Endoscopic ultrasound for perianal Crohn's disease: disease and fistula characteristics, and impact on therapy

Interventional inflammatory bowel disease: current and future practice

PURPOSE OF REVIEW

Inflammatory bowel diseases (IBD) are associated with several well described neoplastic and structural complications. Increasing disease prevalence, healthcare barriers, and medication refractory phenotypes contribute to ongoing complications despite significant strides in medical management. Enhancements in endoscopic technology and techniques have allowed a minimally invasive approach for what has historically required surgery. In this article, we review the current and future landscape of endoscopic IBD intervention.

RECENT FINDINGS

Endoscopic resection is the first line for managing conventional and complex colitis-associated dysplasia. Evidence supporting endoscopic submucosal dissection is mounting, yet there is a paucity of studies evaluating modified endoscopic mucosal resection techniques or hybrid endoscopic submucosal dissection. We also have more clarity in how best to approach fibrostenotic disease, as we learn how to position endoscopic stricturotomy and stenting, relative to balloon dilation. Finally, applications in managing penetrating and postsurgical complications have been described, but still require further study.

SUMMARY

While important knowledge gaps still exist, the application of endoscopic therapies in IBD is more refined, especially within the management of colitis-associated dysplasia and strictures. The indications for endoscopy in perianal disease and other penetrating manifestations of Crohn's disease presents exciting opportunities for growth.

Mesenchymal stem cell therapy for therapy refractory complex Crohn's perianal fistulas: a case series

BACKGROUND

Mesenchymal stem cell treatment (MST) has emerged as a new therapeutic strategy for Crohn's perianal fistulas. It has been demonstrated that a fibrotic tract on MRI with a MAGNIFI-CD score ≤ 6 is the best predictor for long-term clinical closure. Therefore, the aim of the current study was to analyse the effectiveness of MST for complex Crohn's perianal fistulas based on MRI.

METHODS

Consecutive patients with complex Crohn's perianal fistulas, previously failing both anti-TNF treatment and surgical closure, who had surgical closure of the internal opening with MST were included. The primary endpoint was radiological remission of the fistula(s) defined as a MAGNIFI-CD ≤ 6 on MRI, read by an experienced radiologist.

RESULTS

Between December 2019 and March 2023, 30 patients (15 males) with 48 fistula tracts were included with a median follow-up of 16.5 months. Radiological remission was achieved in thirteen patients (43.3%) after a median follow-up of 5.0 months (IQR 3.0-6.0). The median MAGNIFI-CD at baseline was 15.0 (IQR 7.0-20.0) which significantly decreased to 8.0 (IQR 3.0-15.0) after treatment (p = 0.001). Clinical closure was achieved in 21 patients (70.0%). Three patients (14.3%) developed a recurrence during long-term FU, all with clinically closed fistula(s), but no radiological remission. The median PDAI decreased significantly from 10.5 (IQR 7.0-14.0) to 4.0 (IQR 0.0-7.3) (p = 0.001).

CONCLUSION

MST is a promising treatment strategy for therapy refractory Crohn's perianal fistulas, resulting in > 40% radiological remission, clinical closure in 70% and a significant improvement in quality of life. No recurrences were seen in patients with radiological remission.

Disease- and Medication-Specific Differences of the Microbial Spectrum in Perianal Fistulizing Crohn's Disease-Relevant Aspects for Antibiotic Therapy

Perianal fistulizing Crohn's Disease (CD) with abscess formation represents an aggressive phenotype in Inflammatory Bowel Disease (IBD) with increased morbidity. Treatment is multidisciplinary and includes antibiotics, but knowledge about the microbial spectrum is rare often resulting in inadequate antimicrobial therapy. In this single center retrospective study, all patients who were operated due to perianal abscess formation were retrospectively analyzed and the microbial spectrum evaluated. Patients were divided into a CD and non-CD group with further subgroup analysis. 138 patients were finally included in the analysis with 62 patients suffering from CD. Relevant differences were detected for the microbial spectrum with anaerobic bacteria being significantly more often isolated from non-CD patients. In a subgroup-analysis of CD patients only, medical therapy had a relevant effect on the microbial spectrum since Streptococcus groups and Enterobacterales were significantly more often isolated in patients treated with steroids compared to those being treated by antibodies. In conclusion, the microbial spectrum of patients suffering from CD varies significantly from non-CD patients and immunosuppressive medication has a relevant effect on isolated pathogens. Based on that, adaption of antibiotic treatment might be discussed in the future.

Imaging Evaluation of Inflammatory Bowel Disease Complications

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that can progress to fibrostenotic and penetrating complications. Cross-sectional imaging is often needed for accurate diagnosis of IBD complication and for planning the appropriate management strategy. Computed tomography enterography, magnetic resonance enterography, and IBD ultrasound have become key tools for clinicians and interventional endoscopists. This article highlights and discusses various radiologic imaging techniques and their application to the diagnosis and management of IBD complications.

Endoscopic Evaluation and Management of Perianal Disease

Perianal Crohn's disease is associated with decreased quality of life, high morbidity, and high health care use. Treatment goals are to provide infection control, stop fistula drainage, and heal fistula tracts while preserving the anorectal sphincter. Treatment includes a combination of medical and surgical intervention, but new techniques are using interventional endoscopy to act as either a bridge to surgery or to decrease the need for surgical intervention. The decision on which approach to pursue requires knowledge of prior surgery, altered anatomy, prior fistula treatment, and imaging and endoscopic evaluation of fistula complexity, mucosal involvement, and associated stricture or abscess.

Establishing a rabbit model of perianal fistulizing Crohn’s disease

BACKGROUND

Crohn's disease (CD) is a chronic nonspecific intestinal inflammatory disease. The aetiology and pathogenesis of CD are still unclear. Anal fistula is the main complication of CD and is a difficult problem to solve at present. The main limitation of developing new therapies is bound up with the short of preclinical security and effectiveness data. Therefore, an ideal animal model is needed to establish persistent anal fistula and an inflamed rectal mucosa.

AIM

To improve the induction method of colitis and establish a reliable and reproducible perianal fistulizing Crohn’s disease animal model to evaluate new treatment strategies.

METHODS

Twenty male New Zealand rabbits underwent rectal enema with different doses of 2,4,6-trinitrobenzene sulfonic acid to induce proctitis. Group A was treated with an improved equal interval small dose increasing method. The dosage of group B was constant. Seven days later, the rabbits underwent surgical creation of a transsphincteric fistula. Then, three rabbits were randomly selected from each group every 7 d to remove the seton from the fistula. The rabbits were examined by endoscopy every 7 days, and biopsy forceps were used to obtain tissue samples from the obvious colon lesions for histological analysis. The disease activity index (DAI), colonoscopy and histological scores were recorded. Perianal endoscopic ultrasonography (EUS) was used to evaluate the healing of fistulas.

RESULTS

Except for the DAI score, the colonoscopy and histological scores in group A were significantly higher than those in group B (P < 0.05). In the ideal model rabbit group, on the 7^th day after the removal of the seton, all animals had persistent lumens on EUS imaging, showing continuous full-thickness high signals. Histological inspection of the fistula showed acute and chronic inflammation, fibrosis, epithelialization and peripheral proctitis of the adjoining rectum.

CONCLUSION

The improved method of CD colitis induction successfully established a rabbit perianal fistula CD preclinical model, which was confirmed by endoscopy and pathology.

Evaluation of animal models of Crohn's disease with anal fistula (Review)

Anal fistula is a common and serious complication of Crohn's disease (CD). A sufficiently suitable animal model that may be used to simulate this disease is yet to be established. The aim of the present review was to summarize the different characteristics and experimental methods of commonly used animal models of CD with anal fistula. Electronic databases were searched for studies reporting on the use of this type of animal model. A total of 234 related articles were retrieved, of which six articles met the inclusion criteria; these were used as references for the present review article. The characteristics of the animal models, the advantages and disadvantages of the modeling methods and the similarities with patients with CD and anal fistula were summarized and analyzed. The evidence suggests that a sufficiently suitable animal preclinical model requires to be established.

Mucinous adenocarcinoma arising from recurrent perianal fistula in patient with Crohn's disease: case report

Introduction Anal carcinoma is a rare variant of epithelial tumors of the anal canal. When associated with chronic and active anal fistulas, usually this is an aggressive cancer that has difficult diagnosis and poor prognosis. Anal fistulas are a common manifestation of Crohn's disease (CD). This study aims to report a case of mucinous adenocarcinoma originating from recurrent perianal fistula in patients with CD.

Case report A man of 43 years, with melanoderma, complaining of perianal tumors, anal pain and mucopurulent secretion, the patient was diagnosed with fistulae. Colonoscopy revealed a chronic inflammatory process associated with villous polypoid lesion in the colonic and rectal mucosa. In a new episode, where it was diagnosed, chronic colitis of rectum and sigmoid was being prescribed sulfasalazine with improvement. There were relapses and the patient underwent repeated fistulectomias. After investigation, CD was diagnosed. Computed tomography (CT) of abdomen and pelvis showed multiple perineal and gluteal collections, and the patient underwent abdominoperineal resection of the rectum. Anatomopathological exam showed invasive mucinous adenocarcinoma. A new CT showed residual growth of the lesion. The patient was referred to the oncology referral service, where chemotherapy and radiotherapy were planned. The patient developed unfavorably, and his death occurred two months after treatment.

Evaluation of a Seton Procedure Combined With Infliximab Therapy (Early vs. Late) in Perianal Fistula With Crohn Disease

PURPOSE

We assessed the clinical outcomes of a seton procedure combined with early versus late institution of infliximab (IFX) therapy.

METHODS

This retrospective study comprised 76 patients who underwent surgery for perianal fistula associated with Crohn disease between January 2014 and November 2017. All patients underwent loose seton drainage combined with IFX therapy. Patients categorized as the early group (EG, 49 patients) received IFX therapy within 30 days of completion of the seton procedure. Patients categorized as the late group (LG, 27 patients) received IFX therapy >30 days after the seton procedure. IFX therapy was administered as induction and maintenance therapy.

RESULTS

There were no statistically significant intergroup differences in clinical characteristics of the patients. The mean follow-up was 21.0 ± 11.6 months in the EG and 34.5 ± 18.4 months in the LG (P = 0.001). The mean interval between seton procedure and IFX induction therapy was 12.2 days in the EG and 250.2 days in the LG (P = 0.002). Complete remission was observed in 32 patients (65.3%) in the EG and 17 patients (63.0%) in the LG (P = 0.844). Fistula recurrence was observed in 6 patients (7.9%). All recurrences occurred in a previous perianal fistula tract.

CONCLUSION

Patients showed a good response to a seton procedure combined with IFX therapy regardless of the time of initiation of IFX therapy.

EFSUMB Recommendations for Gastrointestinal Ultrasound Part 3: Endorectal, Endoanal and Perineal Ultrasound

This article represents part 3 of the EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound (GIUS). It provides an overview of the examination techniques recommended by experts in the field of endorectal/endoanal ultrasound (ERUS/EAUS), as well as perineal ultrasound (PNUS). The most important indications are rectal tumors and inflammatory diseases like fistula and abscesses in patients with or without inflammatory bowel disease (IBD). PNUS sometimes is more flexible and convenient compared to ERUS. However, the technique of ERUS is quite well established, especially for the staging of rectal cancer. EAUS also gained ground in the evaluation of perianal diseases like fistulas, abscesses and incontinence. For the staging of perirectal tumors, the use of PNUS in addition to conventional ERUS could be recommended. For the staging of anal carcinomas, PNUS can be a good option because of the higher resolution. Both ERUS and PNUS are considered excellent guidance methods for invasive interventions, such as the drainage of fluids or targeted biopsy of tissue lesions. For abscess detection and evaluation, contrast-enhanced ultrasound (CEUS) also helps in therapy planning.

Burden and outcomes for complex perianal fistulas in Crohn's disease: Systematic review

AIM

To systematically review the literature on epidemiology, disease burden, and treatment outcomes for Crohn's disease (CD) patients with complex perianal fistulas.

METHODS

PubMed, Embase, and Cochrane were searched for relevant articles (published 2000-November 2016) and congress abstracts (published 2011-November 2016).

RESULTS

Of 535 records reviewed, 62 relevant sources were identified (mostly small observational studies). The cumulative incidence of complex perianal fistulas in CD from two referral-centre studies was 12%-14% (follow-up time, 12 years in one study; not reported in the second study). Complex perianal fistulas result in greatly diminished quality of life; up to 59% of patients are at risk of faecal incontinence. Treatments include combinations of medical and surgical interventions and expanded allogeneic adipose-derived stem cells. High proportions of patients experience lack of or inadequate response to treatment (failure and relapse rates, respectively: medical, 12%-73% and 0%-41%; surgical: 0%-100% and 11%-20%; combined medical/surgical: 0%-80% and 0%-50%; stem cells: 29%-47% and not reported). Few studies (1 of infliximab; 3 of surgical interventions) have been conducted in treatment-refractory patients, a population with high unmet needs. Limited data exist on the clinical value of anti-tumour necrosis factor-α dose escalation in patients with complex perianal fistulas in CD.

CONCLUSION

Complex perianal fistulas in CD pose substantial clinical and humanistic burden. There is a need for effective treatments, especially for patients refractory to anti-tumour necrosis factor-α agents, as evidenced by high failure and relapse rates.

Papel da ultrassonografia endoscópica na avaliação da fístula perianal na doença de Crohn

RESUMO Objetivo: determinar o papel da ultrassonografia endoscópica (UE) em relação à ressonância magnética nuclear (RMN) e ao exame sob anestesia (ESA) no manejo de pacientes com doença de Crohn fistulizante perianal. Métodos: estudo observacional transversal com pacientes com doença de Crohn perianal, avaliados em um centro terciário de Curitiba, Paraná, Brasil, de fevereiro de 2016 a março de 2017. Todos os pacientes foram submetidos à UE, RMN e ESA. O grau de concordância entre os três métodos foi avaliado através da obtenção do coeficiente de Kappa. Um valor de Kappa de 0,7 ou maior indicou boa concordância. O teste não paramétrico de Friedman foi utilizado para comparar o número de trajetos fistulosos detectados em cada modalidade. Considerou-se o nível de significância estatística como p<0,05. Resultados: vinte pacientes foram incluídos. Houve concordância entre os três exames em 11 pacientes. O nível de concordância de Kappa entre os três exames foi 0,53 (moderado) (p<0,001). Não houve diferença estatisticamente significativa em relação ao número de trajetos fistulosos detectados nos três exames (p=0,641). Houve falha na identificação de um trajeto fistuloso em três pacientes com a UE, em três pacientes com a RMN e em dois pacientes com o ESA. Conclusão: a UE foi comparável à RMN e ao ESA para avaliação da doença de Crohn fistulizante perianal, e pode ser considerada um exame válido para investigação pré-operatória desses pacientes.

Present status and perspectives of endosonography 2017 in gastroenterology

Endoscopic ultrasound has become an essential tool in modern gastroenterology and abdominal surgery. Compared with all other endoscopic methods, it has the most potential for innovation and its future looks bright. Thus, we compiled this summary of established and novel applications of endoscopic ultrasound methods to inform the reader about what is already possible and where future developments will lead in improving patient care further. This review is structured in four parts. The first section reports on developments in diagnostic endoscopic ultrasound, the second looks at semi-invasive endoscopic ultrasound, and the third discusses advances in therapeutic endoscopic ultrasound. An overview on the future prospects of endoscopic ultrasound methods concludes this article.

Prognostic factors affecting outcomes in fistulating perianal Crohn's disease: a systematic review

BACKGROUND

One in three patients with Crohn's disease will develop a perianal fistulae, and one third of these will achieve long-term healing or closure. A barrier to conducting well-designed clinical trials for these patients is a lack of understanding of prognostic factors. This systematic review sets out to identify factors associated with prognosis of perianal Crohn's fistulae.

METHODS

This review was registered on the PROSPERO database (CRD42016050316) and conducted in line with PRISMA guidelines along a predefined protocol. English-language studies assessing baseline factors related to outcomes of fistulae treatment in adult patients were included. Searches were performed on MEDLINE and Embase databases. Screening of abstracts and full texts for eligibility was performed prior to extraction of data into predesigned forms. Bias was assessed using the QUIPS tool.

RESULTS

Searches identified 997 papers. Following removal of duplicates and secondary searches, 923 were screened for inclusion. Forty-seven papers were reviewed at full-text level and 13, 2 of which were randomised trials, were included in the final qualitative review. Two studies reported distribution of Crohn's disease as a prognostic factor for healing. Two studies found that CARD15 mutations decreased response of fistulae to antibiotics. Complexity of fistulae anatomy was implicated in prognosis by 4 studies.

CONCLUSIONS

This systematic review has identified potential prognostic markers, including genetic factors and disease behaviour. We cannot, however, draw robust conclusions from this heterogeneous group of studies; therefore, we recommend that a prospective cohort study of well-characterised patients with Crohn's perianal fistulae is undertaken.

Exploring endoscopic therapy for the treatment of Crohn's disease-related fistula and abscess

Fistula and abscess represent penetrating disease phenotypes of Crohn's disease (CD) and can develop in patients with or without prior history of CD-related surgery. While CD fistula and abscess have been traditionally treated with medical and surgical therapy, the role of endoscopic therapy in this particular phenotype of CD is expanding recently, thanks to advanced endoscopic techniques and a better understanding of pathogenesis and natural history of the disease and principle of treatment. The success of endoscopic treatment for inflammatory bowel disease depends on comprehension and appreciation of principles, then techniques, followed by instrument and device. Attempts should be made to temporarily or permanently close the feeding side (or the primary) orifice at the gut, by various forms of clipping. Endoscopic fistulotomy is feasible, particularly for perianal fistula and surgery-associated distal bowel fistula. Perianal abscess can be treated with endoscopic incision and drainage and even seton placement. Endoscopic treatment for fistula and abscess as well as for stricture has become an important part of the multidisciplinary approach to complex CD.

The Gastroenterologist's Role in Management of Perianal Fistula

Perianal fistula occurs frequently in the Crohn disease population. Therapy for fistulas has changed through the years from primarily surgical management to multidisciplinary management among gastroenterologists, radiologists, and surgeons. Gastroenterologists play a role in assisting with diagnosis through endoscopic ultrasound and assessment of luminal disease activity, providing medical therapy including biologic therapy and antibiotics, and coordinating the multidisciplinary care with surgical and radiologic colleagues.

Imaging of perianal fistulizing Crohn's disease

Perianal fistula is a complication of Crohn's disease that carries a high morbidity. It is a channel that develops between the lower rectum, anal canal and perianal or perineal skin. The development of perianal fistulas typically connotes a more aggressive disease phenotype and may warrant escalation of treatment to prevent poor outcomes over time. Based on fistula anatomy, debris can form inside these tracts and cause occlusion, which subsequently leads to abscess formation, fever and malaise. The clinical presentation is often with complaints of pain, continuous rectal drainage of fecal matter as well as malodorous discharge. Considering that the presence of fistulas often indicates refractory and aggressive disease, early identification of its presence is important. Some patients may not have the classic symptoms of fistulizing disease at presentation and others may have significant scarring and/or pain from previous fistulizing episodes, which can make an accurate assessment on physical exam alone problematic. As a result, utilizing diagnostic imaging is the best means of identifying the early signs of perianal fistulas or abscess formation in these patients. Several imaging modalities exist which can be used for diagnosis and management. Endoscopic ultrasound and pelvic MRI are considered the most useful in establishing the diagnosis. However, a combination of multiple imaging modalities and/or examination under anesthesia is probably the most ideal. Incomplete characterization of the fistula tract(s) extent or the presence of abscess carries a high morbidity and far-reaching personal expense for the patient - promoting worsening of the disease.

Monitoring disease activity and progression in Crohn's disease. A Swiss perspective on the IBD ahead 'optimised monitoring' recommendations

BACKGROUND AND AIMS

The structured IBD Ahead 'Optimised Monitoring' programme was designed to obtain the opinion, insight and advice of gastroenterologists on optimising the monitoring of Crohn's disease activity in four settings: (1) assessment at diagnosis, (2) monitoring in symptomatic patients, (3) monitoring in asymptomatic patients, and (4) the postoperative follow-up. For each of these settings, four monitoring methods were discussed: (a) symptom assessment, (b) endoscopy, (c) laboratory markers, and (d) imaging. Based on literature search and expert opinion compiled during an international consensus meeting, recommendations were given to answer the question 'which diagnostic method, when, and how often'. The International IBD Ahead Expert Panel advised to tailor this guidance to the healthcare system and the special prerequisites of each country. The IBD Ahead Swiss National Steering Committee proposes best-practice recommendations adapted for Switzerland.

METHODS

The IBD Ahead Steering Committee identified key questions and provided the Swiss Expert Panel with a structured literature research. The expert panel agreed on a set of statements. During an international expert meeting the consolidated outcome of the national meetings was merged into final statements agreed by the participating International and National Steering Committee members - the IBD Ahead 'Optimized Monitoring' Consensus.

RESULTS

A systematic assessment of symptoms, endoscopy findings, and laboratory markers with special emphasis on faecal calprotectin is deemed necessary even in symptom-free patients. The choice of recommended imaging methods is adapted to the specific situation in Switzerland and highlights the importance of ultrasonography and magnetic resonance imaging besides endoscopy.

CONCLUSION

The recommendations stress the importance of monitoring disease activity on a regular basis and by objective parameters, such as faecal calprotectin and endoscopy with detailed documentation of findings. Physicians should not rely on symptoms only and adapt the monitoring schedule and choice of options to individual situations.

Endoscopic treatment of Crohn's complications

The progression to fistula and strictures is part of the natural history of Crohn's disease (CD) and these complications negatively affect the quality of life of CD patients. Surgery is the traditional treatment of CD strictures. However, due the chronicity of the inflammatory process and the associated fibrosis, postoperative recurrence occurs frequently. The lack of specific drug to treat fibrotic strictures and their irreversible nature has drawn the attention to less invasive and bowel-sparing therapeutic modalities. Endoluminal therapies may provide effective option in relieving symptoms associated with CD complications and reduce the need for repeated surgery with substantial clinical benefit. This review will discuss the current use and efficacy of the endoscopic treatment of CD complications. New endoscopic modalities and recent advances will be also evaluated.

Transperineal ultrasonography for evaluation of the perianal fistula and abscess in pediatric Crohn disease: preliminary study

PURPOSE

To assess the feasibility and effectiveness of transperineal ultrasonography (TPUS) for the evaluation of perianal Crohn disease (PCD) in pediatric patients.

METHODS

Between September 2010 and August 2013, 64 TPUS examinations were performed in 43 patients (34 males and 9 females; mean age±standard deviation, 13.3±2.4 years; age range, 6 to 17 years) to evaluate PCD. The pain severity, location, and activity of perianal fistula, the presence of an abscess, and anal canal hyperemia were retrospectively evaluated. Spearman rank correlation analysis was performed to assess the relationship between the severity of the pain and the fistula activity, the presence of an abscess, and anal canal hyperemia.

RESULTS

All examinations were successfully performed. Thirty-nine examinations (60.9%) were performed without any pain experienced by the patient, 19 examinations (29.7%) with mild pain, five examinations (7.8%) with moderate pain, and one examination (1.6%) with severe pain. The pain severity was correlated with the fistula activity (P<0.01). An anterior fistula location was more common than a posterior location. Active fistulas and abscesses were identified during 30 examinations (46.9%) and 12 examinations (18.8%), respectively. Anal canal hyperemia was identified in 31 examinations (48.4%).

CONCLUSION

TPUS with a color Doppler study is useful for visualizing a perianal fistula or abscess and for assessing its inflammatory activity in pediatric Crohn patients.

Transperineal perineal ultrasound versus magnetic resonance imaging in the assessment of perianal Crohn's disease

BACKGROUND

To assess the accuracy of transperineal ultrasound (TPUS), in comparison with magnetic resonance imaging (MRI), in classifying perianal Crohn's disease (CD) according to Parks' classification and the American Gastroenterological Association criteria.

METHODS

Fifty-nine consecutive patients with confirmed or suspected perianal CD underwent TPUS and MRI within 10 days. An independent expert surgical evaluation, which took into account proctological and MRI findings, was used as the gold standard. Fistulae and perianal disease were classified according to Parks' classification and American Gastroenterological Association criteria, respectively.

RESULTS

Forty-six patients showed 64 fistulae (9 intersphincteric, 34 transsphincteric, 2 suprasphincteric, 9 extrasphincteric, and 10 anovaginal) and 23 abscesses were also found. Fifty-one of 54 perianal fistulae (per-lesion sensitivity: 94.4%) and 9 of 10 anovaginal fistulae (sensitivity: 90.0%) were detected and 58 were correctly classified by TPUS (sensitivity: 90.6%; positive predictive value: 93.4%). Overall, TPUS correctly detected and classified the fistulae in 89% of patients and the agreement for classifying perianal fistulae between TPUS and MRI was excellent (K value: 0.783). In contrast, 11 of 23 abscesses were correctly diagnosed by TPUS (sensitivity: 47.8%); although 14 abscesses were diagnosed by TPUS, only 11 were confirmed by MRI (positive predictive value: 78.6%). Overall, TPUS correctly detected and classified fistulae and associated abscesses in 67.3% of patients. Agreement between MRI and TPUS in discriminating simple (15) and complex (29) perianal disease was fairly good (K value: 0.57).

CONCLUSIONS

TPUS is a simple and accurate diagnostic method for classifying perianal fistulae in CD and could be used for the preliminary assessment and follow-up of perianal CD.