P J Tozer

What role do bacteria play in persisting fistula formation in idiopathic and Crohn's anal fistula?

The aetiology of Crohns disease‐related anal fistula remains obscure. Microbiological, genetic and immunological factors are thought to play a role but are not well understood. The microbiota within anal fistula tracts has never been examined using molecular techniques. The present study aimed to characterize the microbiota in the tracts of patients with Crohns and idiopathic anal fistula.

Natural history of anorectal sepsis

Progression from anorectal abscess to fistula is poorly described and it remains unclear which patients develop a fistula following an abscess. The aim was to assess the burden of anorectal abscess and to identify risk factors for subsequent fistula formation.

Volume assessment magnetic resonance imaging technique for monitoring perianal Crohn’s fistulas:

Background: Perianal Crohn’s fistula and their response to anti-tumour necrosis factor (TNF) therapies are best assessed with magnetic resonance imaging (MRI), but radiologist reporting is subjective and variable. This study investigates whether segmentation software could provide precise and reproducible objective measurements of fistula volume. Methods: Retrospective analysis of patients with perianal Crohn’s fistula at our institution between 2007 and 2013. Pre- and post-biologic MRI scans were used with varying time intervals. A total of two radiologists recorded fistula volumes, mean signal intensity and time taken to measure fistula volumes using validated Open Source segmentation software. A total of three radiologists assessed fistula response to treatment (improved, worse or unchanged) by comparing MRI scans. Results: A total of 18 cases were reviewed for this pilot study. Inter-observer variability was very good for volume and mean signal intensity; intra-class correlation (ICC) 0.95 [95% confidence interval (CI) 0.91–0.98] and 0.95 (95% CI 0.90–0.97) respectively. Intra-observer variability was very good for volume and mean signal intensity; ICC 0.99 (95% CI 0.97–0.99) and 0.98 (95% CI 0.95–0.99) respectively. Average time taken to measure fistula volume was 202 s and 250 s for readers 1 and 2. Agreement between three specialist radiologists was good [kappa 0.69 (95% CI 0.49–0.90)] for the subjective assessment of fistula response. Significant association was found between objective percentage volume change and subjective consensus agreement of response (pu2004=u20040.001). Median volume change for improved, stable or worsening fistula response was −67% [interquartile range (IQR): −78, −47], 0% (IQR: −16, +17), and +487% (IQR: +217, +559) respectively. Conclusion: Quantification of fistula volumes and signal intensities is feasible and reliable, providing an objective measure of perianal Crohn’s fistula and response to treatment.

P446 Patient and public involvement in a clinical trial for perianal Crohn’s fistula

the two groups. Patients with active fistulas had significantly more work impairment (median 0.20 vs. 0.10, p = 0.010). Furthermore, patients with active fistulas held more negative views concerning the effects of their illness on daily functioning (adjusted β = 0.78; CI(95%) = 0.28 to 1.27 (95% CI), p = 0.003). No differences were found in coping strategies between the two groups. Conclusions: Patients with active perianal fistulas have a lower physical health, experience more work impairment and perceived more illness consequences compared with CD patients without perianal fistulas, which is important for the gastroenterologist to consider when treating these patients. Reference 1. van Erp SJ et al. Classifying back pain and peripheral joint complaints in inflammatory bowel disease patients: a prospective longitudinal follow-up study. J Crohns Colitis, 2016;10:166–175.

High take-off intussusception or prolapse may have a poor outcome after standard ventral mesh rectopexy—a tailored approach is required

We read with interest the report by Tsunoda et al. [1] on the presence and impact of new-onset rectoanal intussusception following ventral mesh rectopexy for rectal prolapse. Proponents argue that laparoscopic ventral mesh rectopexy (LVMR) is a safe and effective treatment for rectal prolapse and intussusception, correcting anatomical abnormality and reducing symptoms of obstructive defecation [2], even in the long term [3]. Complications include (synthetic) mesh erosion into the vagina or rectum (Fig. 1) which is distressing but increasingly uncommon, falling from 10% in an early systematic review [4] to around 3% more recently [2]. Failure remains a significant problem, and in particular, the occurrence of new-onset rectoanal or rectorectal intussusception is associated with reduced symptomatic improvement after surgery [1, 5]. We believe a specific group of patients treated with LVMR are at higher risk of failure for this reason. LVMR relies on dissection anterior to the rectum, avoiding lateral or posterior dissection and therefore injury to the inferior and superior hypogastric plexuses, respectively. It is postulated that this autonomic nerve preservation accounts for the avoidance of constipation after surgery. However, in high take-off prolapse or intussusception, anterior dissection and fixation alone will not address laxity in the posterior rectum and the posterior rectal wall can intussuscept within or through the segment which has only been supported anteriorly and distal to the take-off point. This ‘new-onset intussusception’ really represents a failure to address the existing intussusception posteriorly and above the site of mesh placement and probably leads to the persistence of the presenting symptoms of obstructive defecation. We postulate that posterior dissection with fixation of the mesorectum to the sacral promontory (by whichever method) should address the high take-off component and can be performed alongside ventral mesh rectopexy which itself adds value where additional support in the rectovaginal septum is needed, for example in the case of combined rectocele and intussusception leading to obstructive defecation. It is our view that the optimal technique for symptomatic and anatomical correction of intussusception and prolapse will include a range of different elements, tailored to the particular anatomical pathology of a given patient. A ‘one-size-fits-all’ approach does not recognise these subgroups, and failure will ensue in some patients. A prognostic and therapeutic classification is needed to describe the range of pathology and to aid selection of the most appropriate technique. & P. J. Tozer philtozer@doctors.org.uk

P307 The clinical course of rectovaginal fistulas in Crohn's disease since the introduction of anti TNF drugs

P306 Efficacy and safety of low-molecular weight heparin for the prevention of venous thromboembolism in patients with severe ulcerative colitis A. Papa1 *, A. Armuzzi2, L. Guidi3, I. De Vitis4, G. Mocci5, C. Felice4, M. Marzo6, D. Pugliese1, G.L. Rapaccini7. 1Catholic University of Rome, Internal Medicine and Gastroenterology Complesso Integrato Columbus, Rome, Italy, 2Complesso Integrato Columbus, Gastroenterology Unit, Rome, Italy, 3Universita Cattolica Del Sacro Cuore, O.U. Gastroenterology Columbus, Rome, Italy, 4Universita Cattolica Del Sacro Cuore, Complesso integrato Columbus/OU of Internal Medicine and Gastroenterology, Rome, Italy, 5Catholic University of Rome, Internal Medicine Gastroenterology, Rome, Italy, 6Complesso Integrato Columbus, Medicina Interna e Gastroenterologia, Rome, Italy, 7Catholic University of Rome, Complesso Integrato Columbus/OU of Internal Medicine and Gastroenterology, Rome, Italy