largely disappointing, and EUS plays a limited role in discriminating ulcerative colitis from Crohn's disease. On a more positive note, EUS evaluation of perirectal and perianal complications of Crohn's disease has been demonstrated to be superior to fistulography, CT, and equal to or superior to MRI. Because accurate anatomic information is required to guide surgical therapy of these lesions, EUS has the potential to emerge as a powerful imaging tool in the management of perianorectal Crohn's disease.

Endosonography of anal canal diseases

Anal endosonography became a valuable imaging method for diagnosis of anal diseases because of its accessibility, relative simplicity of performance, and low cost. It is used most often to detect anal sphincter defects, to classify anal fistulas and perianal abscesses, and to stage anal tumors. This review presents a normal anatomy of the anal canal, examination technique, and normal endosonographic anatomy of anal sphincters. The endosonographic findings of anal sepsis, malignancy, trauma, abnormalities in Crohn disease, and ulcerative colitis, as well as the role for anal endosonography among other imaging modalities, are discussed.

Endoscopy in inflammatory bowel disease

With the heterogeneous clinical presentation of IBD, endoscopy plays an integral role in the initial diagnosis of ulcerative colitis and Crohn's disease. Although radiographic tests often are supplemental in the work-up of IBD, colonoscopy with biopsy is the test of choice if IBD is suspected and is more sensitive than radiographic tests. Endoscopic features can be helpful in differentiating ulcerative colitis and Crohn's disease. Currently the only mode for detecting dysplasia and stratifying the risk of developing colorectal cancer is through complete colonoscopy with multiple biopsy specimens. Complications of IBD can be managed effectively with endoscopic therapy. The role of endoscopic ultrasound and future developments in endoscopic therapy need to be defined by future studies.

A comparison of endoscopic ultrasound, magnetic resonance imaging, and exam under anesthesia for evaluation of Crohn's perianal fistulas

BACKGROUND & AIMS

To determine accuracy of endoscopic ultrasound (EUS) and magnetic resonance imaging (MRI) for evaluation of Crohn's disease perianal fistulas.

METHODS

Thirty-four patients with suspected Crohn's disease perianal fistulas were prospectively enrolled in a blinded study comparing EUS, MRI, and examination under anesthesia (EUA). Fistulas were classified according to Parks' criteria, and a consensus gold standard was determined for each patient. Acceptable accuracy was defined as agreement with the consensus gold standard for > or =85% of patients.

RESULTS

Three patients did not undergo MRI; 1 did not undergo EUS or EUA; and consensus could not be reached for 1. Thirty-two patients had 39 fistulas (20 trans-sphincteric, 5 extra-sphincteric, 6 recto-vaginal, 8 others) and 13 abscesses. The accuracy of all 3 modalities was > or =85%: EUS 29 of 32 (91%, confidence interval [CI] 75%-98%), MRI 26 of 30 (87%, CI 69%-96%), and EUA 29 of 32 (91%, CI 75%-98%). Accuracy was 100% when any 2 tests were combined.

CONCLUSIONS

EUS, MRI, and EUA are accurate tests for determining fistula anatomy in patients with perianal Crohn's disease. The optimal approach may be combining any 2 of the 3 methods.

How can the assessment of fistula-inano be improved?

PURPOSE

Fistula-in-ano anatomy and its relationship with anal sphincters are important factors influencing the results of surgical management. Preoperative definition of fistulous track(s) and the internal opening play a primary role in minimizing iatrogenic damage to the sphincters and recurrence of the fistula.

METHODS

Physical examination and endoanal ultrasound (performed with a 10 MHz endoprobe), either conventionally or with an injection of hydrogen peroxide, were performed in 26 consecutive patients. Results were matched with surgical features to establish their accuracy in preoperative fistula-in-ano assessment.

RESULTS

Accuracy rates of clinical examination endoanal ultrasound, and hydrogen peroxide-enhanced ultrasound were 65.4, 50, and 76.9 percent for primary tracks, 73.1, 65.4, and 88.5 percent for secondary tracks, and 80.8, 80.8, and 92.3 percent for horseshoe extensions, respectively. Compared with physical examination and endoanal ultrasound, accuracy of hydrogen peroxide-enhanced ultrasound was higher for transsphincteric and intersphincteric primary tracks and horseshoe extensions. Both endoanal ultrasound and hydrogen peroxide-enhanced ultrasound displayed a significantly higher accuracy in detecting the internal openings (53.8 and 53.8 percent, respectively) compared with clinical evaluation (23.1 percent; P = 0.027).

CONCLUSIONS

Our data suggest that hydrogen peroxide-enhanced ultrasound can be very reliable and useful in the definition of fistula anatomy, its relationship with anal sphincters, and, hence, surgical strategy. It also improves identification of secondary extensions, particularly horseshoe tracks. This method, besides being safe, economic and reputable, both preoperatively and postoperatively, could be helpful in checking operative results and recurrence.

The use of rectal ultrasound for the correct diagnosis and treatment of rectal villous tumors

BACKGROUND

One of the difficulties associated with surgery for rectal villous tumors (RVT) is the finding of invasive adenocarcinoma after transanal excision (TAE) and the possible need for more radical procedures or adjuvant therapy. Improved preoperative evaluation may eliminate this dilemma. The aim of our study was to evaluate the role of transrectal ultrasound (TRUS) in establishing the correct diagnosis of RVT.

METHODS

All patients with biopsy proven RVT, who were referred for TAE, underwent preoperative TRUS in addition to the routine evaluation. If invasion beyond the submucosa was suspected by TRUS, multiple biopsies were taken before any surgical intervention in order to exclude invasive cancer. If no invasion was noted, biopsies were avoided and a TAE was performed. The final pathology results were compared with both the preoperative diagnosis and TRUS results.

RESULTS

Thirty-five patients (19 female, 16 male; mean age 67.5 years, range 36 to 88) were studied. The mean distance of the distal extent of the lesion above the anal verge was 5.8 cm (1.5 to 6). In 27 patients, the tumor was limited to the submucosa (uT0, uT1) on TRUS and, therefore, TAE was performed. In 26 of 27 patients (96%), pathology examination confirmed the presence of RVT without evidence of malignancy. One patient was found to have invasion of the muscularis propria and required postoperative radiation therapy. In 8 patients (23%), TRUS showed extension beyond the submucosa; 3 of these patients had uT2 lesions, 4 had uT3 tumors, and 1 had perirectal nodes. These 8 patients underwent repeated biopsies with the finding of invasive adenocarcinoma in 7. Two patients underwent abdominoperineal resection, 3 had a low anterior resection, and 3 had a TAE. Final pathology confirmed the preoperative diagnosis of invasive adenocarcinoma in 7 patients. In the 1 patient with a uT2 lesion and negative biopsies, the final diagnosis was RVT with no evidence of malignancy.

CONCLUSIONS

Preoperative TRUS provides an accurate diagnosis of RVT. In conjunction with TRUS-directed biopsies, directed management of these tumors could be achieved.

Fistula in ano: evaluation with low-field magnetic resonance imaging (0.1 T)

BACKGROUND

Patients suspected of having perianal suppurative disease often undergo a combination of several potentially painful, invasive procedures to establish or rule out the diagnosis. To evaluate the accuracy of low-field magnetic resonance imaging (MRI) in distinguishing patients with active anal fistulae and patients with no active fistulation we performed a retrospective study.

METHODS

Fifty-six patients suspected of having anal fistulation were evaluated in the surgical outpatient clinic. Patients were examined with low-field MRI (0.1 T; gradient echo technique, TR/TE 1,500/40 and TR/TE 115/25, +/- gadodiamide (0.1 mM/kg intravenously)) in both coronal and axial planes, using a body quadrature coil. Altogether 71 MRIs were performed. In selected patients evaluation included endoanal ultrasonography, fistulography, and/or surgery. On the basis of the combined results of all available follow-up data for 6 months after the MRI, patients were placed in groups either having active fistulation or not.

RESULTS

MRI findings agreed with the combined findings of other examinations in 54 patients. Active or possibly active fistulae were found in 36 cases, whereas 33 patients showed no active fistulae. The kappa value is 0.944 (95% confidence limits, 0.866-1.021). In two patients the MRI findings disagreed with the combined findings of the other modalities.

CONCLUSION

The use of low-field MRI of the pelvic region in the investigation of suspected perianal fistulae is a feasible, reliable, and painless examination. MRI should be considered in patients with suspected complex anal fistulae. Future prospective studies are warranted.

Endosonography in benign anorectal disease: an overview

BACKGROUND

Endosonography may be used for diagnosing various anorectal disorders. This review addresses its technique and clinical use in benign anorectal disease.

METHODS

The English literature available on anal endosonography was reviewed. The different modalities, the endosonography technique itself and its value in benign anorectal disease were described.

RESULTS

Anal endosonography is easy to perform, has a short learning curve and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized and distinction is possible between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. Endosonography is mostly used in the assessment of faecal incontinence; it has brought new insight into the pathophysiological mechanisms of this disorder and can select patients with traumatic incontinence for sphincter repair. It has replaced electromyographical sphincter mapping, which is a painful and time-consuming procedure. In perianal sepsis, endosonography assists in defining fistula tract anatomy. The use of contrast agents has significantly increased the accuracy of endosonography in the assessment of perianal fistulae. In addition, endosonography is an excellent alternative to expensive MRI. Besides its use in incontinence and perianal sepsis, with anal endosonography surgical possibilities can be evaluated in individual patients, for example, to decide whether a sphincter repair or a lateral sphincterectomy is preferable. Finally, endosonography may occasionally identify internal sphincter myopathy in patients with intractable constipation or proctalgia.

CONCLUSION

Anal endosonography images the internal and external sphincters with high accuracy. It is easy to perform and is especially valuable in the diagnosis of anal incontinence and perianal sepsis.

Prospective comparison of endosonography, magnetic resonance imaging and surgical findings in anorectal fistula and abscess complicating Crohn's disease

BACKGROUND

Endosonography and magnetic resonance imaging (MRI) are promising methods for evaluating perineal and anorectal fistulas or abscesses. The aim of this study was to compare the results of anal endosonography (AES), MRI and surgical exploration in the assessment of anorectal fistula or abscess complicating Crohn's disease.

METHODS

Twenty-two patients with Crohn's disease, seven men and 15 women of mean age 38 (range 17-67) years, were included in this prospective study. All patients underwent AES (linear probe 7 MHz), MRI and operative assessment.

RESULTS

AES and MRI demonstrated 14 and nine abscesses respectively, whereas 11 abscesses were confirmed by surgical exploration in ten patients. The sensitivity of AES and MRI as means of evaluating anorectal abscesses was 100 and 55 per cent respectively. The agreement per patient was 86 per cent (19 of 22) for AES and 59 per cent (14 of 22) for MRI. AES and MRI demonstrated 26 and 14 fistulas respectively, whereas 27 fistulas were confirmed during surgical exploration in 16 patients. The sensitivity of AES and MRI was 89 and 48 per cent respectively. The level of agreement per patient was 82 per cent (18 of 22) for AES and 50 per cent (11 of 22) for MRI.

CONCLUSION

AES with a linear probe is more accurate than MRI in detecting anorectal abscesses complicating Crohn's disease, and much more accurate in the evaluation of complex fistulas.

Hydrogen peroxide-enhanced transanal ultrasound in the assessment of fistula-in-ano

Appropriate classification of the fistulous tracts in patients with fistula-in-ano may be of value for the planning of proper surgery. Conventional transanal ultrasound has limited value in the visualization of fistulous tracts and their internal openings. Hydrogen peroxide can be used as a contrast medium for ultrasound to improve visualization of fistulas.

PURPOSE

This prospective study evaluates hydrogen peroxide-enhanced ultrasound in comparison with physical examination, standard ultrasound, and surgery in the assessment of fistula-in-ano.

METHODS

Twenty-one consecutive patients (4 women; mean age, 42 years) with fistula-in-ano were evaluated by local physical examination (inspection, probing, and digital examination), conventional ultrasound, and hydrogen peroxide-enhanced ultrasound before surgery. Ultrasound was performed using a B&K Diagnostic Ultrasound System with a 7-MHz rotating endoprobe. Hydrogen peroxide (3%) was infused via a small catheter into the fistula. The results of physical examination, ultrasound, and hydrogen peroxide-enhanced ultrasound were compared with surgical data as the criterion standard. The additive value of standard ultrasound and hydrogen peroxide-enhanced ultrasound compared with physical examination was also determined.

RESULTS

At surgery, 8 intersphincteric and 11 transsphincteric fistulas and 2 sinus tracts (without an internal opening) were found. During physical examination, probing was incomplete in 13 patients, the diagnosis being correct in the other 8 patients (38%) as a low (intersphincteric or transsphincteric) fistula. With conventional ultrasound, the assessment of fistula-in-ano was correct in 13 patients (62%); defects in one or both sphincters could also be found (n = 8). With hydrogen peroxide-enhanced ultrasound, the fistulous tract was classified correctly in 20 patients, the overall concordance with surgery being 95%. The internal opening was found at physical examination in 15 patients (71%), with hydrogen peroxide-enhanced ultrasound in 10 patients (48%), and during surgery in 19 patients (90%). Secondary extensions, confirmed during surgery, were found in five cases. In two patients, a secondary extension with hydrogen peroxide-enhanced ultrasound was not confirmed during surgery. Both patients developed a recurrent fistula.

CONCLUSION

Hydrogen peroxide-enhanced ultrasound is superior to physical examination and standard ultrasound in delineating the anatomic course of perianal fistulas. It makes accurate preoperative assessment of the fistula possible and may be of value for the surgeon in planning therapeutic strategy.

Endorectal ultrasound

Endorectal ultrasound is a very useful diagnostic adjunct for benign and malignant anorectal diseases. The only prerequisite in performing this test is that the examiner appreciate the impact that EUS has on the clinical management of patients. For example, the information obtained when scanning rectal cancer dictates whether local excision (i.e., sphincter preservation) or preoperative adjuvant therapy followed by radical resection is chosen. For benign disease, EUS helps direct therapy for patients with fecal incontinence and selects those patients most likely to benefit from reconstructive surgery.

Vaginal endosonography of the anal sphincter complex is important in the assessment of faecal incontinence and perianal sepsis

BACKGROUND

Anal endosonography is an established technique in the evaluation of anorectal disease. However, it is sometimes difficult to visualize the anterior part of the sphincter complex and anal endosonography may be impossible when anal pain or stenosis is present. The aim of this study was to evaluate vaginal endosonography in the diagnosis of faecal incontinence and perianal sepsis.

METHODS

Anal and vaginal endosonography were performed in 56 women with faecal incontinence (n = 36) or perianal sepsis (n = 20). The technique and pelvic floor anatomy were described, anal sphincter measurements with anal and vaginal endosonography were compared, and the additive value of vaginal over anal endosonography in the diagnosis of faecal incontinence and perianal sepsis was assessed.

RESULTS

The pelvic floor was clearly imaged with vaginal endosonography. However, after a relatively short learning curve it was still not possible to image the anal sphincters in three of 28 patients. Except for external anal sphincter thickness, which was significantly lower, all anal canal structure measurements were greater with vaginal than with anal endosonography. Concerning the diagnosis of either faecal incontinence or perianal sepsis, vaginal endosonography added important information in comparison with anal endosonography in 14 (25 per cent) of 56 patients.

CONCLUSION

Vaginal endosonography provides reliable images of the anal sphincters in an undistorted fashion, thereby increasing the diagnostic yield of faecal incontinence and perianal sepsis in 25 per cent of patients. Therefore, endosonographists should become acquainted with this technique.