The cryptoglandular theory revisited

Antibiotic Treatment Has No Influence on Anal Fistula Formation and Recurrent Perianal Abscess After Incision and Drainage of Cryptogenic Perianal Abscess: A Randomized Single-Blinded Prospective Study

BACKGROUND

Anal fistula commonly appears after incision and drainage of a perianal abscess. Theoretically, a fistula develops as a consequence of the infection process. Antibiotic treatment was suggested to decrease the possibility of fistula development.

OBJECTIVE

We hypothesized that antibiotic treatment has no influence on the development of anal fistula after surgical treatment of perianal abscess.

DESIGN

A single-blinded randomized prospective study.

SETTINGS

Patients with primary cryptogenic abscesses were eligible to participate.

PATIENTS

Patients were divided into 2 groups. Patients in group I received amoxicillin 875 mg/clavulanic acid 125 mg during 7 days after surgery, and patients in group II received no antibiotics. The study database included demographics and clinical and laboratory data.

MAIN OUTCOME MEASURES

Patients were examined in our outpatient clinic 2 weeks, 4 months, and 1 year after surgery, and a telephone questionnaire was performed 6 months after surgery. The primary outcome was the formation of anal fistula. The secondary outcome was recurrent perianal abscess.

RESULTS

Overall, 98 patients completed the study. Groups were not different in inclusion. Anal fistula was diagnosed in 16 patients (16.3%) in group I (treatment group) and 10 patients (10.2%) in group II (control group; p = 0.67). Nine patients (9.2%) developed recurrent perianal abscess, 4 in the treatment group and 5 in the control group ( p = 0.73).

LIMITATIONS

A relatively small number of patients were treated in a single medical center.

CONCLUSION

Antibiotic therapy has no influence on anal fistula or recurrent perianal abscess formation after incision and drainage of perianal abscess. See Video Abstract .

EL TRATAMIENTO CON ANTIBITICOS NO TIENE INFLUENCIA EN LA FORMACIN DE FSTULA ANAL Y EN EL ABSCESO PERIANAL RECURRENTE DESPUS DE LA INCISIN Y DRENAJE DE UN ABSCESO PERIANAL CRIPTOGNICO UN ESTUDIO PROSPECTIVO ALEATORIZADO, SIMPLE CIEGO

ANTECEDENTES:La fístula anal comúnmente aparece después de la incisión y drenaje de un absceso perianal. Teóricamente, la fístula se desarrolla como consecuencia del proceso infeccioso. Se sugirió tratamiento antibiótico para disminuir la posibilidad de desarrollo de fístula.OBJETIVO:Hipotetizamos que el tratamiento con antibióticos no tiene influencia en el desarrollo de fístula anal después del tratamiento quirúrgico del absceso perianal.DISEÑO:Estudio prospectivo, aleatorio, simple ciego.AJUSTE Y PACIENTES:Los pacientes con absceso criptogénico primario fueron elegibles para participar. Los pacientes se dividieron en dos grupos. Los pacientes del Grupo I recibieron amoxicilina 875 mg/ácido clavulánico 125 mg durante los 7 días posteriores a la cirugía y los pacientes del Grupo II no recibieron antibióticos. La base de datos del estudio incluyó datos demográficos, clínicos y de laboratorio.PRINCIPALES MEDIDAS DE RESULTADO:Los pacientes fueron examinados en nuestra clínica ambulatoria 2 semanas, cuatro meses y 1 año después de la cirugía y se realizó un cuestionario telefónico 6 meses después de la cirugía. El resultado primario fue la formación de una fístula anal. El resultado secundario fue el absceso perianal recurrente.RESULTADOS:En total, 98 pacientes completaron el estudio. Los grupos no fueron diferentes en cuanto a la inclusión. Se diagnosticó fístula anal en 16 (16,3%) pacientes del Grupo I (grupo de tratamiento) y 10 (10,2%) pacientes del Grupo II (grupo control) (p = 0,67). Nueve pacientes (9,2%) desarrollaron absceso perianal recurrente, 4 en el grupo de tratamiento y 5 en el grupo control (p = 0,73).LIMITACIONES:Número relativamente pequeño de pacientes tratados en un solo centro médico.CONCLUSIÓN:La terapia con antibióticos no tuvo influencia sobre la fístula anal o la formación de absceso perianal recurrente después de la incisión y drenaje del absceso perianal. (Traducción - Dr. Fidel Ruiz Healy ).

European Society of Coloproctology: Guidelines for diagnosis and treatment of cryptoglandular anal fistula

AIM

The primary aim of the European Society of Coloproctology (ESCP) Guideline Development Group (GDG) was to produce high-quality, evidence-based guidelines for the management of cryptoglandular anal fistula with input from a multidisciplinary group and using transparent, reproducible methodology.

METHODS

Previously published methodology in guideline development by the ESCP has been replicated in this project. The guideline development process followed the requirements of the AGREE-S tool kit. Six phases can be identified in the methodology. Phase one sets the scope of the guideline, which addresses the diagnostic and therapeutic management of perianal abscess and cryptoglandular anal fistula in adult patients presenting to secondary care. The target population for this guideline are healthcare practitioners in secondary care and patients interested in understanding the clinical evidence available for various surgical interventions for anal fistula. Phase two involved formulation of the GDG. The GDG consisted of 21 coloproctologists, three research fellows, a radiologist and a methodologist. Stakeholders were chosen for their clinical and academic involvement in the management of anal fistula as well as being representative of the geographical variation among the ESCP membership. Five patients were recruited from patient groups to review the draft guideline. These patients attended two virtual meetings to discuss the evidence and suggest amendments. In phase three, patient/population, intervention, comparison and outcomes questions were formulated by the GDG. The GDG ratified 250 questions and chose 45 for inclusion in the guideline. In phase four, critical and important outcomes were confirmed for inclusion. Important outcomes were pain and wound healing. Critical outcomes were fistula healing, fistula recurrence and incontinence. These outcomes formed part of the inclusion criteria for the literature search. In phase five, a literature search was performed of MEDLINE (Ovid), PubMed, Embase (Ovid) and the Cochrane Database of Systematic Reviews by eight teams of the GDG. Data were extracted and submitted for review by the GDG in a draft guideline. The most recent systematic reviews were prioritized for inclusion. Studies published since the most recent systematic review were included in our analysis by conducting a new meta-analysis using Review manager. In phase six, recommendations were formulated, using grading of recommendations, assessment, development, and evaluations, in three virtual meetings of the GDG.

RESULTS

In seven sections covering the diagnostic and therapeutic management of perianal abscess and cryptoglandular anal fistula, there are 42 recommendations.

CONCLUSION

This is an up-to-date international guideline on the management of cryptoglandular anal fistula using methodology prescribed by the AGREE enterprise.

Contemporary management of anorectal fistula

Anorectal fistula is a common, chronic condition, and is primarily managed surgically. Herein, we provide a contemporary review of the relevant etiology and anatomy anorectal fistula, treatment recommendations that summarize relevant outcomes and alternative considerations, in particular when to refer to a fistula expert.

Postoperative packing of perianal abscesses following incision and drainage

A best evidence topic in general surgery was written according to a structured protocol, to address the question: in adult patients with perianal abscesses, should postoperative wound packing be undertaken considering the rates of pain experienced, wound healing and abscess recurrence? The literature search identified 159 papers on Ovid, Embase and Medline and 48 on PubMed. These were independently screened, and three articles were included in this review as these offered the best information to answer the question. One was a systematic review without meta-analysis, one was a randomised controlled trial and one was a multicentre observational study. Review of these articles led the authors to conclude that routine postoperative packing of perianal abscesses following incision and drainage is costly, associated with increased pain and confers no protection against recurrence of abscesses or formation of fistulae.

The potential roles of gut microbiome in anal fistula

Anal fistula is a common proctological disease, but the thorough mechanisms of the anal fistula formation are still unclear. An increasing number of studies have revealed the crucial role of gut microbiota in intestinal diseases. We used 16S rRNA gene sequencing to analyze the intestinal microbiome in order to determine whether there are differences in the microbiome between anal fistula patients and healthy individuals. The microbiome samples were extracted by repeatedly wiping the rectal wall with intestinal swab. Before this operation, the whole intestine of all participants was irrigated and the score of the Boston bowel preparation scale reached 9. The biodiversity of gut microbiome of rectum revealed significant difference between anal fistula patients and healthy individuals. 36 discriminative taxa were identified by LEfSe analysis between two groups. At the phylum level, Synergistetes was enriched in anal fistula patients, while Proteobacteria was higher in healthy individuals. We also found that at the genus level, Blautia, Faecalibacterium, Ruminococcus, Coprococcus, Bacteroides, Clostridium, Megamonas and Anaerotruncus were highly enriched in anal fistula patients, while the microbiome of healthy individuals was enriched with Peptoniphilus and Corynebacterium. Spearman correlations showed the extensive and close association among genera and species. Finally, a diagnostic prediction model was constructed by random forest classifier, and the area under curve (AUC) reached 0.990. This study gave an important hint for analyzing gut microbiome of rectum in anal fistula patient.Keypoints.We use the 16S rRNA gene sequencing to test the microbiome samples extracted from the intestinal swab. This is the first study to explore the gut microbiome of rectum using this workflow. We also found the distinct gut microbiome of rectum differences between anal fistula patients and healthy individuals.

Anti TNF treatment of complex perianal fistulas in children without luminal Crohn's disease: Is it an option?

OBJECTIVES

Complex perianal fistulas (CPFs) in children even in the absence of luminal symptoms prompt evaluation for Crohn's disease (CD). Reports of isolated CPF in children, however, are sparse. In perianal CD, antitumor necrosis factor α (anti TNF) therapy is recommended. We aimed to describe our experience with anti TNF therapy in children with isolated CPF without evidence of luminal CD.

METHODS

We retrospectively reviewed charts of patients with isolated CPF who were treated with anti TNF agents between 2011 and 2019 in a tertiary center. MRI pelvis findings at baseline versus end of follow up were scored using MAGNIFI-CD. Outcomes included clinical remission, radiological response and radiological remission based on MAGNIFI-CD score at end of follow up.

RESULTS

Overall, 17 patients were identified, [10 males (59%), mean age at anti TNF initiation 13.4 ± 2.9 years]. Median time from perianal disease onset to anti TNF was 16.5 months (IQR 9.4-36.4). None of the patients had luminal inflammation. Prior to anti TNF, all patients had been treated with antibiotics without sufficient improvement, and 9/17 with abscess drainage and or Seton insertion. Nine patients (53%) were treated with infliximab while 8 (47%) received adalimumab. Median duration of follow up was 30.7 months (IQR = 12.7-44.8). At the end of follow up 9 patients (53%) achieved clinical remission. When comparing MRI prior to and after anti TNF, 36% (5/14) had radiologic response, of whom 2 (14%) achieved radiologic resolution.

CONCLUSION

Anti TNF agents may be an effective treatment option for children with isolated CPF. Whether these patients should be considered part of the CD phenotypic spectrum or a distinct entity is unclear.

LEVELS OF EVIDENCE

Therapeutic.

Benign Anorectal Disorder Management in Low-Resource Settings

There are many benign anorectal disorders, which can make patients seek care. In low-resource settings, the incidence of those pathologies is not different from the industrialized and western world. However, an interesting difference colorectal surgeons and gastroenterologists can face is the fact that many patients do not seek help or are not aware and have little opportunities to be helped. Latin America population is estimated to be around 8% of the world population, with Brazil having the largest percentage. Infectious diseases, which were previously under control or were steadily declining, have emerged. For example, we have seen resurgence of dengue, malaria, and syphilis in pregnancy, as well as other sexually transmitted diseases that can affect the anorectal region. In this article, we will address the most common benign anorectal disorders.

Treatment of cryptoglandular fistulas with the fistula tract laser closure (FiLaC™) method in comparison with standard methods: first results of a multicenter retrospective comparative study in the Netherlands

BACKGROUND

Current surgical closure techniques for sphincter-sparing treatment of high cryptoglandular fistulas in the Netherlands include the mucosal advancement flap procedure (MAF) and ligation of the intersphincteric fistula tract (LIFT). A relatively novel treatment is the fistula tract laser closure (FiLaC™) method. The aim of this study was to investigate the differences in healing and recurrence rates between FiLaC™ and current standard practices.

METHODS

This multicenter retrospective cohort study included both primary and recurrent high cryptoglandular anorectal fistulas, treated with either FiLaC™ or standard methods (MAF or LIFT) between September 2015 and July 2020. Patients with extrasphincteric fistulas, Crohn's disease, multiple fistulas, age < 18 years or missing data regarding healing time or recurrence were excluded. The primary outcomes were the clinical primary and secondary healing and recurrence rates. Primary healing was defined as a closed external opening without fluid discharge within 6 months of treatment on examination, while secondary healing was the same endpoint after secondary treatment. Secondary outcomes included healing time and complaints.

RESULTS

A total of 162 high fistulas from 3 Dutch hospitals were included. Ninety-nine high fistulas were treated with FiLaC™ and 63 with either MAF or LIFT. There were no significant differences between FiLaC™ and MAF/LIFT in terms of clinical healing (55.6% versus 58.7%, p = .601), secondary healing (70.0% versus 69.2%, p = .950) or recurrence rates (49.5% versus 54%, p = .420), respectively. Median follow-up duration was 7.1 months in the FiLaC™ group (interquartile range [IQR] 4.1-14.4 months) versus 6 months in the control group (IQR 3.5-8.1 months).

CONCLUSIONS

FiLaC™ treatment of high anorectal fistulas does not appear to be inferior to MAF or LIFT. Based on these preliminary results, FiLaC™ can be considered as a worthwhile treatment option for high cryptoglandular fistulas. Prospective studies with a longer follow-up period and well-determined postoperative parameters such as complication rates, magnetic resonance imaging for confirmation of fistula healing, incontinence and quality of life are warranted.

Sphincter-Preserving Fistulectomy Is an Effective Minimally Invasive Technique for Complex Anal Fistulas

Background

The optimal treatment of complex anal fistulas remains unclear, though many different sphincter-preserving procedures have been described. A minimally invasive technique with a better outcome is desired. The purpose of this study was to present a new technique—sphincter-preserving fistulectomy (SPF) and its clinical outcomes.

Materials and Methods

A retrospective study was performed to compare the efficacy and outcomes of SPF with ligation of the intersphincteric fistula tract (LIFT) in the management of complex anal fistulas in regards to postoperative pain, complications, wound healing time, recurrence, overall success rate, fecal continence function, and quality of life. Continence function was evaluated using the Wexner incontinence scale and anal manometry. The fecal incontinence quality of life (FIQL) scale was used to assess patients' quality of life.

Results

From June 2020 to July 2021, 41 patients with 43 SPF procedures and 35 patients with 35 LIFT procedures were included. Postoperative pain was comparable between two groups. The morbidity rate and the mean wound healing time in the SPF group were lower than those in the LIFT group (2.3% vs. 48.6%, p < 0.001; 1.4 ± 0.3 vs. 1.7 ± 0.4 months, p = 0.001). At a mean follow-up duration of 11.4 ± 3.5 months in the SPF group and 10.7 ± 4.3 months in the LIFT group, SPF achieved a better overall success rate than LIFT (97.7% vs. 77.1%, p = 0.014). Three patients in the SPF group and 4 patients in the LIFT group who all underwent a simultaneous fistulotomy procedure complained new incontinence of flatus. There was no statistical difference between the two groups in regards to the Wexner scores (p = 0.790), the maximum resting anal canal pressure (p = 0.641), the maximum squeeze pressure (p = 0.289), and the FIQL scores including lifestyle (p = 0.188), coping (p = 0.188), depression (p = 0.850), and embarrassment (p = 0.910).

Conclusions

SPF is a novel, safe, and effective minimally invasive technique for the management of complex anal fistulas, with a promising success rate and negligible impairment on continence. Future prospective studies are needed to evaluate the long-term outcomes of SPF.

Differences in amino acid and lipid metabolism distinguish Crohn's from idiopathic/cryptoglandular perianal fistulas by tissue metabonomic profiling and may offer clues to underlying pathogenesis

INTRODUCTION

Few studies have investigated perianal fistula etiopathogenesis, and although the cryptoglandular theory is widely accepted in idiopathic cases, in Crohn's disease, it is thought to involve the interplay between microbiological, immunological and genetic factors. A pilot study was conducted to assess for metabolic variations in Crohn's perianal fistula tissue that might differ from that of idiopathic (cryptoglandular) perianal fistula tissue as a comparator. The goal was to identify any potential biomarkers of disease, which may improve the understanding of pathogenesis.

AIMS AND METHODS

Fistula tract biopsies were obtained from 30 patients with idiopathic perianal fistula and 20 patients with Crohn's anal fistula. Two different assays were used in an ultra-high-performance liquid chromatography system coupled with a mass spectrometric detector to achieve broad metabolome coverage. Univariate and multivariate statistical data analyses were used to identify differentiating metabolic features corresponding to the perianal fistula phenotype (i.e. Crohn's disease vs. idiopathic).

RESULTS

Significant orthogonal partial least squares discriminant analysis predictive models (validated with cross-validated-analysis of variance P value <0.05) differentiated metabolites from tissue samples from Crohn's vs. idiopathic anal fistula patients using both metabolic profiling platforms. A total of 41 metabolites were identified, suggesting alterations in pathways, including amino acid, carnitine and lipid metabolism.

CONCLUSION

Metabonomics may reveal biomarkers of Crohn's perianal fistula. Further work in larger numbers is required to validate the findings of these studies as well as cross-correlation with microbiome work to better understand the impact of host-gut/environment interactions in the pathophysiology of Crohn's and idiopathic perianal fistulas and identify novel therapeutic targets.

Diagnostic Features of Perianal Fistula in Patients With Crohn's Disease: Analysis of a Japanese Claims Database

Background

Perianal fistula (PAF) is a disabling complication of Crohn's disease (CD) which greatly impacts the quality of life. To address a scarcity of data in Asian populations, we determined the prevalence of CD-associated PAF in Japan, the order of diagnosis, and medical history of patients.

Methods

A retrospective, longitudinal, observational cohort study was conducted, using an employer-based health insurance claims database. The study included patients diagnosed with CD and/or PAF from October 2013 to September 2019.

Results

The age- and gender-adjusted prevalence rates of CD-associated PAF increased from 10.33 per 100 000 in 2014, to 13.68 per 100 000 in 2019. Among patients with CD-associated PAF, 15.7% were diagnosed with PAF after diagnosis of CD, 68.6% were diagnosed with PAF before diagnosis with CD, and 15.7% were diagnosed with CD and PAF within the same month. Of the patients diagnosed with CD after PAF, approximately 30% were diagnosed with PAF by the age of 20 years, whereas less than 10% of PAF patients without CD were diagnosed with PAF by the age of 20 years.

Conclusions

The study reveals the prevalence of CD-associated PAF in Japan and that most individuals were diagnosed with CD after the diagnosis of PAF. Crohn's disease may be underdiagnosed in patients with PAF; patients diagnosed with PAF at a young age should be monitored to allow timely diagnosis of CD.

Intra-abdominal and Anorectal Abscesses

Intra-abdominal and anorectal abscesses are common pathologies seen in both inpatient and outpatient settings. To decrease morbidity and mortality, early diagnosis and treatment are essential. After adequate drainage via a percutaneous or incisional approach, patients need to be monitored for worsening symptoms or recurrence and evaluated for the underlying condition that may have contributed to abscess formation.

Chemical Ablation for Treating Anal Fistulas without Surgical Intervention: Long-Term Results

Purposes. This study aimed to evaluate long-term outcomes after the application of a corrosive chemical agent for ablation of epithelial tissue as a non-surgical treatment of anal fistulas. Methods. Adult patients with symptomatic perianal fistula were prospectively included in the study. The fistula tract was irrigated with a 5% silver nitrate solution. The primary outcome measured in this study was the rate of clinical healing after long-term follow-up. Factors that may affect healing were also analysed. Results. A total of 186 patients with anal fistula were analysed. After irrigation with silver nitrate, 82 (44%) patients had complete clinical healing during a median follow-up time of 50 (7-64) months. Patients with intermittent discharge had a significantly higher rate of complete clinical healing than those with continuous discharge (P < .04). Fistulas without abscesses or secondary tracts had a significantly higher rate of complete clinical healing than the other types (P = .007). Conclusion. Chemical ablation of the epithelium of the anal fistula yields promising long-term outcomes in the management of anal fistulas without surgical intervention.

Prevalence of anal fistula in the United Kingdom

BACKGROUND

Anal fistula is a pathological connection between the anal canal and perianal skin, which most commonly develops from an infected anal crypt. While the majority of anal fistulas are idiopathic, they are also associated with Crohn’s disease (CD) and other inflammatory conditions. The prevalence of anal fistula is estimated to be 1-2 per 10000 patients, but population-based studies on anal fistula epidemiology are limited and outdated.

AIM

To assess the prevalence of anal fistula and relevant comorbidities, with and without CD in the United Kingdom and Europe.

METHODS

A retrospective population-representative observational cohort study was performed in The Health Improvement Network (THIN), a United Kingdom primary care database. Mid-year point prevalence of anal fistula was calculated on the first of July for each year between 2014 and 2017. Estimates were calculated for anal fistula overall and by CD status and standardized to the United Kingdom and European population. Prevalence of relevant comorbidities including lymphogranuloma venereum, hidradenitis suppurativa, anal presentation of sexually transmitted diseases, diabetes mellitus, and radiation in the pelvic area was reported.

RESULTS

The United Kingdom-standardized overall point prevalence of anal fistula was 1.80 (95%CI: 1.65-1.94) per 10000 patients in 2017, while the Europe standardized estimate was 1.83 (95%CI: 1.68-1.98) per 10000 patients. Both these standardized point prevalence estimates ranged from 1.89 to 2.36 between 2014-2016. The United Kingdom-standardized point prevalence of anal fistula without CD was 1.35 (95%CI: 1.23-1.48) per 10000 patients, while the Europe-standardized estimate was 1.39 (95%CI: 1.26-1.52) per 10000 patients. In contrast, the standardized point prevalence estimate of anal fistula with CD was lower for both United Kingdom and Europe (0.44; 95%CI United Kingdom: 0.37-0.52, 95%CI Europe: 0.37-0.51) per 10000 patients in 2017. In 2017, 19% of anal fistula patients without CD and 13% of anal fistula patients with CD had at least one relevant comorbidity. These results show that anal fistulas are infrequent in the general population. 24.5% of prevalent anal fistulas are associated with CD, but other potentially etiological comorbidities are rare.

CONCLUSION

This real-world evidence study estimated the United Kingdom-standardized prevalence of anal fistula was 1.80 per 10000 patients in 2017. Approximately 25% of cases may be associated with CD, while other comorbidities are rare.

Perianal sepsis: surgical perspective and practical MRI reporting for radiologists

This article describes the development of a structured MRI reporting template and diagrammatic worksheet for perianal sepsis through collaboration between radiologists and colorectal surgeons at our institution, and the rationale behind each component of the worksheet. Benefits of this reporting worksheet include optimizing communication of key imaging findings that have a real impact on patient management, less time spent on reporting the study, and easier comparison between studies. We illustrate the utility of the report template with case studies. We summarize the current surgical approaches to perianal sepsis to help radiologists focus on reporting the findings relevant to surgical planning.

Influence of adjuvant antibiotics on fistula formation following incision and drainage of anorectal abscesses: a systematic review protocol

BACKGROUND

Development of fistula-in-ano following incision and drainage (I&D) of anorectal abscesses occurs in over 30% of patients. It is associated with significant patient morbidity and societal cost. The use of antibiotics following drainage is controversial, with randomized controlled trials reporting opposing conclusions regarding their influence on the rate of fistula formation. Given the significant burden associated with their development, it is imperative to determine strategies to minimize their occurrence. The objective of this review is to summarize the available evidence on the role of antibiotics following I&D of anorectal abscesses on fistula formation. Secondary objectives include determining if antibiotics are associated with morbidity, repeat presentation to the emergency department, and requirement for reoperation.

METHODS/DESIGN

MEDLINE, EMBASE, CINAHL, Cochrane Central Registry of Controlled Trials, http://apps.who.int/trialsearch , and clinicaltrials.gov will be searched to identify published and ongoing unpublished interventional and observational studies evaluating the role of antibiotics post I&D on the incidence of fistula formation. There will be no restriction on language, date, or journal. Title and abstracts as well as full texts will be screened in duplicate based on inclusion and exclusion criteria. The Cochrane Risk of Bias tool and ROBINS-I will be used to assess risk of bias in randomized and non-randomized studies, respectively. Our primary outcome is the incidence of fistula formation; secondary outcomes include morbidity, representation to ED, and reoperation. Study heterogeneity will be calculated with Cochran's Q test, P value, and I 2 index. SASS (version 9.4) will be used for meta-analysis.

DISCUSSION

This is the first study to review the available evidence on adjuvant antibiotics and incidence of fistula formation following I&D of anorectal abscesses.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018092044.

Diagnostic accuracy of faecal calprotectin in patients with active perianal fistulas

Background

Faecal calprotectin (FC) is a marker of mucosal inflammation.

Objective

The aim of this study was to determine the diagnostic accuracy of FC to (a) differentiate between perianal fistulizing Crohn's disease (pCD) and cryptoglandular perianal fistulas; and (b) detect mucosal inflammation in pCD.

Methods

Patients with active perianal fistulas who had FC measured and a complete ileocolonoscopy within 10 weeks were retrospectively included.

Results

Fifty-six patients were included (pCD, n = 37) of whom 19 pCD patients exhibited ulcers. FC was significantly higher in pCD compared to cryptoglandular fistulas (µg/g) (708.0 (207.0-1705.0) vs 32.0 (23.0-77.0), p < 0.001). Area-under-the-curve (AUC) value for FC receiver operating characteristic (ROC) statistics was 0.900. Optimal FC cut-off was ≥ 150 µg/g. To differentiate pCD from cryptoglandular fistulas in the absence of luminal inflammation, optimal cut-off remained ≥ 150 µg/g (AUC = 0.857, sensitivity = 0.81, specificity = 0.89, positive predictive value (PPV) = 93.8% and negative predictive value (NPV) = 70.8%). In pCD, FC was significantly increased in the presence of ulcers (1672.0 vs 238.0, p = 0.004). Optimal cut-off was ≥ 250 µg/g (AUC = 0.776; sensitivity = 0.89, specificity = 0.56, PPV - 68.0% and NPV = 83.0%).

Conclusion

FC discriminates pCD from cryptoglandular fistulas, even in the absence of intestinal ulcers. In active pCD, an elevated FC does not accurately predict the presence of ulcers and should be interpreted with caution.