Improving Vessel Segmentation with Multi-Task Learning and Auxiliary Data Available Only During Model Training.

Liver vessel segmentation in magnetic resonance imaging data is important for the computational analysis of vascular remodeling, associated with a wide spectrum of diffuse liver diseases. Existing approaches rely on contrast enhanced imaging data, but the necessary dedicated imaging sequences are not uniformly acquired. Images without contrast enhancement are acquired more frequently, but vessel segmentation is challenging, and requires large-scale annotated data. We propose a multi-task learning framework to segment vessels in liver MRI without contrast. It exploits auxiliary contrast enhanced MRI data available only during training to reduce the need for annotated training examples. Our approach draws on paired native and contrast enhanced data with and without vessel annotations for model training. Results show that auxiliary data improves the accuracy of vessel segmentation, even if they are not available during inference. The advantage is most pronounced if only few annotations are available for training, since the feature representation benefits from the shared task structure. A validation of this approach to augment a model for brain tumor segmentation confirms its benefits across different domains. An auxiliary informative imaging modality can augment expert annotations even if it is only available during training.

Correlation of histologic, imaging, and artificial intelligence features in NAFLD patients, derived from Gd-EOB-DTPA-enhanced MRI: a proof-of-concept study.

OBJECTIVE: To compare unsupervised deep clustering (UDC) to fat fraction (FF) and relative liver enhancement (RLE) on Gd-EOB-DTPA-enhanced MRI to distinguish simple steatosis from non-alcoholic steatohepatitis (NASH), using histology as the gold standard. MATERIALS AND METHODS: A derivation group of 46 non-alcoholic fatty liver disease (NAFLD) patients underwent 3-T MRI. Histology assessed steatosis, inflammation, ballooning, and fibrosis. UDC was trained to group different texture patterns from MR data into 10 distinct clusters per sequence on unenhanced T1- and Gd-EOB-DTPA-enhanced T1-weighted hepatobiliary phase (T1-Gd-EOB-DTPA-HBP), then on T1 in- and opposed-phase images. RLE and FF were quantified on identical sequences. Differences of these parameters between NASH and simple steatosis were evaluated with χ2- and t-tests, respectively. Linear regression and Random Forest classifier were performed to identify associations between histological NAFLD features, RLE, FF, and UDC patterns, and then determine predictors able to distinguish simple steatosis from NASH. ROC curves assessed diagnostic performance of UDC, RLE, and FF. Finally, we tested these parameters on 30 validation cohorts. RESULTS: For the derivation group, UDC-derived features from unenhanced and T1-Gd-EOB-DTPA-HBP, plus from T1 in- and opposed-phase, distinguished NASH from simple steatosis (p ≤ 0.001 and p = 0.02, respectively) with 85% and 80% accuracy, respectively, while RLE and FF distinguished NASH from simple steatosis (p ≤ 0.001 and p = 0.004, respectively), with 83% and 78% accuracy, respectively. On multivariate regression analysis, RLE and FF correlated only with fibrosis (p = 0.040) and steatosis (p ≤ 0.001), respectively. Conversely, UDC features, using Random Forest classifier predictors, correlated with all histologic NAFLD components. The validation group confirmed these results for both approaches. CONCLUSION: UDC, RLE, and FF could independently separate NASH from simple steatosis. UDC may predict all histologic NAFLD components. CLINICAL RELEVANCE STATEMENT: Using gadoxetic acid-enhanced MR, fat fraction (FF > 5%) can diagnose NAFLD, and relative liver enhancement can distinguish NASH from simple steatosis. Adding AI may let us non-invasively estimate the histologic components, i.e., fat, ballooning, inflammation, and fibrosis, the latter the main prognosticator. KEY POINTS: • Unsupervised deep clustering (UDC) and MR-based parameters (FF and RLE) could independently distinguish simple steatosis from NASH in the derivation group. • On multivariate analysis, RLE could predict only fibrosis, and FF could predict only steatosis; however, UDC could predict all histologic NAFLD components in the derivation group. • The validation cohort confirmed the findings for the derivation group.

[Proctology]. / Proktologie.

This article provides a practice-oriented overview of the most common proctological diseases: Anal eczema, hemorrhoidal disease, anal thrombosis, marisca, anal abscess and fistula, and anal fissure. Definitions and etiopathogenesis, clinic and diagnostics, and current therapy are presented.

Adherence to fast track measures in colorectal surgery-a survey among German and Austrian surgeons.

PURPOSE: The effectiveness of modern perioperative treatment concepts has been demonstrated in several studies and meta-analyses. Despite good evidence, limited implementation of the fast track (FT) concept is still a widespread concern. To assess the status quo in Austrian and German hospitals, a survey on the implementation of FT measures was conducted among members of the German Society of General and Visceralsurgery (DGAV), the German Society of Coloproctology (DGK) and the Austrian Society of Surgery (OEGCH) to analyze where there is potential for improvement. METHODS: Twenty questions on perioperative care of colorectal surgery patients were sent to the members of the DGAV, DGK and OEGCH using the online survey tool SurveyMonkey®. Descriptive data analysis was performed using Microsoft Excel. RESULTS: While some of the FT measures have already been routinely adopted in clinical practice (e.g. minimally invasive surgical approach, early mobilization and diet buildup), for other components there are discrepancies between current recommendations and present implementation (e.g. the use of local nerve blocks to provide opioid-sparing analgesia or the use of abdominal drains). CONCLUSION: The implementation of the FT concept in Austria and Germany is still in need of improvement. Particularly regarding the use of abdominal drains and postoperative analgesia, there is a tendency to stick to traditional structures. To overcome the issues with FT implementation, the development of an evidence-based S3 guideline for perioperative care, followed by the founding of a surgical working group to conduct a structured education and certification process, may lead to significant improvements in perioperative patient care.

Influence of dilution on arterial-phase artifacts and signal intensity on gadoxetic acid-enhanced liver MRI.

OBJECTIVES: To investigate the effect of saline-diluted gadoxetic acid, done for arterial-phase (AP) artifact reduction, on signal intensity (SI), and hence focal lesion conspicuity on MR imaging. METHODS: We retrospectively examined 112 patients who each had at least two serial gadoxetic acid-enhanced liver MRIs performed at 1 ml/s, first with non-diluted (ND), then with 1:1 saline-diluted (D) contrast. Two blinded readers independently analyzed the artifacts and graded dynamic images using a 5-point scale. The absolute SI of liver parenchyma, focal liver lesions (if present), aorta, and portal vein at the level of the celiac trunk and the SI of the paraspinal muscle were measured in all phases. The signal-to-norm (SINorm) of the vascular structures, hepatic parenchyma and focal lesions, and the contrast-to-norm (CNorm) of focal liver lesions were calculated. RESULTS: AP artifacts were significantly reduced with dilution. Mean absolute contrast-enhanced liver SI was significantly higher on the D exams compared to the ND exams. Likewise, SINorm of liver parenchyma was significantly higher in all contrast-enhanced phases except transitional phase on the D exams. SINorm values in the AP for the aorta and in the PVP for portal vein were significantly higher on the diluted exams. The CNorm was not significantly different between ND and D exams for lesions in any imaging phase. The interclass correlation coefficient was excellent (0.89). CONCLUSION: Gadoxetic acid dilution injected at 1ml/s produces images with significantly fewer AP artifacts but no significant loss in SINorm or CNorm compared to standard non-diluted images. KEY POINTS: • Diluted gadoxetic acid at slow injection (1 ml/s) yielded images with higher SINorm of the liver parenchyma and preserved CNorm for focal liver lesions. • Gadoxetic acid-enhanced MRI injected at 1 ml/s is associated with arterial-phase (AP) artifacts in 31% of exams, which may degrade image quality and limits focal liver lesion detection. • Saline dilution of gadoxetic acid 1:1 combined with a slow injection rate of 1 ml/s significantly reduced AP artifacts from 31 to 9% and non-diagnostic AP artifacts from 16 to 1%.

Added value of quantitative, multiparametric 18F-FDG PET/MRI in the locoregional staging of rectal cancer.

PURPOSE: The purpose of this study was to determine whether multiparametric positron emission tomography/magnetic resonance imaging (mpPET/MRI) can improve locoregional staging of rectal cancer (RC) and to assess its prognostic value after resection. METHODS: In this retrospective study, 46 patients with primary RC, who underwent multiparametric 18F-fluorodeoxyglucose (FDG) PET/MRI, followed by surgical resection without chemoradiotherapy, were included. Two readers reviewed T- and N- stage, mesorectal involvement, sphincter infiltration, tumor length, and distance from anal verge. In addition, diffusion-weighted imaging (DWI) and PET parameters were extracted from the multiparametric protocol and were compared to radiological staging as well as to the histopathological reference standard. Clinical and imaging follow-up was systematically assessed for tumor recurrence and death. RESULTS: Locally advanced rectal cancers (LARC) exhibited significantly higher metabolic tumor volume (MTV, AUC 0.74 [95% CI 0.59-0.89], p = 0.004) and total lesion glycolysis (TLG, AUC 0.70 [95% CI 0.53-0.87], p = 0.022) compared to early tumors. T-stage was associated with MTV (AUC 0.70 [95% CI 0.54-0.85], p = 0.021), while N-stage was better assessed using anatomical MRI sequences (AUC 0.72 [95% CI 0.539-0.894], p = 0.032). In the multivariate regression analysis, depending on the model, both anatomical MRI sequences and MTV/TLG were capable of detecting LARC. Combining anatomical MRI stage and MTV/TLG led to a superior diagnostic performance for detecting LARC (AUC 0.81, [95% CI 0.68-0.94], p < 0.001). In the survival analysis, MTV was independently associated with overall survival (HR 1.05 [95% CI 1.01-1.10], p = 0.044). CONCLUSION: Multiparametric PET-MRI can improve identification of locally advanced tumors and, hence, help in treatment stratification. It provides additional information on RC tumor biology and may have prognostic value.

[Anal incontinence]. / Anale Inkontinenz.

Anal incontinence describes the uncontrolled transanal passage of gaseous, solid or liquid intestinal contents. It can be a considerable psychosocial burden and impairment of the quality of life for those affected. The cause can be primary damage to the continence organ or incontinence can be a secondary symptom of other diseases. The detailed patient history and clinical examination document the severity of incontinence, impairment of quality of life and pathomorphological changes. The treatment is primarily conservative. A combination of conservative therapeutic approaches can often achieve satisfactory symptom relief. If conservative treatment remains insufficient, surgical measures can be considered. Sphincteroplasty and sacral neuromodulation are the preferred surgical interventions.

Modern imaging of cholangitis.

Cholangitis refers to inflammation of the bile ducts with or without accompanying infection. When intermittent or persistent inflammation lasts 6 months or more, the condition is classified as chronic cholangitis. Otherwise, it is considered an acute cholangitis. Cholangitis can also be classified according to the inciting agent, e.g. complete mechanical obstruction, which is the leading cause of acute cholangitis, longstanding partial mechanical blockage, or immune-mediated bile duct damage that results in chronic cholangitis.The work-up for cholangitis is based upon medical history, clinical presentation, and initial laboratory tests. Whereas ultrasound is the first-line imaging modality used to identify bile duct dilatation in patients with colicky abdominal pain, cross-sectional imaging is preferable when symptoms cannot be primarily localised to the hepatobiliary system. CT is very useful in oncologic, trauma, or postoperative patients. Otherwise, magnetic resonance cholangiopancreatography is the method of choice to diagnose acute and chronic biliary disorders, providing an excellent anatomic overview and, if gadoxetic acid is injected, simultaneously delivering morphological and functional information about the hepatobiliary system. If brush cytology, biopsy, assessment of the prepapillary common bile duct, stricture dilatation, or stenting is necessary, then endoscopic ultrasound and/or retrograde cholangiography are performed. Finally, when the pathologic duct is inaccessible from the duodenum or stomach, percutaneous transhepatic cholangiography is an option. The pace of the work-up depends upon the severity of cholestasis on presentation. Whereas sepsis, hypotension, and/or Charcot's triad warrant immediate investigation and management, chronic cholestasis can be electively evaluated.This overview article will cover the common cholangitides, emphasising our clinical experience with the chronic cholestatic liver diseases.

Imaging of inflammatory disease of the pancreas.

Increasingly acute and chronic pancreatitis (AP and CP) are considered a continuum of a single entity. Nonetheless, if, after flare-up, the pancreas shows no residual inflammation, it is classified as AP. CP is characterised by a long cycle of worsening and waning glandular inflammation without the pancreas ever returning to its baseline structure or function. According to the International Consensus Guidelines on Early Chronic Pancreatitis, pancreatic inflammation must last at least 6 months before it can be labelled CP. The distinction is important because, unlike AP, CP can destroy endocrine and exocrine pancreatic function, emphasising the importance of early diagnosis. As typical AP can be diagnosed by clinical symptoms plus laboratory tests, imaging is usually reserved for those with recurrent, complicated or CP. Imaging typically starts with ultrasound and more frequently with contrast-enhanced computed tomography (CECT). MRI and/or MR cholangiopancreatography can be used as a problem-solving tool to confirm indirect signs of pancreatic mass, differentiate between solid and cystic lesions, and to exclude pancreatic duct anomalies, as may occur with recurrent AP, or to visualise early signs of CP. MR cholangiopancreatography has replaced diagnostic endoscopic retrograde cholangiopancreatography (ERCP). However, ERCP, and/or endoscopic ultrasound (EUS) remain necessary for transpapillary biliary or pancreatic duct stenting and transgastric cystic fluid drainage or pancreatic tissue sampling, respectively. Finally, positron emission tomography-MRI or positron emission tomography-CT are usually reserved for complicated cases and/or to search for extra pancreatic systemic manifestations. In this article, we discuss a broad spectrum of inflammatory pancreatic disorders and the utility of various modalities in diagnosing acute and chronic pancreatitis.

Enteral resorbable diet versus standard diet in primary sphincter reconstruction: a prospective randomised trial.

AIM: Bowel movements after reconstructive anorectal surgery may negatively affect surgical outcome. This study was aimed to assess any differences between a standard diet (SD) and the enteral resorbable diet (ED) in terms of operative outcomes and patient tolerance after fistulectomy with primary sphincter reconstruction. METHOD: Adult patients undergoing elective fistulectomy with primary sphincter reconstruction for anorectal and rectovaginal fistulas were eligible for inclusion. Patients were intraoperatively randomised to receive either the ED and peristalsis-inhibiting medication (ED) or a SD. The primary endpoint was the healing rate. Secondary endpoints included continence scores, complications and quality of life. Sample size calculation resulted in the analysis of 60 patients to detect a difference in fistula recurrence of 30% with 70% power and a 5% significance level. RESULTS: Sixty-six patients (24 women) were prospectively and randomly assigned to the ED (n = 34: 51%) or a SD (n = 32; 48%); mean age was 47 (18-74) years. The primary healing rate was 64 out of 66 patients (96%). No statistical difference in healing rate was seen between the groups. However, patient satisfaction was significantly higher in the SD group (P < 0.0001). CONCLUSIONS: Fistulectomy with primary sphincter reconstruction is a safe method with low complication rates. Postoperative stool behaviour has no significant influence on the healing rate but has a significant negative impact on patient satisfaction. Therefore, maintaining a standard diet seems to be preferable following reconstructive anal surgery. TRIAL REGISTRATION: The trial was registered with the German Clinical Trials Register ( DRKS00020524 ).

[Standards and New Developments in Proctology]. / Standards und neue Entwicklungen in der Proktologie.

During the last years there was quite a lot of new developments in the international literature. Mostly these were technical methods and instruments. The results were from acceptable improvements to disappointing outcomes. Their focus was haemorrhoidal disease, anorectal fistulas and anal fissures. Despite these new developments all current standards remain on a high level of value.

Quantification of liver function using gadoxetic acid-enhanced MRI.

The introduction of hepatobiliary contrast agents, most notably gadoxetic acid (GA), has expanded the role of MRI, allowing not only a morphologic but also a functional evaluation of the hepatobiliary system. The mechanism of uptake and excretion of gadoxetic acid via transporters, such as organic anion transporting polypeptides (OATP1,3), multidrug resistance-associated protein 2 (MRP2) and MRP3, has been elucidated in the literature. Furthermore, GA uptake can be estimated on either static images or on dynamic imaging, for example, the hepatic extraction fraction (HEF) and liver perfusion. GA-enhanced MRI has achieved an important role in evaluating morphology and function in chronic liver diseases (CLD), allowing to distinguish between the two subgroups of nonalcoholic fatty liver diseases (NAFLD), simple steatosis and nonalcoholic steatohepatitis (NASH), and help to stage fibrosis and cirrhosis, predict liver transplant graft survival, and preoperatively evaluate the risk of liver failure if major resection is planned. Finally, because of its noninvasive nature, GA-enhanced MRI can be used for long-term follow-up and post-treatment monitoring. This review article aims to describe the current role of GA-enhanced MRI in quantifying liver function in a variety of hepatobiliary disorders.

Hybrid imaging of the abdomen and pelvis.

Accurate imaging is crucial for lesion detection in abdominal organs, for the noninvasive characterization of focal and diffuse abnormalities, and for surgical planning. To accomplish these tasks, several imaging modalities such as multidetector computer tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) are used for abdominal imaging, providing important morphological, functional or metabolic information. More recently, PET/MRI has been gaining attention due to the possibility of combining high-resolution imaging with metabolic imaging. PET/MRI is a novel hybrid imaging technology that in the near future might play a pivotal role in the clinical management of oncologic and inflammatory abdominopelvic diseases. Despite the still limited number of published clinical studies, PET/MRI has been proven to be at least equivalent to PET/CT and to standalone MRI in a variety of oncologic disease. Moreover, in selected and focused clinical studies, it has been proven to outperform current standard of care imaging, for example, in evaluating cholangiocarcinomas, liver metastases, untreated and treated rectal cancer. This has also had an impact on therapeuticmanagement in some studies. Therefore in some institutions, including those of the authors, PET/MRI is becoming the new standard imaging modality in staging treatment-naïve intrahepatic massforming cholangiocarcinomas and prior to complicated hepatic surgery.

[Hybrid imaging of the abdomen and pelvis. German version]. / Hybridbildgebung bei abdominellen Erkrankungen.

Accurate imaging is crucial for lesion detection in abdominal organs, for the noninvasive characterization of focal and diffuse abnormalities, and for surgical planning. To accomplish these tasks, several imaging modalities such as multidetector computer tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) are used for abdominal imaging, providing important morphological, functional or metabolic information. More recently, PET/MRI has been gaining attention due to the possibility of combining high-resolution imaging with metabolic imaging. PET/MRI is a novel hybrid imaging technology that in the near future might play a pivotal role in the clinical management of oncologic and inflammatory abdominopelvic diseases. Despite the still limited number of published clinical studies, PET/MRI has been proven to be at least equivalent to PET/CT and to stand-alone MRI in a variety of oncologic disease. Moreover, in selected and focused clinical studies, it has been proven to outperform current standard of care imaging, for example, in evaluating cholangiocarcinomas, liver metastases, untreated and treated rectal cancer. This has also had an impact on therapeutic management in some studies. Therefore in some institutions, including those of the authors, PET/MRI is becoming the new standard imaging modality in staging treatment-naïve intrahepatic mass-forming cholangiocarcinomas and prior to complicated hepatic surgery.

Management of Perianal Fistulas in Crohn's Disease.

BACKGROUND: Perianal fistulizing Crohn's disease is associated with severe symptoms such as pain, fecal incontinence, and a significant reduction in quality of life. RESULTS: In refractory cases, many patients face the decision of having a stoma and/or requiring proctectomy. In former years, the standard of care was a complete fistulectomy, bringing with it a high rate of continence disorders. Additionally, many patients received indefinite treatment, namely the placement of a seton to maintain surgical drainage. CONCLUSION: More recently, newer biologics, cell-based therapies as well as novel surgical techniques have been introduced, raising new hopes that outcomes can be improved upon.

Management of retrorectal supralevator abscess-results of a large cohort.

PURPOSE: Proximal intersphincteric fistulas with proximal extension causing supralevatoric, retrorectal abscesses are a rare disease. There is only very limited experience, with small groups, and the limited published literature confirms the complexity of diagnostics and treatment. The aim of this study was to evaluate transrectal internal abscess drainage as planned definitive treatment. METHODS: We retrospectively studied medical records of all patients with the diagnosis of retrorectal abscesses that underwent transrectal internal abscess drainage in the Department of Colo-proctology of the University Medical Centre Mannheim (2003-2012). RESULTS: One hundred nine patients were operated on retrorectal abscesses, 70 (64.2%) men and 39 (35.8%) women. Mean age was 45.3 years (18-81). In 96 cases (88.1%), only a transrectal internal abscess drainage was performed as planned definitive treatment. Primary healing occurred in 60 patients (62.5%). A second transrectal internal drainage procedure was necessary in 27 cases (28.1%) to assure complete internal drainage. All secondary procedures led to subsequent healing. A combined surgical treatment due to coexisting fistula tracts to the perianal skin or additional ischioanal abscesses was required in 13 patients (11.9%), and an additional seton placement was performed. Nine patients (9.4%) underwent one or more reoperations due to previously unidentified complex coexisting fistulas. Most of these patients were immunosuppressed due to Crohn's disease. Internal drainage alone was successful in 90.6% with an overall healing rate of 94.5% for the entire population of complex fistulas. CONCLUSIONS: Transrectal internal abscess drainage is a safe and highly successful procedure for treatment of retrorectal abscess, with very low risk of postoperative fecal incontinence. Inflammatory bowel disease and immunosuppressives have a negative impact on the healing process.

Fistulectomy with primary sphincter reconstruction.

AIM: Despite modern medical techniques, anatomically proximal (high) anal fistulas are still a challenge in colorectal surgery. In previous years, the standard of care was complete fistulectomy with a high rate of continence disorders. Over the past 20 to 30 years, sphincter-saving procedures have gained wide acceptance. They represent the technique used in these cases. Additionally, many patients received indefinite treatment, namely the placement of a seton to maintain surgical drainage. The main problem with all fistula surgical possibilities is the high recurrence rate of 30 to 50% in flap procedures and 100% persistence in seton treatments. In recent years, a direct repair (primary reconstruction) in distal fistulas was instigated and shows excellent results. It allowed our technique for proximal (high) anal fistulas to evolve. METHOD: All patients who underwent surgery at the University Medical Center Mannheim, Department of Colo-proctology (from 06/2003 to 11/2015), were retrospectively evaluated using a prospective database. Patients who underwent fistulectomy with primary sphincter reconstruction were all included. RESULTS: The primary healing rate, after a mean follow-up of 11 months (7 to 200 months), was 88.2% (374 of 424). Taking into account revisionary surgeries with secondary sphincter repair, this rate reaches 95.8% (406 of 424). Factors such as gender and fistula location as related to the sphincter had significant influence on the study outcome, whereas variables such as the amount of reconstructed muscle (in mm), number of revisions, patient age, other anal operations, and concomitant medication did not. The incontinence of a subgroup of 148 patients was evaluated in detail by way of a questionnaire. Even at a preoperative baseline, 9.6% of those patients reported some minor degree of continence disorders. After the procedure, incontinence disorders were observed in 34 patients (23.0%), with 23 of these patients suffering from flatus incontinence (15.5%), 10 patients from liquid incontinence (6.8%), and 1 patient from solid fecal incontinence. CONCLUSION: Fistulectomy with primary sphincter reconstruction is a feasible procedure resulting in a low recurrence rate. No other procedure has shown better results in transsphincteric fistulas. Continence disorders seem to be of minor relevance/consequence for these patients.

Operative and medical treatment of chronic anal fissures-a review and network meta-analysis of randomized controlled trials.

Anal fissures are a common problem and have a cumulative lifetime incidence of 11%. Previous reviews on anal fissures show inconsistent results regarding post-interventional healing and incontinence rates. In this review our aim was to compare the treatments for chronic anal fissures by incorporating indirect comparisons using network meta-analysis. The PubMed database was searched for randomized controlled trials (RCTs) published between 1975 and 2015. The primary outcome measures were healing and incontinence rates after lateral internal sphincterotomy (LIS), anal dilatation (DILA), anoplasty and/or fissurectomy (FIAP), botulinum toxin (BT) and noninvasive treatment (NIT). Random effects network meta-analyses were complemented by fixed effects and Bayesian models. The present analysis included 44 RCTs and 3268 patients. After a median follow-up of 2 months, the healing rates for LIS, DILA, FIAP, BT and NIT were 93.1, 84.4, 79.8, 62.6, and 58.6% and the incontinence rates were 9.4, 18.2, 4.9, 4.1, and 3.0%, respectively. Compared with NIT, the odds ratio (OR) [95% confidence interval (CI)] for healing after LIS, DILA, FIAP and BT was 9.9 (5.4-18.1), 8.6 (3.1-24.0), 3.5 (1.0-12.7) and 1.9 (1.1-3.5), respectively, on network meta-analysis. The OR (95% CI) for incontinence after LIS, DILA, FIAP and BT was 6.8 (3.1-15.1), 16.9 (6.0-47.8), 3.9 (1.0-15.1) and 1.6 (0.7-3.7), respectively. Ranking of treatments, fixed effects and Bayesian models confirmed these findings. In conclusion, based on our meta-analysis LIS is the most efficacious treatment but is compromised by a high rate of postoperative incontinence. Given the trade-offs between the risks and benefits, FIAP and BT might be good alternatives for the treatment of chronic anal fissures.

German S3 guidelines: anal abscess and fistula (second revised version).

BACKGROUND: The incidence of anal abscess and fistula is relatively high, and the condition is most common in young men. METHODS: This is a revised version of the German S3 guidelines first published in 2011. It is based on a systematic review of pertinent literature. RESULTS: Cryptoglandular abscesses and fistulas usually originate in the proctodeal glands of the intersphincteric space. Classification depends on their relation to the anal sphincter. Patient history and clinical examination are diagnostically sufficient in order to establish the indication for surgery. Further examinations (endosonography, MRI) should be considered in complex abscesses or fistulas. The goal of surgery for an abscess is thorough drainage of the focus of infection while preserving the sphincter muscles. The risk of abscess recurrence or secondary fistula formation is low overall. However, they may result from insufficient drainage. Primary fistulotomy should only be performed in case of superficial fistulas. Moreover, it should be done by experienced surgeons. In case of unclear findings or high fistulas, repair should take place in a second procedure. Anal fistulas can be treated only by surgical intervention with one of the following operations: laying open, seton drainage, plastic surgical reconstruction with suturing of the sphincter (flap, sphincter repair, LIFT), and occlusion with biomaterials. Only superficial fistulas should be laid open. The risk of postoperative incontinence is directly related to the thickness of the sphincter muscle that is divided. All high anal fistulas should be treated with a sphincter-saving procedure. The various plastic surgical reconstructive procedures all yield roughly the same results. Occlusion with biomaterial results in lower cure rate. CONCLUSION: In this revision of the German S3 guidelines, instructions for diagnosis and treatment of anal abscess and fistula are described based on a review of current literature.