Transperineal versus hydrogen peroxide-enhanced endoanal ultrasonography in never operated and recurrent cryptogenic fistula-in-ano: a pilot study

Background Accurate delineation of anal fistula anatomy in recurrent cases will assist in surgical fistula eradication whilst preserving continence. Recently, transperineal ultrasonography (TPUS) has been used in perirectal inflammation where there may be advantage over endoanal ultrasonography (EAUS) in complex fistulae- in-ano which lie outside the focal range of the endoanal probe. We assessed the sensitivity of these two imaging modalities to characterize fistula-in-ano, compared to surgical findings. Methods Hand-held 7.5 MHz TPUS was performed in the axial and sagittal planes in never-operated (Group 1, n=10) and recurrent (Group 2, n=10) cryptogenic fistulae where the ultrasonographer was blinded to the initial operative findings. This was compared with hydrogen peroxide-enhanced EAUS using a 7.5 MHz rotating probe, assessing the fistula anatomy, site of the internal opening, confirmation of Goodsall’s rule and the presence of secondary tracks, abscess collections and significant horsehoeing of the track. Results Overall sensitivity for the detection of trans-sphincteric and extrasphincteric fistulae was 100% using both techniques with a 90% sensitivity for TPUS and an 85% sensitivity for EAUS in the prediction of the internal fistula opening site. The TPUS sensitivity for horseshoeing was poor (28.6%) as was the detection of ancillary abscesses confirmed at surgery (63.6%) but TPUS demonstrated rectovaginal fistulae. Conclusion TPUS is a novel technique for use in perirectal infection which has a significant learning curve but which is highly accurate for prediction of the anatomy of complex recurrent as well as simple anal fistulae. An erratum to this article is available at .     

Ultrasound Study of Anal Fistulas With Hydrogen Peroxide Enhancement

PURPOSE: This study was designed to evaluate the effectiveness of hydrogen peroxide-enhanced, endoanal ultrasound in the assessment of fistula-in-ano and compare ultrasonographic results with the surgical outcome. METHODS: A total of 80 patients with anal fistula were studied prospectively by physical examination and endoanal ultrasound enhanced with hydrogen peroxide. We used standarized ultrasonography and operation notes. The results of these studies were compared with the surgical findings. The ultrasonographic study of the anal canal describes the fistulas characteristics, which provides an ultrasonographic classification of the fistula. All endoanal ultrasounds were performed by colorectal surgeons. RESULTS: In 94 percent of the cases, the internal opening was identified. In only one case were we unable to obtain sufficient information about the tract and the fistulas level. The endoanal ultrasound was able to correctly identify whether the tract was linear or curvilinear in 95 percent of the cases. The ultrasound level coincided with surgical findings in 85 percent of patients, and chronic fistula cavities were confirmed by surgery in 75 percent of patients. CONCLUSIONS: The use of endoanal ultrasound, with hydrogen peroxide enhancement, by a colorectal surgeon with adequate experience in endoanal ultrasound provides excellent results in the presurgical examination of fistula-in-ano.     

Value of Hydrogen Peroxide Enhancement of Three-Dimensional Endoanal Ultrasound in Fistula-in-Ano

PURPOSE The aim of this prospective study was to compare the accuracy of three-dimensional endoanal ultrasound with that of hydrogen peroxide enhanced three-dimensional endoanal ultrasound in diagnosing recurrent or complex fistula-in-ano.METHODS Three-dimensional endoanal ultrasound reconstructions were performed before and after hydrogen peroxide enhancement in 19 patients with suspected recurrent or complex fistula-in-ano. Two experienced observers derived a consensus fistula classification after a blinded random review of the data sets. The accuracy of three-dimensional endoanal ultrasound and that of hydrogen peroxide–enhanced three-dimensional endoanal ultrasound were compared with a reference standard derived from surgical findings and magnetic resonance imaging and modified by outcome over a median follow-up of 13 months.RESULTS Patients had previously undergone a median of three fistula operations. Four had Crohns disease. There were 21 internal openings and primary tracks in 19 patients: 1 superficial, 1 intersphincteric, 18 transsphincteric, and 1 extrasphincteric. Fourteen patients had 19 secondary tracks. Both techniques detected fistula tracks in 19 of 21 (90 percent) patients. There was no significant difference between three-dimensional endoanal ultrasound and hydrogen peroxide–enhanced three-dimensional endoanal ultrasound in classifying internal openings (19/21 (90 percent) vs. 18/21 (86 percent)), primary tracks (17/21 (81 percent) vs. 15/21 (71 percent)), or secondary tracks (13/19 (68 percent) vs. 12/19 (63 percent)). Where three-dimensional endoanal ultrasound correctly detected an internal opening, gas from hydrogen peroxide enhancement was present in 8 of 18 (44 percent) studies. Similarly, gas made primary tracks more conspicuous in 6 of 19 (32 percent) and secondary tracks in 6 of 13 (46 percent) of those detected.CONCLUSIONS In recurrent or complex fistula-in-ano, endoanal ultrasound proved more accurate for detecting primary tracks and internal openings than for detecting extensions. Hydrogen peroxide improved conspicuity of some tracks and internal openings and so may be helpful in difficult cases, although no overall diagnostic benefit was demonstrated.Gordon Buchanan was funded by the St. Marks Hospital Foundation.     

How can the assessment of fistula-in-ano 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.Presented at The American Society of Colon and Rectal Surgeons' 100^th Anniversary and Tripartite Meeting, Washington, D.C., May 1 to 6, 1999.     

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.     

Prospective Comparison of Hydrogen Peroxide–Enhanced Three-Dimensional Endoanal Ultrasonography and Endoanal Magnetic Resonance Imaging of Perianal Fistulas

PURPOSE: This study was conducted to determine agreement between hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging in the preoperative assessment of perianal fistulas and to compare these results with the surgical findings. METHODS: Twenty-one patients (aged 26–71 years) with clinical symptoms of a cryptoglandular perianal fistula and a visible external opening underwent preoperative hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography, endoanal magnetic resonance imaging, and surgical exploration. The results were assessed separately by experienced observers blinded as to each others findings. Each fistula was described with notice of the following characteristics: classification of the primary fistula tract according to Parks (intersphincteric, transsphincteric, extrasphincteric, or suprasphincteric), horseshoe, or not classified; presence of secondary tracts (circular or linear); and location of an internal opening. RESULTS: The median time between hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging was 66 (interquartile range, 21–160) days; the median time between the last study (hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography or endoanal magnetic resonance imaging) and surgery was 154 (interquartile range, 95–189) days. Agreement for the classification of the primary fistula tract was 81 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and surgery, 90 percent for endoanal magnetic resonance imaging and surgery, and 90 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging. For secondary tracts, agreement was 67 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and surgery, 57 percent for endoanal magnetic resonance imaging and surgery, and 71 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging in case of circular tracts and 76 percent, 81 percent, and 71 percent, respectively, in case of linear tracts. Agreement for the location of an internal opening was 86 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and surgery, 86 percent for endoanal magnetic resonance imaging and surgery, and 90 percent for hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging. CONCLUSIONS: For evaluation of perianal fistulas, hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging have good agreement, especially for classification of the primary fistula tract and the location of an internal opening. These results also show good agreement compared with surgical findings. Therefore, hydrogen peroxide–enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging can both be used as reliable methods for preoperative evaluation of perianal fistulas.     

Diagnostic Accuracy of Three-Dimensional Endoanal Ultrasound for Anal Fistula: A Systematic Review and Meta-analysis

Background: Anal fistula is a relatively common anorectal disease. An accurate assessment of the main anal fistula type and the ­anatomy of the internal opening before surgery is necessary to obtain the best surgical results. Whether three-dimensional endoanal ultrasound (3D-EAUS) should be used as the first-line diagnostic tool for anal fistula is still controversial. The purpose of this study is to conduct a meta-analysis of the published literature on 3D-EAUS and anal fistula, and compare the results of 3D-EAUS and surgery to evaluate the diagnostic value of 3D-EAUS for anal fistula.Methods: An online search of databases in English included PubMed, Embase, and Cochrane Library. After the diagnostic accuracy of 3D-EAUS of all anal fistula types was integrated, a single-group rate meta-analysis was performed; we analyzed 3D-EAUS separately for the diagnosis of different anal fistula types, and conducted a meta-analysis of test accuracy. The analysis combined sensitivity, specificity, and the respective 95% CI, to draw a summary receiver operating characteristic curve (SROC), and estimate the area under curve (AUC).Results: Based on the inclusion criteria, we selected 8 studies covering 1057 cases of anal fistula and 548 cases of internal opening. The meta-analysis data show that 3D-EAUS has a total accuracy rate of 91% (95% CI, 88-94%). It has high sensitivity and specificity for different anal fistula classifications. The SROC curves for anal fistula internal openings were plotted, and the AUC was calculated to be 0.86 (95% CI, 0.83-0.89).Conclusions: 3D-EAUS can be used as the first-line diagnostic tool for anal fistula, because it has a high diagnostic accuracy for most anal fistulas. However, due to the insufficient diagnostic accuracy of 3D-EAUS for complex fistulas, 3D-EAUS combined with MRI examination can be used to more accurately detect the secondary extension of complex fistulas, so as to describe the complete anatomy of the fistula in more detail.     

Use of endoanal ultrasound in patients with rectovaginal fistulas

PURPOSE: The purpose of our study was to define the role of endoanal ultrasound in the evaluation and management of patients with rectovaginal fistula. METHODS: A retrospective review was performed of all patients with rectovaginal fistula who were evaluated by endoanal ultrasound at Barnes-Jewish Hospital at Washington University from 1992 to 1997. RESULTS: Twenty-five females underwent endoanal ultrasound before rectovaginal fistula repair. Mean age was 34 years. Rectovaginal fistulas were caused by obstetric trauma (19 patients; 76 percent), cryptoglandular disease (5 patients; 20 percent), and Crohn's disease (1 patient; 4 percent). Previous rectovaginal fistula repair had been performed in ten patients (40 percent). A history of anal incontinence was present in ten patients (40 percent). Rectovaginal fistula location was above (15 patients), at (7 patients), or below (3 patients) the dentate line. Rectovaginal fistula size was <5 mm (19 patients; 76 percent) or >5 mm (6 patients; 24 percent). Anal manometry revealed decreased sphincter pressures (resting or squeeze) in 12 patients (48 percent). Pudendal nerve latency was abnormal in three patients (9 percent). Endoanal ultrasound identified the rectovaginal fistula in 7 patients (28 percent) and an anterior sphincter defect in 23 patients (92 percent). At surgery sphincter injuries were identified in 23 patients (92 percent). Treatment was either sliding flap repair with anal sphincter reconstruction (22 patients; 88 percent) or sliding flap repair alone (3 patients; 12 percent). Repair of the rectovaginal fistula was successful in 23 patients (92 percent). Complications occurred in 11 patients (44 percent): two recurrent rectovaginal fistulas, five infections, two skin separations, one ectropion, and one hematoma. The two patients with recurrent rectovaginal fistula had prior repairs, and both were subsequently repaired successfully. Of the 11 patients with preoperative anal incontinence, 6 patients (54 percent) were continent and 2 (18 percent) improved after surgery. Cause, size, location, and previous repair of fistula had no effect on final outcome. CONCLUSIONS: Noncontrast endoanal ultrasound was not useful in imaging rectovaginal fistulas and cannot be recommended as a diagnostic or screening tool for the identification of a rectovaginal fistula. However, we recommend that endoanal ultrasound be performed preoperatively in all patients with known rectovaginal fistulas to identify and map occult sphincter defects. Concomitant anal sphincter reconstruction should be considered strongly in patients with rectovaginal fistula and an endoanal ultrasound-documented sphincter defect.Read at the meeting of The American Society of Colon and Rectal Surgeons, San Antonio, Texas, May 2 to 7, 1998.     

Endoanal ultrasound in perianal fistulas and abscesses

Anal ultrasound has demonstrated 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 becomes then visible as a hyperechoic lesion ('white'). It has been shown that this corresponds excellent with surgical findings. It is equally sensitive as endoanal MRI. Because recurrent cryptoglandular fistulae are complex in about 50% and Crohn's fistula in 75%, it is mandatory to perform anal ultrasound preoperative in these patients to avoid missed tracks during surgery and subsequent recurrences. Anal ultrasound can also be used to monitor (medical) therapy in patients with Crohn's disease. Especially considering the easiness of performing and lesser costs then MRI, endoanal ultrasound merits more attention.     

Peroxide-enhanced endoanal ultrasound in preoperative assessment of complex fistula-in-ano

Background

In complex fistula-in-ano, preoperative imaging can help identify secondary tracts and abscesses that can be missed, leading to recurrence. We evaluated hydrogen peroxide-enhanced endoanal ultrasound (PEEUS) in the characterization of fistula compared with standard clinical and operative assessment.

Methods

Patients with complex fistula-in-ano treated between February 2008 and May 2009 at our institution were prospectively evaluated by PEEUS with recording of the preoperative clinical examination and intraoperative details of the fistula. Of the 135 patients with fistula-in-ano, 68 met the inclusion criteria for complex fistula-in-ano. Correlation of clinical findings and PEEUS to the gold standard intraoperative findings was assessed in characterizing the fistula. The percent agreement between the clinical and PEEUS findings against the gold standard was derived, and the kappa statistic for agreement was determined.

Results

The mean age of the cohort was 42.54 ± 10.86 years. The fistula tracts were curvilinear, high, and transsphincteric in 16 (23.53 %), 8 (11.76 %), and 42 (61.76 %) patients, respectively. Secondary tracts and associated abscess cavities were seen in 28 (33.82 %) and 35 (51.47 %) patients, respectively. PEEUS correlated better than clinical examination with regard to site (92.65 vs 79.41 %; p < 0.001) and course (91.18 vs 77.94 %; p < 0.001) of secondary tract and associated abscesses (89.71 vs 80.88 %; p = 0.02). There was a trend of better correlation of PEEUS compared to clinical examination in classifying the primary tract as per Park’s system (88.24 vs 79.41 %; p = 0.06), but it did not reach statistical significance. PEEUS and clinical examination were comparable in correlation of the level of the primary tract (kappa: 0.86 vs 0.78; p = 0.22) and the site of internal opening (kappa: 0.97 vs 0.89; p = 0.22). The operative decision was changed in 13 (19.12 %) subjects based on PEEUS findings.

Conclusions

PEEUS is a feasible and efficient tool in the routine preoperative assessment of complex fistula-in-ano.     

Three-dimensional endoanal ultrasonographic assessment of an anal fistula with and without H2O2 enhancement

AIM： To evaluate the effectiveness of three-dimensional endoanal ultrasound （3D-EAUS） in the assessment of anal fistulae with and without H202 enhancement. METHODS： Sixty-one patients （37 males, aged 17-74 years） with anal fistulae, which were not simple low types, were evaluated by physical examination and 3D-EAUS with and without enhancement. Fistula classification was determined with each modality and compared to operative findings as the reference standard. RESULTS： The accuracy of 3D-EAUS was significantly higher than that of physical examination in detecting the primary tract （84.4% vs 68.7%, P = 0.037） and secondary extension （81.8% vs 62.1%, P = 0.01） and localizing the internal opening （84.2% vs 59.7%, P = 0.004）. A contrast study with H202 detected several more fistula components including two primary suprasphincteric fistula tracks and one supralevator secondary extension, which were not detected on non-contrast study. However, there was no significant difference in accuracy between 3D-EAUS and H202- enhanced 3D-EAUS with respect to classification of the primary tract （84.4% vs 89.1%, P = 0.435） or secondary extension （81.8% vs 86.4%, P = 0.435） or localization of the internal opening （84.2% vs 89.5%, P = 0.406）. CONCLUSION： 3D-EAUS was highly reliable in the diagnosis of an anal fistula. H2O2 enhancement was helpful at times and selective use in difficult cases may be economical and reliable.     

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 infusedvia 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.Dr. Poen was supported by a grant from Janssen-Cilag B.V., The Netherlands.Presented in part at the United European Gastroenterology Week, Birmingham, United Kingdom, October 18 to 21, 1997.     

Accuracy of hydrogen peroxide enhanced endoanal ultrasonography in assessment of the internal opening of an anal fistula complex

Abstract. Background: The aim of this study was to evaluate the accuracy of hydrogen peroxide-enhanced ultrasound in localizing the internal opening of the anal fistula. Methods: A retrospective review of all patients with anal fistula who underwent hydrogen peroxide-enhanced ultrasound was performed. The results of hydrogen peroxideenhanced ultrasound and intraoperative findings on the basis of operative reports were correlated. Results: A total of 57 patients (47 men) of mean age of 45.7 (range, 21–77) years underwent hydrogen peroxide-enhanced ultrasound with a diagnosis of anal fistula; 36 patients underwent surgery. The intraoperative internal opening correlated with the hydrogen peroxide-enhanced ultrasound report in 22 of 36 patients (61.1%). In 5 patients, the hydrogen peroxide-enhanced ultrasound yielded false-positive information with a positive predictive value of 84%. Four of the 7 patients with falsenegative hydrogen peroxide-enhanced ultrasound findings had supra- and extrasphincteric fistulas. Conclusions: There is a 61.1% correlation between hydrogen peroxide-enhanced ultrasound and surgical findings of the internal opening with a positive predictive value of 84%. If no internal opening was seen on hydrogen peroxide-enhanced ultrasound, it strongly suggests the possibility of a supralevator or extrasphincteric fistula.Presented at the Annual Meeting of the American Society of Colon and Rectal Surgeons, 1–7 May 1999, Washington D. C., USA.     

A pilot assessment of whether external coil MRI is useful to assess evacuatory disorders

This study assessed the value of common surface coil mag-netic resonance imaging (MRI) in patients with evacuatory disorders including fecal incontinence and constipation. These findings were then compared with those from other standard physiological examinations and/or surgical findings. From July 1996 to June 1997, 14 consecutive patients underwent surface coil MRI for evaluation of either fecal incontinence (n=5) or constipation (n=9). In patients with incontinence we compared the findings from endoanal ultrasound (EAUS), anal MRI, and surgery regarding morphopathological findings of the internal and external anal sphincter components. In constipated patients the findings of videoprography and dynamic pelvic MRI were compared regarding the presence of rectocele, rectoanal intussusception, and sigmoidocele as well as the measurements of anorectal angle and perineal descent. The five incontinent patients were all women, with a median age of 67 years (range 43–77). EAUS revealed an anterior sphincter defect in two patients, a posterior defect in one, and normal anal sphincter images in two. Surgical findings confirmed an anterior external anal sphincter scar in two patients, an internal anal sphincter defect in one, and an anatomically normal anal sphincter in two. In one patient, although anal MRI showed posterior external anal sphincter defect, EAUS and surgery revealed normal external anal sphincter appearance. The accuracy rate between EAUS and anal MRI was only 20%, that between surgery and anal MRI 40%, and that between surgery and EAUS 80%. Thus EAUS was more accurate than anal MRI in incontinent patients. The nine constipated patients were all women, with a mean age of 59 years (range 40–78). Videoproctography revealed an anterior rectocele in six patients, rectoanal intussusception in three, and sigmoidocele in five; no abnormalities were identified in two patients. On dynamic pelvic MRI anterior rectocele was seen in three patients and sigmoidocele in two, and five studies were interpreted as normal. One of the patients underwent sigmoidectomy for sigmoidocele, and five patients were treated by biofeedback. Thus the accuracy rate of dynamic pelvic MRI against videoproctography was 60% for anterior rectocele, 40% for sigmoidocele, and zero for rectoanal intussusception. In conclusion, neither MRI for the evaluation of patients with fecal incontinence nor for the evaluation of patients with constipation added any significant information that would warrant its continued use in these patient groups. Perhaps the more widespread availability of an endoanal coil will alter this conclusion; however, at the present time we cannot routinely endorse the expense, time, or inconvenience of these MRI investigations in patients with these diagnoses. Larger prospective comparative studies are required prior to endorsing the technique. Accepted: 21 February 2000     

Conventional cutting vs. internal anal sphincter-preserving seton for high trans-sphincteric fistula: a prospective randomized manometric and clinical trial

Abstract. Background: Cutting setons have been used in complicated perirectal sepsis with good effect, although there is a moderately high incidence of fecal leakage after their use. The aim of this study was to compare a modified cutting seton, which repaired the internal anal sphincter muscle and re-routed the seton through the intersphincteric space, with a conventional cutting seton. Methods: A total of 34 patients were randomized between 1998 and 2002. They were prospectively assessed by continence score and anorectal manometry, and for anal function, clinical sepsis and fistula recurrence. Results: There was no difference in postoperative continence score, incidence of recurrent fistula or healing time between groups after a mean follow-up of 12 months. Resting anal manometric pressures and vector volumes were consistently higher with the modified seton (although not statistically significant), as was the area under the inhibitory curve during elicitation of the rectoanal inhibitory reflex across the full sphincter length. (p<0.05). Conclusion: A larger prospective study of internal anal sphincter-preserving seton use in cryptogenic high transshincteric fistula-in-ano appears justified.     

Anal endosonography for recurrent anal fistulas: Image enhancement with hydrogen peroxide

Anal endosonography is a new technique that is useful in the preoperative assessment of patients with anal fistulas. Endosonographic images are created by the reflection of sound waves from the interfaces between tissues of varying densities. In order to accentuate tissue interface layers at the level of the fistula tract, we introduced hydrogen peroxide into the fistula tract through the external opening during anal ultrasonography in two patients with recurrent anal fistula. Hydrogen peroxide injection resulted in hyperechoic imaging of the preinjection hypoechoic horseshoe fistula tract. Endosonographic findings were confirmed at the time of surgery in both patients. We conclude that hydrogen peroxide enhancement of the fistula tract is a simple, effective, and safe method of improving the accuracy of endoanal ultrasound assessment of recurrent anal fistula.Dr. Cheong is a visiting clinician from the Department of Surgery, Tan Tock Seng Hospital, Moulmein Road, Singapore 1130.     

Comparison of accuracy of physical examination and endoanal ultrasonography for preoperative assessment in patients with acute and chronic anal fistula

Background

This study was undertaken to evaluate the accuracy of endoanal ultrasonography for preoperative assessment of anal fistula, with special reference to the difference between acute and chronic fistula.

Methods

The subjects comprised 401 patients treated for acute or chronic anorectal sepsis of cryptoglandular origin during the period January through December 2005. All patients underwent physical examination and endoanal ultrasonography. Agreement between the physical and endosonographic findings and the definitive surgical findings were evaluated with special reference to classification of the primary tract and horseshoe extension and localization of the internal opening. The difference in accuracy of endosonographic assessment between acute and chronic fistula was also evaluated.

Results

The accuracy of endoanal ultrasonography was significantly higher than that of physical examination in detecting the primary tract (88.8% vs. 85.0%, p=0.0287) and horseshoe extension (85.7% vs. 58.7%, p<0.0001) and in localizing the internal opening (85.5% vs. 69.1%, p<0.0001). Furthermore, localization of the internal opening by endosonography was significantly more accurate in chronic fistula than in acute fistula (89.5 % vs. 76.8%, p<0.0001), although the accuracy in detecting the primary tract and horseshoe extension was not significantly different.

Conclusions

Endoanal ultrasonography is reliable and useful for preoperative assessment of anal fistula, particularly for detecting horseshoe extension and localizing the internal opening. Endosonographic assessment provides clearer depiction of the internal opening during periods of quiescence than during the period of abscess formation. For patients with acute anorectal sepsis, initial surgical drainage and subsequent fistula surgery, rather than one-stage fistula surgery, may be advisable to avoid misidentification of the internal opening.     

New horizons in the imaging of perianal Crohn’s disease: transperineal ultrasonography

Introduction: perianal disease, most commonly manifest as fistula or abscess formation, affects up to 40% of patients with crohn’s disease. perianal crohn’s disease is disabling, associated with poor outcomes, and represents a therapeutic challenge for physicians. correct diagnosis and classification of perianal disease is the first crucial step for appropriate multidisciplinary management.

Areas covered: A literature search was performed of the PubMed database using the terms ‘transperineal ultrasonography’, ‘transperineal ultrasound’, ‘perianal disease’, ‘perianal fistula’, ‘perianal abscess’, ‘magnetic resonance’, ‘endoanal ultrasonography’, ‘endoscopic ultrasound’ in combination with ‘Crohn’s disease’. A comprehensive review of the relative advantages and disadvantages of the various methods of evaluation of perianal Crohn’s disease is provided. A particular focus is placed on transperineal ultrasonography, including historical and technical factors, advantages and limitations, and its current role in practice. An algorithm for integration of transperineal ultrasound into the management of perianal Crohn’s disease into clinical practice is proposed, along with future areas research.

Expert commentary: Transperineal ultrasound is a simple, safe, cheap and reliable imaging technique for evaluation of perianal Crohn’s disease, which should be used more frequently in clinical practice.     

Anal Fistula: Levovist®-Enhanced Endoanal Ultrasound

PURPOSE: The aim of the study was to investigate the usefulness of the contrast agent Levovist® in ultrasound assessment of anal fistula. METHODS: Fifteen patients (11 females, mean age 46) with a diagnosis of anal fistula were assessed by physical examination, conventional ultrasound, Levovist®-enhanced ultrasound, and surgery. Levovist® was injected via a cannula into the fistula. The results of physical examination, conventional ultrasound and Levovist®-enhanced ultrasound were compared with surgical findings as criterion standard. RESULTS: At physical examination, three intersphincteric fistulas and two sinuses were diagnosed. Using conventional ultrasound, five intersphincteric and five transsphincteric fistulas were found; four fistulas and one sinus were not detected. Levovist®-enhanced ultrasound revealed one sinus, five intersphincteric, seven transsphincteric, and one extrasphincteric fistulas; only one fistula was not detected. At surgery, three intersphincteric, seven transsphincteric, and two sinuses were found; however, the extrasphincteric fistula detected by Levovist® was missed. Compared with physical examination, Levovist®-enhanced ultrasound and surgery were significantly favorable in the diagnosis of anal fistula (P < 0.05 in chi-squared test and Fishers exact probability test). The concordance rate of surgery with conventional ultrasound was 69 percent (9/13) and with Levovist®-enhanced ultrasound was 77 percent (10/13). However, because the extrasphincteric fistula was missed at surgery, the accuracy of Levovist®-enhanced ultrasound was in fact 85 percent (11/13) if surgical finding was not used as the standard. The internal opening was detected at physical examination in 2 patients (13 percent), with conventional ultrasound in 4 patients (27 percent), with Levovist®-enhanced ultrasound in 9 patients (60 percent) and during surgery in 11 patients (85 percent). Consistently, Levovist®-enhanced ultrasound and surgery were significantly better than physical examination in the diagnosis of internal opening (P < 0.05). One secondary extension and two sphincter defects were detected by both types of ultrasound. The extension was not confirmed during surgery. No patients developed recurrence or nonhealing of wound. One patient developed incontinence to flatus and one developed a perianal hematoma. CONCLUSION: Levovist®-enhanced ultrasound is better at assessing anal fistula than physical examination and conventional ultrasound. However, a future trial comparing Levovist®, hydrogen peroxide, and magnetic resonance imaging is needed to establish which is the most cost-effective preoperative imaging technique to use.     

Radiologic evaluation of anorectal disorders

Defecation is a dynamic event, and although evacuation proctography does not simulate physiologic defecation exactly, it does provide maximal stress to the pelvic floor and image rectal emptying, both of which are required for the diagnosis of certain conditions: MR imaging studies are attractive in that no ionizing radiation is involved, but unless an evacuation study is performed, the features of anismus, trapping in a rectocele, and intussusception cannot be diagnosed. Because these are the main reasons for investigating difficult defecation, the fluoroscopic examination is the simplest and most reliable method. Endoanal ultrasound is an ideal screening examination for incontinence to show internal sphincter degeneration and tears of the internal or external sphincters. The diagnosis of external sphincter atrophy on ultrasound is not yet resolved, and this remains an important indication for endoanal MR imaging.