Reliability of endosonography in evaluation of anal fistulae and abscesses

Postoperative three-dimensional endoanal ultrasound findings and relation to anal fistula plug failure

OBJECTIVES

To explore the utilization of three-dimensional (3D) endoanal ultrasound (EAUS) for the follow-up of the anal fistula plug (AFP), describe morphological findings in postoperative 3D EAUS, and evaluate if postoperative 3D EAUS combined with clinical symptoms can predict AFP failure.

MATERIALS AND METHODS

A retrospective analysis of 3D EAUS examinations performed during a single-centre study of prospectively included consecutive patients treated with the AFP between May 2006 and October 2009. Postoperative assessment by clinical examination and 3D EAUS was performed at 2 weeks, 3 months and 6-12 months ("late control"). Long-term follow-up was carried out in 2017. The 3D EAUS examinations were blinded and analysed by two observers using a protocol with defined relevant findings for different follow-up time points.

RESULTS

A total of 95 patients with a total of 151 AFP procedures were included. Long-term follow-up was completed in 90 (95%) patients. Inflammation at 3 months, gas in fistula and visible fistula at 3 months and at late control, were statistically significant 3D EAUS findings for AFP failure. The combination of gas in fistula and clinical finding of fluid discharge through the external fistula opening 3 months postoperatively was statistically significant (p < 0.001) for AFP failure with 91% sensitivity and 79% specificity. The positive predictive value was 91%, while the negative predictive value was 79%.

CONCLUSIONS

3D EAUS may be utilized for the follow-up of AFP treatment. Postoperative 3D EAUS at 3 months or later, especially if combined with clinical symptoms, can be used to predict long-term AFP failure.ClinicalTrials.gov identifier NCT03961984.

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.

Fistula in Ano

An accurate delineation of the surgical anatomy of perianal inflammatory disease is vital before surgery to prevent postoperative recurrence and incontinence. The purpose of this study was to evaluate the use of transperineal sonography for evaluating perianal inflammatory disease. Thirty patients (23 males and 7 females) with clinically suspected perianal inflammatory disease were imaged with transperineal sonography in males and transperineal and transvaginal sonography in females. All fluid collections, sinus tracts, and fistulae were evaluated in relation to the sphincters and perineum. Twenty-seven of the 30 patients had fistulae: 7 intersphincteric, 17 transphincteric, and 1 extrasphincteric fistula. Three patients had perianal fluid collections with sinus tracts. Preoperative sonographic findings were confirmed in 23 patients. Thirty-one internal openings seen on sonography were confirmed on surgery. The authors conclude that transperineal and transvaginal sonography are accurate and painless methods for documenting perianal inflammatory disease.

Incidence and clinical outcomes of intersphincteric abscesses diagnosed by anal ultrasonography in patients with crohn's disease

BACKGROUND

Intersphincteric abscesses have been reported as uncommon manifestations of perianal Crohn's disease (CD) in surgical series, and may be diagnosed earlier by means of anal ultrasonography. The aim of this study was to evaluate the incidence and outcomes of intersphincteric abscess in a prospective cohort of patients with CD referred for perianal symptoms.

METHODS

Of the 420 patients with CD attending our outpatient clinic over a period of 5 years, 55 (31 males, mean age 38 ± 13 years) underwent anal ultrasonography because of newly developed symptoms suggesting perianal disease; a clinical evaluation and perianal examination was performed on the same day.

RESULTS

An intersphincteric abscess was diagnosed in 23 (42%) of the 55 patients with perianal symptoms, for a total cumulative 5-year incidence of 5% (95% confidence interval [CI]: 3%-7%). During a median follow-up period of 23 months (range 6-53), four of these patients required surgery, four developed a perianal fistula or small ischiorectal abscess not requiring surgery, and 15 experienced a benign course. The patients with a benign course had a longer duration of CD at the time of onset of the perianal symptoms.

CONCLUSIONS

Intersphincteric abscesses frequently cause perianal symptoms in patients with CD, and their clinical outcomes vary from rapidly progressive inflammation to a benign self-limiting course. The favorable outcome observed in some patients supports a first-line conservative approach to the condition.

Ultrasonographic assessment of patients referred with chronic anal pain to a tertiary referral centre

BACKGROUND

Chronic anal pain is relatively common as a presentation to specialist physicians and surgeons. Currently, it is regarded as a functional disorder upon the exclusion of occult intersphincteric sepsis. Our study assessed an unselected cohort of patients presenting with chronic previously undiagnosed anal pain using routine ultrasonography.

METHODS

All patients referred to a tertiary gastroenterology service between January 2005 and January 2008 with a diagnosis of chronic anal pain (>3 months duration with no clinical anorectal signs) underwent endoanal and static and dynamic transperineal ultrasound to assess for the frequency and pattern of occult intersphincteric sepsis.

RESULTS

Of 1,580 patients referred, there were 146 presenting with chronic anal pain as a main symptom. Of these, 37 (25.3%) had intersphincteric sepsis (ISS) diagnosed with ultrasound examination with 17 undergoing evaluable surgery. There was a male preponderance (70.3%) with the diagnosis being made in 46% of cases after 6 months of symptoms and with 80.8% having posteriorly located sepsis. This occurred on a background of 62% having previous acute proctological conditions. There was complete ultrasonographic and operative concordance with 15 becoming asymptomatic after surgery at a mean follow-up of 6 months.

CONCLUSION

Occult intersphincteric sepsis is not uncommon and is diagnosed using routine ultrasonography at the time of clinical presentation. Endoanal and transperineal ultrasound is recommended as part of the investigative armamentarium to exclude categorization as functional anorectal pain. This is currently not part of the Rome III coding for such a diagnosis suggesting a revision of these diagnostic criteria for the ultimate diagnosis of functional proctalgia.

Imaging of perianal fistulas

Perianal fistulas, cryptoglandular or Crohn's disease-related, have a tendency to recur. Recurrence usually is owing to missed infection during surgery for cryptoglandular fistulas or insufficient response to medical treatment in Crohn's disease. It is now recognized that preoperative imaging (endoanal ultrasound and magnetic resonance imaging) can help to identify extensions that otherwise would be missed during surgery and therefore prevent recurrence. For medical therapy, the extent of the disease and the presence of abscesses are identified with imaging and therapy response can be monitored. The purpose of this review is to give an up-to-date overview of the anal anatomy, classification of perianal fistulas, and the role of imaging modalities in the management of patients with perianal fistulas.

Endoanal ultrasound in benign anorectal disorders: clinical relevance and possibilities

Endoanal ultrasound is a well-established technique used to evaluate benign anorectal disorders. The technique is easy to perform, has a short learning curve and causes very little discomfort. Reconstruction of 3D images is possible. The clinical indications for endoanal ultrasound in benign anorectal diseases are fecal incontinence and peri-anal fistula. Sphincter defects can be depicted with precision and correlate perfectly with surgical findings. Furthermore, an impression of sphincter atrophy can be established. With perianal fistula the tracts can be visualized. Introducing hydrogen peroxide via the external fistula opening improves imaging. Endoanal ultrasound and MRI have comparable results in diagnosing anorectal disorders.

Prognostic value of endoanal ultrasound for fistula-in-ano: a retrospective analysis

PURPOSE

This study was designed to assess whether preoperative endoanal ultrasound plays a prognostic role in the surgical outcome of anal fistula.

METHODS

A retrospective review was conducted at a single institution.

RESULTS

Sixty-nine patients underwent 83 studies. Indications for endoanal ultrasound included complex fistulas and tracts, multiple external openings, recurrent fistulas, and/or failed previous surgical intervention. Mean age was 51.7 years. Fifty-three patients (77 percent) were men. Mean duration of symptoms was 3.1 years. Forty-nine patients (71 percent) had undergone previous surgical intervention to eradicate sepsis or fistula. Sixty patients (87 percent) underwent surgical interventions and were divided into two groups: Group A (73.3 percent), concordance with ultrasound findings; and Group B (26.7 percent), nonconcordance. Mean follow-up in the surgical group was 15.6 months. Measured outcome was total number of operations per patient and failure rate of primary surgical intervention. No difference was noted in mean total number of operations between Group A (1.57) and Group B (1.69) (P = 0.71). There was a statistically nonsignificant trend toward a higher failure rate of the primary intervention in the nonconcordance group [failure rate 18.2 percent in Group A vs. 25 percent in Group B (P = 0.72)].

CONCLUSIONS

The findings and accuracy of preoperative endoanal ultrasound did not influence postoperative outcome.

The role of transperineal ultrasonography in the assessment of the internal opening of cryptogenic anal fistula

PURPOSE

The aim of this study was to assess the reliability of transperineal ultrasonography (TPUS) in the pre-operative identification of the internal opening of anal fistulas compared to conventional proctological examination and operative findings.

METHODS

Forty-three patients with anal fistula were assessed by TPUS with and without the use of hydrogen-peroxide injection (E-TPUS) in an attempt to identify the internal opening. Results were compared to preoperative conventional examination and operative findings.

RESULTS

Operative assessment showed an anterior internal opening in 29 patients (67.4%) and a posterior opening in 14 (32.6%). Compared to the operative findings, the agreement rate for the identification of the internal opening was 74.4% for physical examination alone, 93.0% for TPUS and 90.7% for E-TPUS. Physical examination was less accurate in detecting the internal opening than both TPUS (p=0.014) and E-TPUS (p=0.026).

CONCLUSIONS

TPUS and E-TPUS are superior to physical examination in the identification of internal openings in anal fistulas. Hydrogen peroxide injection does not provide additional advantages.

Endosonography in anorectal disease: an overview

Anorectal endosonography (AE), which was introduced 20 years ago, derives from the study of urology. It was first used to evaluate rectal tumours and later also to investigate benign disorders of the anal sphincters and pelvic floor. The technique is easy to perform, it has a short learning curve and causes no more discomfort than a routine digital examination. A rotating probe with a 360 degrees radius and a frequency between 5 and 16 MHz is introduced to the rectum and then slowly withdrawn so that the pelvic floor and subsequently the sphincter complex are seen. Recently, it has become possible to reconstruct three-dimensional images. AE has been used for almost every possible disorder in the anal region and has increased our insight into anal pathology. The clinical indications for AE are: 1. Faecal incontinence in patients when surgery is an option. AE can show sphincter defects with excellent precision. There is a perfect correlation with surgical findings. Studies comparing AE with endoanal magnetic resonance imaging (MRI) have shown that both methods are equally good for demonstrating defects in the external anal sphincter; the internal anal sphincter is better visualized with AE. After sphincter repair, the effect is directly related to the decrease in the sphincter defect. 2. Perianal fistulae. AE has been shown to be accurate in staging perianal cryptoglandular fistulae and fistulae in Crohn's disease. When there is an external fistula opening, H2O2 can be introduced with a plastic infusion catheter. The tract then becomes visible as a hyperechoic lesion ("white"). It has been shown that this corresponds well with surgical findings. It is equally sensitive as endoanal MRI. Since recurrent cryptoglandular fistulae are complex in 50% and Crohn's fistula in 75%, it is mandatory to perform AE preoperatively in these patients to avoid missed tracts during surgery and subsequent recurrences. 3. Rectal tumors. In low tubulovillous adenomas or malignant polyps considered removable locally, confirming the local resectability (T0 or T1) is mandatory. Although larger rectal and more advanced tumours can be evaluated with AE, MRI is more sensitive in staging nodal involvement. 4. Anal carcinoma for staging. AE has been shown to stage better than the classical TNM classification for both local extension and prognosis. In conclusion, AE images the internal and external anal sphincter with high accuracy. It is easy to perform and is of particular value in the diagnosis of anal incontinence and perianal fistulae. It is excellent in staging anal carcinoma and can also be used in staging rectal carcinoma, especially very low large malignant polyps.

Endoanal magnetic resonance imaging of fistula-in-ano: a comparison of STIR with gadolinium-enhanced techniques

PURPOSE

To compare a STIR sequence with gadolinium-enhanced techniques on endoanal magnetic resonance (MR) imaging of fistulas-in-ano by correlating the findings with those at surgery.

MATERIAL AND METHODS

Twenty-two consecutive patients with clinical suspicion of perianal sepsis were studied using an endoanal coil followed immediately by a phased array coil. T1-weighted precontrast and postcontrast and STIR images in transverse and coronal planes were produced with each coil and analysed by noting the presence and site of a collection, primary track, the position of any internal opening, and subcutaneous or supralevator extension. An "expert" and also a "trainee" radiologist assessed the images. Operative findings were similarly recorded. The Fisher exact test was used to compare imaging with surgery. Interobserver variation was calculated using a kappa statistic.

RESULTS

Of 22 patients with suspected fistulas, 8 were simple, 4 were complex, and 3 were superficial sinuses. Five had no anal pathology, 1 had anal excoriation, and 1 had a polyp. At surgery, 6 intersphincteric, 1 transsphincteric, 8 extrasphincteric, no supralevator collections, and 9 internal openings were noted. The overall sensitivity and specificity for detecting these were 75% and 64%, respectively, for STIR imaging, and 58.3% and 62.8% for gadolinium-enhanced imaging. There was good agreement between the "trainee" and the "expert" in the interpretation of images (kappa=0.7).

CONCLUSION

A STIR sequence is more sensitive overall than gadolinium-enhanced techniques on endoanal magnetic resonance imaging of fistulas-in-ano because of increased sensitivity in detecting the internal opening. A combination of endoanal and phased array techniques using STIR imaging sequences is valuable preoperative assessment in both simple and complex cases.

Hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging in evaluating perianal fistulas: agreement and patient preference

OBJECTIVES

To determine agreement between hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography (3D HPUS) and endoanal magnetic resonance imaging (MRI) in preoperative assessment of perianal fistulas, and to assess patient preference with regard to these techniques.

METHODS

Forty patients (31 males, aged 21-70 years) with symptoms of a perianal fistula and a visible external opening underwent preoperative 3D HPUS and endoanal MRI. The results were assessed separately by experienced observers. Fistulas were described according to the following characteristics: classification of the primary fistula tract according to Parks, location of the internal opening, presence of secondary tracts and fluid collections. Patients were asked to score the amount of discomfort experienced during both procedures and express their preference for either method.

RESULTS

The median time interval between 3D HPUS and endoanal MRI was 14 days (range, 0-91 days). The methods agreed in 88% (35/40, kappa = 0.45) for the primary fistula tract, in 90% (36/40, kappa = 0.83) for the location of the internal opening, in 78% (31/40, kappa = 0.62) for secondary tracts, and in 88% (35/40, kappa = 0.63) for fluid collections. Both methods were associated with similar discomfort, and there was no patient preference for one procedure over the other.

CONCLUSIONS

3D HPUS and endoanal MRI are equally adequate for the evaluation of perianal fistulas. Both methods are associated with similar discomfort and patients have no preference for either procedure.