***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES : The complexity of anal fistulas is different in patients with and without Crohn 's disease and in men and women . This may affect the localization of the internal orifice . We compared the characteristics of anal fistulas and the accuracy of Goodsall 's rule in predicting the position of the internal orifice in male and female Crohn 's and non-Crohn 's patients . METHODS : A total of 191 fistula tracks in 182 consecutive patients ( 110 men and 72 women ) were analyzed prospect ively . Of the patients , 63 were diagnosed with Crohn 's disease . The positions of the orifices were recorded and the accuracy of Goodsall 's rule determined . RESULTS : The distribution of fistula subtypes among Crohn 's and non-Crohn 's patients differed signficantly ( p = 0.0471 ) . Fistulas with an anterior external opening occurred more frequently in Crohn 's patients ( p = 0.0350 ) and in women ( p = 0.0030 ) . Fistulas with a posterior external orifice were observed more frequently in non-Crohn 's patients ( p = 0.0350 ) and in men ( p = 0.0028 ) . Overall , Goodsall 's rule performed less well in women compared with men ( p = 0.0633 ) . The accuracy of Goodsall 's rule overall was not affected by Crohn 's disease . In female non-Crohn 's patients , the positive predictive value of a posterior external orifice was lower than in men ( p = 0.0406 ) . CONCLUSIONS : The distribution of fistula subtypes and the ratio of anterior and posterior external openings among Crohn 's and non-Crohn 's patients differ significantly . Many fistulas defy Goodsall 's rule , particularly in women and when applied to fistulas with anterior external orifices . The popular rule , however , falls equally short in Crohn 's and non-Crohn 's fistulas OBJECTIVE It has been suggested that fistula in ano is most accurately assessed using endoanal receiver coils because they provide superior spatial resolution . We aim ed to determine their advantage by prospect i ve comparison with conventional body coil imaging . SUBJECTS AND METHODS Thirty consecutive unselected patients with a diagnosis of anorectal sepsis were examined by MR imaging with an endoanal coil . Imaging with a body coil followed . Imaging was independently evaluated by two radiologists who classified fistulas according to the coil used and then compared their findings , which were vali date d surgically . RESULTS Five patients could not tolerate coil insertion . In the remaining 25 patients , endoanal imaging revealed no abnormalities in three patients in whom the body coil image correctly showed Crohn 's disease , a sinus , and a transsphincteric fistula . Imaging with both coils revealed sepsis in 16 patients , allowing radiologists to make correct primary track classification in 13 patients on endoanal imaging compared with 15 patients on body coil imaging . Endoanal imaging revealed 10 secondary extensions in eight patients , but further extensions in two of these patients and in a third patient were undetected . All these extensions were seen on body coil imaging . Overall , surgical concordance was 68 % for endoanal imaging compared with 96 % for conventional body coil imaging . CONCLUSION Due to field-of-view limitations , endoanal imaging is less accurate than conventional body coil imaging for preoperative assessment of complex anal fistulas PURPOSE To prospect ively evaluate the relative accuracy of digital examination , anal endosonography , and magnetic resonance ( MR ) imaging for preoperative assessment of fistula in ano by comparison to an outcome -derived reference st and ard . MATERIAL S AND METHODS Ethical committee approval and informed consent were obtained . A total of 104 patients who were suspected of having fistula in ano underwent preoperative digital examination , 10-MHz anal endosonography , and body-coil MR imaging .  Fistula classification was determined with each modality , with review ers blinded to findings of other assessment s. For fistula classification , an outcome -derived reference st and ard was based on a combination of subsequent surgical and MR imaging findings and clinical outcome after surgery . The proportion of patients correctly classified and agreement between the preoperative assessment and reference st and ard were determined with trend tests and kappa statistics , respectively . RESULTS There was a significant linear trend ( P < .001 ) in the proportion of fistula tracks ( n = 108 ) correctly classified with each modality , as follows : clinical examination , 66 ( 61 % ) patients ; endosonography , 87 ( 81 % ) patients ; MR imaging , 97 ( 90 % ) patients . Similar trends were found for the correct anatomic classification of abscesses ( P < .001 ) , horseshoe extensions ( P = .003 ) , and internal openings ( n = 99 , P < .001 ) ; endosonography was used to correctly identify the internal opening in 90 ( 91 % ) patients versus 96 ( 97 % ) patients with MR imaging . Agreement between the outcome -derived reference st and ard and digital examination , endosonography , and MR imaging for classification of the primary track was fair ( kappa = 0.38 ) , good ( kappa = 0.68 ) , and very good ( kappa = 0.84 ) , respectively , and fair ( kappa = 0.29 ) , good ( kappa = 0.64 ) , and very good ( kappa = 0.88 ) , respectively , for classification of abscesses and horseshoe extensions combined . CONCLUSION Endosonography with a high-frequency transducer is superior to digital examination for the preoperative classification of fistula in ano . While MR imaging remains superior in all respects , endosonography is a viable alternative for identification of the internal opening Objectives The assessment of complicated anal fistulae is based on digital examination . Our objective was to study the potential role of MRI in this setting by comparing preoperative digital examination with MRI . Material s and Methods Digital examination and MRI were prospect ively and blindly interpreted in 13 patients with complicated anal fistulae . Surgical findings were used as st and ard . Results Complete agreement between the results of digital examination and the surgical findings was observed in 8 patients and between the results of MRI and the surgical findings in 12 patients . Digital examination misclassified two low transsphincteric fistulae as high transsphincteric and missed high secondary extensions or abscesses in three other patients . Magnetic resonance misclassified only one suprasphincteric fistula as low transsphincteric and did not overlook high secondary extensions or abscesses . Conclusion These findings suggest that MRI may show abnormalities not detected by preoperative digital examination A prospect i ve trial was performed comparing the accuracy of digital examination and anal endosonography in defining the anatomy of  anal fistulae .  Before operation 38 consecutive patients were assessed by the consultant in charge of the case , by a research fellow and by anal endosonography involving two radiologists . These findings were compared with the operative findings . Consultants correctly identified 26 of 33 internal openings , 29 of 34 primary tracks and 15 of 21 secondary tracks . The research fellow correctly identified 26 internal openings , 24 primary tracks and 10 secondary tracks . There was no significant difference between the accuracy of consultants and the research fellow . Anal endosonography identified 10 internal openings based on initial criteria . This rose to 24 when revised ultrasonographic criteria were applied . There was no statistical difference between consultant assessment and anal ultrasonography in correctly identifying intersphincteric and transphincteric tracks . Ultrasonography is unable to assess primary superficial , suprasphincteric and extrasphincteric tracks or secondary supralevator and infralevator tracks . Consultant assessment of secondary supralevator and infralevator tracks was correct in 78 per cent of cases AIMS : To prospect ively determine if rectal endoscopic ultrasound ( EUS ) can guide combination medical and surgical therapy and improve outcomes for patients with perianal fistulizing Crohn 's disease . METHODS : Ten patients with perianal Crohn 's disease were prospect ively enrolled in a r and omized prospect i ve pilot study . The patients were r and omized to either the EUS cohort or the control group . All patients underwent a rectal EUS to delineate fistula anatomy followed by an examination under anesthesia by a colorectal surgeon with seton placement and /or incision and drainage , as indicated . The surgeon was blinded to the initial EUS results of patients in the control group . Medical treatment was maximized with 6-mercaptopurine ( 1.0–1.5 mg/kg ) or azathioprine ( 2.0–2.5 mg/kg ) , ciprofloxacin ( 1,000 mg a day ) or metronidazole ( 1,500 mg a day ) , and infliximab ( 5 mg/kg at 0 , 2 , and 6 wk and then every 8 wk ) . For patients in the control group , additional interventions ( seton removal and repeat surgery ) were at the discretion of the surgeon ( without EUS guidance ) . Patients in the EUS cohort had EUS performed at weeks 22 and 38 , with additional surgical interventions based on EUS findings . The primary end point was complete cessation of drainage at week 54 . All patients had a repeat EUS performed at week 54 to determine the fistula status on EUS ( secondary end point ) . The need for additional surgery was defined as a treatment failure . RESULTS : Ten patients were enrolled in the study . One of 5 ( 20 % ) in the control group and 4 of 5 ( 80 % ) in the EUS group had complete cessation of drainage . From the control group , 3 patients failed due to repeat surgery ( 2 for persistent/recurrent fistula and 1 for abscess ) , and 1 had a persistent drainage at week 54 . In the EUS cohort , 1 patient had a recurrent abscess after his seton fell out prematurely . In the EUS cohort , the median time to cessation of drainage was 99 days , and the time to EUS evidence of fistula inactivity was 229 days . CONCLUSION : This pilot study suggests that using EUS to guide combination medical and surgical therapy for perianal fistulizing Crohn 's disease improves the outcomes Forty‐two patients with a suspected diagnosis of fistula in ano underwent prospect i ve comparison of digital rectal examination , dynamic contrast enhanced magnetic resonance imaging ( DCEMRI ) and surgical exploration . There were five discordancies : DCEMRI showed an ischiorectal abscess and track with no enteric connection in one patient who at operation was found to have a well epithelialized primary fistula . Four patients with fistulas on DCEMRI had no enteric opening found at surgery and were treated as having sinuses . Long‐term follow‐up has shown failure to heal in all patients and further surgery confirmed missed fistula . Compared with final outcome measures DCEMRI had a sensitivity of 97 per cent and specificity of 100 per cent in the detection of fistula . DCEMRI also identified more secondary tracks and was more accurate at identifying complex fistulas than either digital rectal examination alone or surgical exploration OBJECTIVES Objective of the study was to examine patients with fistula preoperatively with MRI  and then compare with operative findings . BACKGROUND Most common cause of perianal suppuration is infection of cryptogl and ular origin . This results in simple intersphincteric abscess , or spreading of infection in cranial or caudal direction , horizontally or circulary . To choose the correct surgical therapy , sufficient diagnostic is necessary . This includes clinical examination , endorectal ultrasonography , rectoscopy with fistula injection with hydrogen peroxide or dye . More and more often MRI is used . METHODS In 2007 19 patients with perianal fistula were operated on . In 14 patients , preoperative MRI was done without contrast dye or probing . Fistulas were classified on 5- grade scale . We treated simple fistulas with fistulectomies , in three cases of complicated fistulas cutting setons were used . RESULTS We examined 14 patients and confronted preoperative MRI result with operative findings . In 12 patients results matched , in two patients peroperatively diagnosed and treated fistula did not show on MRI . One was transsphincteric fistula with abscess and one was simple transsphincteric fistula . Because of low number of patients , statistical interpretations are not significant . CONCLUSIONS Results are preliminary , we continue in prospect i ve analysis . MRI may be useful for successful treatment by correct assessment of the extent of disease . It is necessary to consider cost-effectiveness when indicating MRI ( Tab . 6 , Fig. 3 , Ref . 11 ) . Full Text ( Free , PDF ) www.bmj.sk This study was aim ed at investigating the effectiveness of Magnetic Resonance Imaging ( MRI ) in the diagnosis of perianal fistulas , by comparing imaging findings with those provided by rectal examination ( RE ) or surgery . The present data refer to 20 patients with anorectal fistulas in whom 24 main fistulous tracks were found . The fistulas were classified according to Parks and Kennedy 's criteria , based on their relationship to the sphincters . In the 15 surgical patients , 15 of 17 fistulas were correctly identified by MRI ( 88.2 % ) . In one case the submucous path of the fistula was missed , while another patient was misdiagnosed as having an intersphincter fistula which turned out to be a transphincter one at surgery . In the 5 
    Output:
    
: From the available literature , the summarized performance characteristics for MRI and endoanal ultrasound demonstrate comparable sensitivities at detecting perianal fistulas , although the specificity for MRI was higher than that for endoanal ultrasound .
Both specificity values are considered to be diagnostically poor , however .
The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice .