Usefulness of magnetic resonance imaging for diagnosing deep anorectal abscesses

Acute supralevator abscess: the little we know

INTRODUCTION

Acute supralevator abscess (SLA) is an uncommon and complicated form of anorectal sepsis. Its correct management is crucial to avoid complex iatrogenic fistula formation. A comprehensive review of the literature was conducted to determine the incidence of SLA and the surgical outcome with particular reference to the direction of drainage.

METHODS

A search of Medline, PubMed and the Cochrane Library was performed to identify all studies reporting surgical drainage of SLA.

FINDINGS

A total of 19 studies were identified, including 563 patients. The only two prospective studies reported an incidence of SLA of 10% and 3% in 68 and 100 patients, respectively, with anorectal sepsis. In 17 retrospective studies, the incidence ranged from 0% to 28%. Magnetic resonance imaging (MRI) was performed routinely in only one study. The surgical anatomical classification of the abscess was described in six studies diagnosed at surgery. The direction of surgical drainage whether 'inwards' (into the lumen) or 'outwards' (into the ischioanal fossa) was stated in only six studies. In two of these, the direction of drainage was contradictory to the recommendation made by Parks et al. Recurrent sepsis was reported in eight studies and ranged from 0% to 53%.

CONCLUSIONS

Detailed and prospective data on acute SLA are lacking. Its real incidence is unclear and it is not possible to analyse surgical outcomes conclusively according to different direction of drainage. The routine use of MRI in complicated anorectal sepsis would specify the surgical anatomy of SLA before any drainage is carried out.

The comparison of CT fistulography and MR imaging of perianal fistulae with surgical findings: a case-control study

PURPOSE

The purpose of this study was to evaluate the diagnostic efficacies of CT fistulography and MRI, in the diagnostic work-up of perianal fistula patients.

MATERIALS AND METHODS

All 41 patients who were included in the study (36 males and 5 females, with an average age of 41 years) underwent CT fistulography and MRI examinations prior to surgery. The fistula characteristics obtained from these examinations were compared with the surgical findings. The comparative results were evaluated by means of the Kappa analysis method.

RESULTS

CT fistulography predicted the correct perianal fistula classification in 30 (73.1%) of the 41 patients, whereas MRI correctly defined fistula classification in 38 (92.7%) of these patients (the K values were 0.621 and 0.896, respectively; with p < 0.001). CT fistulography depicted 29 secondary extensions in 16 patients, whereas MR imaging revealed 28 secondary extensions in 15 patients. A substantial agreement was found between surgical findings and two modalities (K value was 0.789 and 0.793 for CT fistulography and MRI, respectively, with a p value < 0.001). In terms of locations of internal openings, CT fistulography was able to detect the locations in 28 patients (68.2%), whereas MRI was more successful in this aspect, with a number of 35 patients (85.3%). Granulation tissues, inflammation and edema around the fistula, abscesses, and fistular wall fibrosis were also evaluated.

CONCLUSION

CT fistulography and MRI have different advantages in the diagnosis of perianal fistulas. A good command of knowledge concerning the issue may be a key factor in modality decision.

Management of cryptoglandular supralevator abscesses in the magnetic resonance imaging era: a case series

AIM

The aim of this study is to describe the diagnostic performance of magnetic resonance imaging in the management of supralevator abscess, regarding its origin, location, drainage route, subsequent treatment of the fistula, and long-term results.

METHODS

A retrospective case series including thirteen consecutive patients with cryptoglandular supralevator abscess treated between 2001 and 2011 at a colorectal unit of a tertiary referral center. A magnetic resonance imaging was performed in all patients before surgical drainage, and its usefulness in assessing supralevator abscess origin was analyzed. Short- and long-term results after drainage were also evaluated.

RESULTS

The final diagnosis of supralevator abscess and the location described in the magnetic resonance were confirmed intraoperatively in all patients. An ischiorectal origin was identified in nine patients, and perineal translevator drainage was performed placing a mushroom catheter through the ischiorectal or the postanal space. Four patients underwent secondary treatment of anal fistula: two rectal advancement flap and two non-cutting seton. In the other four patients, an intersphincteric origin was identified and transanal surgical drainage was performed placing a long-term mushroom catheter. Several weeks later, transanal unroofing of the residual cavity was performed and the fistula lay open to the anorectal lumen. In the long-term follow-up (median 61 months), only patients with supralevator abscess of ischiorectal origin in whom fistula was not subsequently treated presented a recurrence of the anal sepsis.

CONCLUSIONS

Magnetic resonance imaging seems essential to clarify the location of supralevator abscess, its origin, and choice of the right drainage route. Subsequent treatment of the fistula is necessary to avoid recurrence.

Endosonography and magnetic resonance imaging in the diagnosis of high anal fistulae - a comparison

Anal fistula is a benign inflammatory disease with unclear etiology which develops in approximately 10 in 100 000 adult patients. Surgical treatment of fistulae is associated with a risk of damaging anal sphincters. This usually happens in treating high fistulae, branched fistulae, and anterior ones in females. In preoperative diagnosis of anal fistulae, endosonography and magnetic resonance imaging play a significant role in planning the surgical technique. The majority of fistulae are diagnosed in endosonography, but magnetic resonance is performed when the presence of high fistulae, particularly branched ones, and recurrent is suspected.

THE AIM OF THIS PAPER

The aim of this paper was to compare the roles of the two examinations in preoperative assessment of high anal fistulae.

MATERIAL AND METHODS

The results of endosonographic and magnetic resonance examinations performed in 2011-2012 in 14 patients (4 women and 10 men) with high anal fistulae diagnosed intraoperatively were subject to a retrospective analysis. The patients were aged from 23 to 66 (mean 47). The endosonographic examinations were performed with the use of a BK Medical Pro Focus system with endorectal 3D transducers with the frequency of 16 MHz. The magnetic resonance scans were performed using a Siemens Avanto 1.5 T scanner with a surface coil in T1, T1FS, FLAIR, T2 sequences and in T1 following contrast medium administration. The sensitivity and specificity of endosonography and magnetic resonance imaging were analyzed. A surgical treatment served as a method for verification. The agreement of each method with the surgery and the agreement of endosonography and magnetic resonance imaging were compared in terms of the assessment of the fistula type, localization of its internal opening and branches. The agreement level was determined based on the percentage of consistent assessments and Cohen's coefficient of agreement, κ. The integrity of the anal sphincters was assessed in each case.

RESULTS

In determining the fistula type, magnetic resonance imaging agreed with intraoperative assessment in 79% of cases, and endosonography in 64% of cases. Endosonography agreed with magnetic resonance in 57% of cases. In the assessment of internal opening, the agreement between endosonography and intraoperative assessment was 65%, between magnetic resonance and intraoperative assessment - 41% and between endosonography and magnetic resonance - 53%. In the assessment of fistula branches, endosonography agreed with intraoperative assessment in 67% of cases, magnetic resonance in 87% of cases, and the agreement between the two methods tested was 67%.

CONCLUSIONS

Magnetic resonance is a more accurate method than endosonography in determining the type of high fistulae and the presence of branches. In assessing the internal opening, endosonography proved more accurate. The agreement between the two methods ranges from 53-67%; the highest level of agreement was noted for the assessment of branching.

Recent progress in surgical management of perianal abscess

Perianal abscess is one of the common rectal diseases. Surgical management is still the most effective way. Surgical methods have roughly experienced three phases of landmark development: initially simple incision/drainage combined with surgery for the second time when fistula-in-ano is formed, followed by primary curative incision, and finally sphincter-preserving surgery, which reinforces the importance of protecting the function of the anus. The use of these surgical methods not only reduces the recurrence of abscess and the incidence of anal fistula, but also protects the fine function and integrity of the anus, greatly reducing the pain in patients and raising their quality of lives.

Management of intersphincteric abscesses

OBJECTIVE

Intersphincteric abscesses are relatively rare, and in some cases of upward extensions in the supralevator plane, can be difficult to manage. The aim of this study was to analyse the type of treatment used in these abscesses.

METHODS

Twenty-one intersphincteric abscesses treated by endoanal drainage in our colorectal unit between 1992 and 2004 were reviewed from our database; location and extension of the abscess, type of treatment and recurrence rates and the use of endoanal ultrasound were studied.

RESULTS

Ninety per cent of patients were male; 10 had a previous history of surgery for perianal abscess and suppuration (48%); 16 (76%) had a posterior location and five were anterolateral. Twelve patients had low intersphincteric abscesses and were treated by laying open the abscess and dividing the internal sphincter. Nine were found to have high extensions into the intermuscular planes and were treated by staged procedures: a temporary transanal mushroom catheter was used in seven patients. Endoanal ultrasound was used initially in seven patients (33.3%) and for the evaluation of definitive treatment in 11 (52%).

CONCLUSIONS

Low intersphincteric abscesses should be treated by de-roofing of the abscess and division of the internal sphincter up to a level of the dentate line. High intersphincteric abscesses are relatively frequent and mostly require staged surgery with a temporary mushroom (de Pezzer) catheter. Accurate anatomical ultrasound localization and proper drainage become important to avoid recurrences or extrasphincteric fistulas.

Perianal Crohn's disease and infliximab therapy

INTRODUCTION

Perianal manifestations occur in almost half of patients with Crohn's disease and often respond poorly to conventional therapies. The introduction of anti-tumour necrosis factor alpha agents (e.g. infliximab) has altered the management of patients who fail first and second line medical and surgical therapies.

METHODS

We performed a literature search of the PubMed database using the Medical Search Headings infliximab, perianal Crohn's disease, fistulae, cost and safety. We also performed a manual search using references from these articles, review articles and proceedings from major gastroenterology meetings.

RESULTS

Use of infliximab, at a dose of 5mg/kg at intervals of 0, 2 and 6 weeks, results in significant improvement in disease in approximately 70% of patients with fistulae. Prior examination under anaesthesia with placement of non-cutting seton sutures in fistula tracks is a useful adjunct in many patients. Preliminary results show a benefit from maintenance infliximab therapy and from concomitant use of immunosuppressants such as azathioprine. No clinical or biochemical markers have been identified which predict non-response to infliximab, although its use is contraindicated in patients with strictures. Acute infusion reactions are the most common side-effect of infliximab therapy and they are usually mild. Despite initial fears, the incidence of opportunistic infection is low. There is inadequate information, at present, regarding a possible increase in incidence of lymphoma with infliximab therapy. Infliximab is expensive compared with established therapies and its use will increase the lifetime cost of treating Crohn's disease.

CONCLUSION

While infliximab is a useful adjunct in selected patients, the cornerstones of management of perianal Crohn's are essentially unchanged.

Topical L-arginine gel lowers resting anal pressure: possible treatment for anal fissure

PURPOSE

Exogenous nitric oxide donors, such as glyceryl trinitrate, have been used as treatment for anal fissures; however, headaches develop in 60 percent of patients. Nitric oxide produced from the cellular metabolism of L-arginine mediates relaxation of the internal anal sphincter. This study investigated whether topical L-arginine gel reduces maximum anal resting pressure in volunteers.

METHOD

In a two-center study, volunteers received a single topical dose of L-arginine or placebo (Aquagel ). Anal manometry was performed for two hours after application of 400 mg of L-arginine gel or placebo gel to the anal verge in 25 volunteers. Side effects were recorded after single application and also after repeated dosing for three days.

RESULTS

L-Arginine reduced maximum anal resting pressure by 46 percent from a median of 65 cm of water to a minimal value of 35 cm of water ( P< 0.001, Wilcoxon's signed-rank test). The difference between L-arginine and placebo using repeated-measures testing was significant at P< 0.005. No side effects occurred with either gel; in particular, no episodes of headache were recorded.

CONCLUSION

Topical L-arginine gel significantly lowers maximum anal resting pressure; its onset of action is rapid, and duration is at least two hours ( P< 0.01). L-arginine may have therapeutic potential, but further evaluation is needed before it can be used as a possible alternative treatment for chronic anal fissure.

Endosonography of anal canal diseases

Anal endosonography became a valuable imaging method for diagnosis of anal diseases because of its accessibility, relative simplicity of performance, and low cost. It is used most often to detect anal sphincter defects, to classify anal fistulas and perianal abscesses, and to stage anal tumors. This review presents a normal anatomy of the anal canal, examination technique, and normal endosonographic anatomy of anal sphincters. The endosonographic findings of anal sepsis, malignancy, trauma, abnormalities in Crohn disease, and ulcerative colitis, as well as the role for anal endosonography among other imaging modalities, are discussed.