Magnetic resonance imaging in the management of anal fistula and anorectal sepsis

A magnetic resonance imaging-based decision-making tool for predicting complex anal fistulas healing in the early postoperative period

BACKGROUND

Magnetic resonance imaging (MRI) has excellent accuracy in diagnosing preoperative lesions before anal fistula surgery. However, MRI is not good in identifying early recurrent lesions and effective methods for quantitative assessment of fistula healing are still warranted. This retrospective study aimed to develop and validate a specific MRI-based nomogram model to predict fistula healing during the early postoperative period.

METHODS

Patients with complex cryptoglandular anal fistulas who underwent surgery between January 2017 and October 2020 were included in this study. MRI features and clinical parameters were analyzed using univariate and multivariate logistic regression analysis. A nomogram for predicting fistula healing was constructed and validated.

RESULTS

In total, 200 patients were included, of whom 186 (93%) were male, with a median age of 36 (18-65) years. Of the fistulas, 58.5% were classified as transsphincteric and 19.5% as suprasphincteric. The data were randomly divided into the training cohort and testing cohort at a ratio of 7:3. Logistic analysis revealed that CNR, ADC, alcohol intake history, and suprasphincteric fistula were significantly correlated with fistula healing. These four predictors were used to construct a predictive nomogram model in the training cohort. AUC was 0.880 and 0.847 for the training and testing cohorts, respectively. Moreover, the decision and calibration curves showed high coherence between the predicted and actual probabilities of fistula healing.

CONCLUSIONS

We developed a predictive model and constructed a nomogram to predict fistula healing during the early postoperative period. This model showed good performance and may be clinically utilized for the management of anal fistulas.

Modified Van Assche magnetic resonance imaging-based score for assessing the clinical status of anal fistulas

The modified Van Assche magnetic resonance imaging (MRI)-based score is a feasible system to assess the clinical status of anal fistulas in Crohn disease. In this study, we evaluated this score's association with clinical status in patients with anal fistulas (AFs).We included all patients with AF who underwent contrast-enhanced pelvic MRI and surgery between January 2011 and December 2016. The score was evaluated retrospectively preoperatively and 1, 3, and 6 months postoperatively. Univariate and multivariate analyses of the risk factors for AF recurrence were also performed.We retrospectively analyzed data for 104 patients. Twelve (11.5%) patients developed AF recurrence. We classified patients' preoperative clinical status into three grades: 52 (50.0%) grade A, 31 (29.8%) grade B, and 21 (20.2%) grade C. The preoperative MRI-based score was significantly correlated with patients' preoperative clinical status grade (Pearson correlation: 0.547; P < .001). The 3 preoperative clinical status grades showed significant (F = 23.303, P < .001) tendencies for associations with lower respective MRI-based scores. The incidence of AF recurrence decreased with the MRI-based score to 1-month postoperatively, then gradually increased (F = 60.863, P = .000). Long duration of disease, prior interventions, and high MRI-based score were independent risk factors for AF recurrence.The MRI-based score objectively assessed the clinical status and disease activity of patients with AFs, with a high score being associated with severe clinical status and long recovery time.

Perianal sepsis in neutropaenic patients with haematological malignancies: the role of magnetic resonance imaging and surgery

BACKGROUND

Perianal sepsis occurs in up to 10% of neutropaenic patients with haematological malignancy and is associated with significant morbidity and mortality. The management of this condition is challenging in neutropaenic patients due to its atypical pathophysiology. The aim of this study is to assess the role of magnetic resonance imaging (MRI) and surgery in neutropaenic patients with perianal sepsis.

METHODS

A retrospective chart review was performed on all neutropenic patients with a haematological malignancy who had a diagnosis of perianal sepsis during the inpatient admission between 2008 and 2017. Patient characteristics, symptoms, haematological data, MRI result, surgical intervention, intraoperative findings and outcomes including recurrence and mortality were collected.

RESULTS

Nineteen neutropaenic patients with haematological malignancy were treated for perianal sepsis, eight (42%) patients were managed conservatively and 11 (58%) were managed surgically. Nine patients underwent MRI, which identified a collection in 88% of cases despite severe neutropaenia. In patients with a collection identified on MRI prior to surgery, 80% had a drainable collection confirmed intraoperatively. Post-operative complications included two cases of sepsis from a presumed perianal source and one death. A total of 82% of patients experienced symptom resolution after surgery compared to 88% of patients managed conservatively.

CONCLUSION

This study has demonstrated that MRI is a useful diagnostic tool in evaluating perianal sepsis in patients with haematological malignancy, even during periods of severe neutropenia. We found that both conservative and surgical management strategies lead to resolution of symptoms.

The contribution of preoperative MRI to the surgical management of anal fistulas

PURPOSE

Anal fistula is an abnormal tract or cavity between the anal canal and perianal skin. Surgical treatment of anal fistulas requires the identification of the course of the primary and secondary tracts and their relation with the sphincter musculature in order to appropriately manage them and drain any abscess. Physical examination alone is not as accurate as imaging modalities in detecting these features of the fistula, and recurrences are usually due to missed or inadequately managed infective components. Magnetic resonance imaging (MRI) is the preferred imaging modality for detecting anal fistulas, but which patient group should undergo preoperative MRI is a matter of debate. The aim of this study was to determine the contribution of MRI in the surgical management of anal fistulas.

METHODS

Medical records of patients who underwent surgery for primary anal fistula and preoperative MRI in our University Hospitals from January 1, 2008 to April 15, 2018 were collected anonymously and retrospectively. Any discrepancies between operative findings and MRI reports were noted. Two study groups were formed as per the contribution of preoperative MRI: significant and nonsignificant contribution groups. The significant contribution group included patients with secondary (blind) tracts, horseshoe fistulas, or abscesses undiagnosed at physical examination and examination under anesthesia; those with the location of the internal orifice different from that identified by physical examination; or those with the grade of the fistula assessed to be more advanced after preoperative MRI.

RESULTS

The total number of surgeries was 136. Mean patient age was 43±13 years. There were 106 males. In total, 47 patients suffered from recurrent fistulas. MRI contribution to clinical evaluation was significant in 33.8% of the patients. MRI more frequently provided significant information for complex fistulas than for simple fistulas. Significant preoperative MRI contribution was more frequent if the external opening was more than 2 cm away from the anal canal or when a horseshoe fistula was present.

CONCLUSION

Our study is valuable in linking physical examination findings with preoperative MRI findings. The distance of the external opening from the anal canal was not studied in the literature; our findings support the use of MRI for fistulas with external opening located more than 2 cm from the anus. These fistulas also tend to be complex and have a higher grade. In recurrent cases, MRI contributes not only by establishing the fistula anatomy but also by identifying possible sphincter damage.

The treatment of anal fistula: second ACPGBI Position Statement - 2018

It is over 10 years since the first ACPGBI Position Statement on the management of anal fistula was published in 2007. This second edition is the result of scrutiny of the literature published during this time; it updates the original Position Statement and reviews the published evidence surrounding treatments for anal fistula that have been developed since the original publication.

Diagnostic performance of intravoxel incoherent motion diffusion-weighted imaging and dynamic contrast-enhanced MRI for assessment of anal fistula activity

Objective

To evaluate intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) sequences for quantitative characterization of anal fistula activity.

Methods

This retrospective study was approved by the institutional review board. One hundred and two patients underwent MRI for clinical suspicion of anal fistula. Forty-three patients with demonstrable anal fistulas met the inclusion criteria. Quantitative analysis included measurement of DCE and IVIM parameters. The reference standard was clinical activity based on medical records. Statistical analyses included Bayesian analysis with Markov Chain Monte Carlo, multivariable logistic regression, and receiver operating characteristic analyses.

Results

Brevity of enhancement, defined as the time difference between the wash-in and wash-out, was longer in active than inactive fistulas (p = 0.02). Regression coefficients of multivariable logistic regression analysis revealed that brevity of enhancement increased and normalized perfusion area under curve decreased with presence of active fistulas (p = 0.03 and p = 0.04, respectively). By cross-validation, a logistic regression model that included quantitative perfusion parameters (DCE and IVIM) performed significantly better than IVIM only (p < 0.001). Area under the curves for distinguishing patients with active from those with inactive fistulas were 0.669 (95% confidence interval [CI]: 0.500, 0.838) for a model with IVIM only, 0.860 (95% CI: 0.742, 0.977) for a model with IVIM and brevity of enhancement, and 0.921 (95% CI: 0.846, 0.997) for a model with IVIM and all DCE parameters.

Conclusion

The inclusion of brevity of enhancement measured by DCE-MRI improved assessment of anal fistula activity over IVIM-DWI only.

Management of complex anorectal fistulas with seton drainage plus partial fistulotomy and subsequent ligation of intersphincteric fistula tract (LIFT)

BACKGROUND

Ligation of intersphincteric fistula tract (LIFT) is a relatively new technique in the treatment of complex anorectal fistulas. As it spares the anal sphincter, rates of post-operative incontinence may be lower when compared to conventional treatment. To date, there have not been enough reports of long-term fistula recurrence rates. We performed a long-term follow-up study of 75 patients who underwent LIFT following seton drainage and partial fistulotomy.

METHODS

Only patients with complex cryptogenic anorectal fistulas were included. After seton insertion and partial fistulotomy, the tract was reviewed at 4 months for the absence of anorectal sepsis. Patients then underwent LIFT in a day surgery setting. Operative time, complications, recurrences and incontinence were evaluated.

RESULTS

Between May 2008 and June 2013, 75 patients [51 men, mean age 49.5 years, standard error of the mean (SEM) 1.4 years] were treated with a LIFT protocol. The mean operating time for LIFT was 13.2 min (SEM 1.5 min). Complications included minor bleeding, superficial wound dehiscence and perianal pain. At a mean follow-up of 14.6 months (SEM 1.7 months), there were nine (12 %) recurrences, diagnosed at a mean 9.2 months (SEM 2.7 months). They were treated with seton insertion followed by LIFT with biomesh or anorectal advancement flap, and there were no subsequent recurrences. Review of preoperative and post-operative continence scores revealed only one (1.3 %) patient with minor incontinence following LIFT. Recurrences were significantly related to fistulas with multiple tracts (p < 0.001).

CONCLUSIONS

Our results suggest that the protocol of seton insertion and partial fistulotomy followed by LIFT is associated with a low recurrence rate comparing well with published results from studies involving other techniques and protocols for treating anal fistula.

Methods for preoperative assessment of anal fistula

Anal fistula is one of the most common perianal diseases, and methods for its preoperative assessment are diverse. Traditional methods include physical examination, probing, Goodsall's law, methylene blue test, and so on. Although traditional methods play a role, their accuracy for complex anal fistulas is low. Therefore, their application must be combined with other methods. Fistulography fails to depict the relationship of the fistula to the sphincter complex, and computed tomography lacks specificity to distinguish between fistula and surrounding muscle tissue. Both methods are rarely used now. Magnetic resonance imaging and three-dimensional anorectal endosonography have become routine preoperative examinations and play an important role for guiding precise surgery. However, they also have their own shortcomings. In this paper, we will summarize a variety of methods for preoperative assessment of anal fistula.

Anal fistula: Intraoperative difficulties and unexpected findings

Anal fistula surgery is a commonly performed procedure. The diverse anatomy of anal fistulae and their proximity to anal sphincters make accurate preoperative diagnosis essential to avoid recurrence and fecal incontinence. Despite the fact that proper preoperative diagnosis can be reached in the majority of patients by simple clinical examination, endoanal ultrasound or magnetic resonance imaging, on many occasions, unexpected findings can be encountered during surgery that can make the operation difficult and correct decision-making crucial. In this article we discuss the difficulties and unexpected findings that can be encountered during anal fistula surgery and how to overcome them.

Can ileal pouch anal anastomosis be used in Crohn's disease?

Restorative proctocolectomy with IPAA is now accepted as the standard of care in most patients with a diagnosis of mucosal ulcerative or IndC requiring surgery. In patients with Crohn's colitis needing intervention, proctocolectomy with end ileostomy or subtotal colectomy with ileorectal anastomosis is still the treatment of choice. In the authors' institution they consider performing an ileal pouch for a diagnosis of Crohn's colitis requiring rectal resection provided there is no existing or previous evidence of perianal or small bowel CD. They only perform this in a well-motivated patient who understands the potential sequelae, including an increased incidence of adverse effects and reduced functional outcome, if they develop CD of the pouch. A significant amount of time must be allocated to the patient and their family when counseling them with regards to the potential surgical options and outcomes associated with each. The development of CD of the pouch is associated with a considerable pouch failure rate requiring pouch excision or indefinite ileostomy formation. It does not always herald disaster, however, and a large percentage of patients can be salvaged using a combination of medical and surgical therapy. In this patient group the maintenance of intestinal continuity and avoidance of an ostomy is often the most important factor in their perception toward quality of life. The search for a serologic or genetic marker that will predict disease outcome in this select patient group and thereby direct surgical decision making should continue. It is recommended that in the presence of Crohn's colitis the decision to perform an ileal pouch should only be made in a tertiary center under the care of gastroenterologists, histopathologists, and colorectal surgeons with experience in the management of these complex cases.