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Int J Colorectal Dis DOI 10.1007/s00384-015-2167-0

ORIGINAL ARTICLE

Role of tridimensional endoanal ultrasound (3D-EAUS) in the preoperative assessment of perianal sepsis Antonio Brillantino & Francesca Iacobellis & Giandomenico Di Sarno & Francesco D’Aniello & Domenico Izzo & Fiorella Paladino & Maurizio De Palma & Maurizio Castriconi & Roberto Grassi & Natale Di Martino & Adolfo Renzi

Accepted: 10 February 2015 # Springer-Verlag Berlin Heidelberg 2015

Abstract Purpose The aim of this study was to evaluate the accuracy of tridimensional endoanal ultrasound (3D-EAUS) in the diagnosis of perianal sepsis comparing the results with the surgical findings, considered as reference standard. Methods From January 2009 to January 2013, all the patients referred for the assessment and treatment of perianal sepsis with suspected anorectal origin were enrolled in the study. All patients gave informed written consent. Prior to surgery, all the patients underwent anamnestic evaluation, clinical examination, and unenhanced and H2O2-enhanced 3D-EAUS. Surgery was performed by a colorectal surgeon blinded to the 3D-EAUS results.

Antonio Brillantino and Francesca Iacobellis contributed equally to this work. A. Brillantino : F. Paladino Emergency Department “A. Cardarelli” Hospital, Via A. Cardarelli 9, 80131 Naples, Italy A. Brillantino : G. Di Sarno : F. D’Aniello : A. Renzi “Villa delle Querce” Hospital, Via Battistello Caracciolo 48, 80136 Naples, Italy F. Iacobellis (*) : R. Grassi Department of Radiology, Second University of Naples, Piazza Miraglia 2, 80138 Naples, Italy e-mail: [email protected] D. Izzo “Mediterranea” Hospital, Via Orazio, 2, 80122 Naples, Italy M. De Palma : M. Castriconi Department of Surgery, “A. Cardarelli” Hospital, Via A. Cardarelli 9, 80131 Naples, Italy N. Di Martino VIII Department of General and Gastrointestinal Surgery, Second University of Naples, Piazza Miraglia 2, 80138 Naples, Italy

Results A total of 212 patients with suspected perianal suppurations were assessed during the study period. In 12 patients, the H2O2-enhanced 3D-EAUS was not performed, and so, they were excluded from the study. Very good agreement between 3DEAUS and examination under anesthesia (EUA) in the classification of primary fistula tracts (kappa=0.93) and in the identification of fistula internal opening (kappa=0.97) was found. There was a good concordance (kappa=0.71) between 3D-EAUS and surgery in the detection of fistula secondary extensions. The overall sensitivity and specificity of 3D-EAUS in the diagnosis of perianal sepsis were 98.3 and 91.3 % respectively. Conclusion 3D-EAUS is a safe and reliable technique in the assessment of perianal sepsis. It may assist the surgeon in delineating the fistula tract anatomy and in determining the origin of sepsis, supporting the preoperative planning of definitive and appropriate surgical therapy. Keywords Tridimensional endoanal ultrasound . 3D-EAUS . Perianal sepsis . Perianal abscess . Perianal fistula . Fistula tract . Criptoglandular infection

Introduction Since the introduction in the clinical practice, endoanal ultrasound (EAUS) has been used to assess patients with anal incontinence, pain, malignancy, and sepsis, as well as to evaluate the completeness of sphincter repair following surgery [1–6]. Particularly, an accurate preoperative assessment of perianal sepsis is crucial for planning the most effective surgical procedure, reducing the risk of postoperative recurrence and improving the clinical outcome [7]. In this context, the advent of high-resolution three-dimensional technology has rekindled interest in the endoanal

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ultrasound [8], improving the accuracy in the visualization of fistula tracks, identification of internal openings, and evaluation of secondary extensions [9, 10]. However, the role and accuracy of tridimensional endoanal ultrasound (3D-EAUS) in the management and diagnosis of all types of perianal suppurations is still not widely elucidated. The aim of this study was to evaluate the accuracy of 3DEAUS in the diagnosis of perianal sepsis comparing the results with the surgical findings, considered as reference standard.

Patients and methods From January 2009 to January 2013, all the patients referred for the assessment and treatment of perianal sepsis with suspected anorectal origin were inserted in a prospective database, including the results of clinical evaluation, instrumental studies, and any subsequent examination under anesthesia and surgical treatment. The local ethical committee approved the study protocol. All patients gave informed written consent. Prior to surgery, all the patients underwent anamnestic evaluation, clinical examination, and 3D-EAUS. Clinical examination and ultrasound were performed, respectively, by a colorectal surgeon and a radiologist together with the same surgeon. Surgery was performed by another colorectal surgeon blinded to 3D-EAUS results.

transducer head was shifted in proximal-distal direction up to obtain the three-dimensional images of the distal rectum and the anus, displayed as a cube. Perianal fistulas and abscess were visualized, respectively, as hypoecoic tracks or masses occasionally containing focal hyperechoic areas representing gas, whereas the internal openings were identified and categorized according to previous described endosonographic criteria [11]. The examined fistula characteristics were the primary track (classified according to Parks’s criteria [12]), the internal openings (anterior, right lateral, posterior, left lateral), and the secondary extensions, including horseshoe tracks. After the pre-enhanced images were saved, H2O2-enhanced sonography was performed. Briefly, ultrasonographic scan was performed about 15 s after injection of 3 mL of H2O2 3 % through the suspected external openings, using a flexible intravenous cannula. Due to formation of small air bubbles, the internal openings and fistula tracks were visualized, respectively, as hyperechoic breaches and tracks. The abscesses and fistulas were considered of not criptoglandular origin if no morphologic relationship with anorectal musculature and subepithelial tissue was found at unenhanced and H2O2-enhanced 3D-EAUS. Examination under anesthesia (EUA)

After obtaining the anamnesis, inspection and palpation of perianal area followed by anorectal digital examination were performed with patients in left lateral decubitus position. Fistula probes were not used to avoid the creation of additional tracks. The number and the sites of suspected external openings, the swellings of perineal area, and tenderness, masses or indurations at anorectal digital examination were examined and registered. After physical examination, ano-recto-sigmoidoscopy was also performed to rule out any malignancy.

All patients received a 200-mL enema a few hours before the procedure. Atropine (1 mg) and midazolam (5 mg; Ipnovel, Roche, Milan, Italy) were intravenously administered. Cefotaxime (1 g) was intravenously administered as antibiotic prophylaxis. The surgical procedures were performed under subarachnoid anesthesia with patients in the lithotomy position. In the presence of suspected external orifices, Lockart Mummary fistula probes and H2O2 were used to search for the fistula tracks and identify the internal openings. All the abscesses were incised and evacuated. The site and number of external openings, the site of internal openings, and the anatomic relationship between fistulas or abscesses and anorectal musculature were examined and recorded.

Ultrasound

Statistical analysis

The B-K Medical 2050 anorectal transducer (B-K Medical, Herlev, Denmark) with a 360° rotating head and a work frequency ranging between 6 and 16.0 MHz was used for morphologic evaluation of fistulas, abscess and anal sphincters. Patients were evaluated in the left-lateral position without any sedation. The lubricated probe was inserted through the anus in the lower rectum for about 6 cm, and then, without moving the probe’s position, pushing a specific button on the probe, the

Statistical analysis was carried out using the program SPSS (SPS Inc., Chicago, IL) and InStat GraphPad Prism® five (San Diego, California, USA). Values are expressed as means±standard deviation (SD) or medians and range. Continuous data were compared between each group using the Student’s t test or the Mann–Whitney U test, when indicated. Prevalence data were compared between groups using the two-sided χ2 test or Fisher’s exact test, when indicated.

Clinical examination

Int J Colorectal Dis

The concordance between 3D-EAUS and EUA was assessed using the simple kappa coefficient (k). A probability value of less than 0.05 was considered significant.

Results Clinical examination A total of 212 patients (91 females, 121 males, mean age 45± 12.4) with suspected perianal suppurations were assessed during the study period. Of these, 24 (11.3 %) had recurrent fistulas after surgery, 169 (79.7 %) presented a first fistula, and 16 (7.6 %) showed a perianal abscess. Perianal pus/blood discharge, swelling, and pain were the main preoperative symptoms, being reported, respectively, in 81 % (172/212), 47.6 % (101/212), and 57 % (121/212) of cases. Three patients (1.4 %) complained of acute anal pain and fever without showing external signs of suppuration or anal fissure at anorectal examination. Out of these, 1 (33.3 %) patient showed a fluctuant mass at anorectal digital exploration. Of 193 patients with suspected first or recurrent fistulas, 174 (90.1 %) showed only one suspected external orifice whereas 19 (9.8 %) showed two or more suspected external openings. At anamnestic evaluation, eight patients (3.7 %) presented Crohn’s disease, two (0.9 %) reported previous anorectal trauma, and one (0.4 %) underwent surgery for rectal cancer. No remarkable previous diseases were reported by the other 201 (94.8 %) patients. Table 1

Tridimensional endoanal ultrasound (3D-EAUS) The 3D-EAUS was conducted in all the 212 enrolled patients. No severe local pain after the probe introduction was registered. In 5.6 % of patients (12/212), the H2O2-enhanced 3D-EAUS was not performed because of pain during the external orifice cannulation. Although these patients underwent unhenanced 3D-EAUS, they were excluded from the study. Two hundred patients underwent both unenhanced and H2O2-enhanced 3D-EAUS and constituted the object of the analysis. At 3D-EAUS, an anorectal origin of sepsis was excluded in 11 % (22/200) of cases and confirmed in 89 % (178/200) of patients. Out of these, 19 (19/178=10.7 %) showed a perianal abscess and 159 (159/178=89.3 %) presented perianal fistulas. Among these last, 149 (149/159=93.7 %) showed a single perianal fistula and 10 (10/159=6.3 %) presented, at same time, two perianal fistulas. The perianal abscesses and fistulas were considered of criptoglandular origin in 93.8 % (167/178) of patients whereas in 6.2 % (8/178), 1.1 % (2/178), and 0.5 % (1/178) of cases, they were associated with Crohn’s disease, anorectal trauma, and rectal cancer, respectively. The endosonographic results are summarized in Table 1. –

Abscesses The 19 perianal abscesses were classified as superficial, intersphincteric, or infraelevator, in 15.8 % (3/19), 42.1 % (8/19), and 42.1 % (8/19) of cases, respectively. Of the patients with intersphincteric abscesses, 37.5 % (3/8) complained for acute anal pain without

3D-EAUS findings 3D-EAUS

NO ARO 11 % (22/200 pts) ARO 89 % (178/200 pts)

Abscesses 10.7 % (19/178) pts

Fistulas 89.3 % (159/178) pts

Superficial Intersphincteric Supraelevator

15.8 % (3/19) 42.1 % (8/19) 0

Infraelevator Primary tracts no. 169

42.1 % (8/19) Superficial Intersphincteric Transphincteric Suprasphincteric Extrasphincteric

Internal openings Secondary tracts Horseshoe tracts 3D-EAUS tridimensional endoanal ultrasound, EUA examination under anesthesia, ARO anorectal origin, pts patients

3 % (5/169) 27.8 % (45/169) 64.5 % (109/169) 3.5 % (6/169) 1.2 % (2/169) 98.2 % (166/169) 21.8 % (37/169) 3.5 % (6/169)

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signs of anal fissure and/or suppuration at physical examination. Fistula primary tracts At 3D-EAUS, 169 fistula primary tracts in 159 patients with perianal fistulas were identified and classified, according with Park’s classification, as superficial in 3 % (5/169) (Fig. 1), intersphincteric in 27.8 % (47/169) (Fig. 2a, b), transphincteric in 64.5 % (109/169) (Fig. 3), suprasphincteric in 3.5 % (6/169) (Fig. 4), and extrasphincteric in the 1.2 % (2/169) of cases. Fistula internal openings At 3D-EAUS, 166 internal openings were identified in 159 patients with perianal fistulas. Particularly, 3 (3/159=1.8 %) patients showed two primary tracts with a single internal opening, 7 (7/159 = 4.4 %) presented two primary tracts with different internal openings, and 149 (149/159 = 93.7 %) showed a single perianal fistula. Fistula secondary tracts One or more secondary extensions were identified in 21.8 % (37/169) of cases. Horseshoe tracts were identified in 3.5 % of perianal fistulas (6/169).

EUA in comparison with 3D-EAUS Basing on the intraoperative findings, an anorectal origin of sepsis was confirmed in 89.5 % (179/200) and excluded in 10.5 % (21/200) of patients. In these last, the intraoperative diagnosis was sinus pilonidalis in 52.4 % (11/21), hidradenitis suppurativa in 19 %

Fig. 1 Unenhanced 3D-EAUS image of a superficial anterior fistula

(4/21), Bartholin’s cyst in 9.5 % (2/21), furunculosis in 14.3 % (3/21), and Fournier’s syndrome in 4.8 % (1/21) of cases. Two sinus pilonidalis were classified as perianal fistulas at 3D-EAUS. Among the patients with sepsis of anorectal etiology, 20 (20/179=11.1 %) showed a perianal abscess and 159 (159/ 179=88.8 %) presented perianal fistulas. The overall sensitivity and specificity of 3D-EAUS in the diagnosis of sepsis with anorectal source were 98.3 and 91.3 % respectively. The EUA results are summarized in Table 2. –



Abscesses Twenty perianal abscesses were identified and classified as superficial, intersphincteric, supraelevator, and infraelevator in 15 % (3/20), 40 % (8/20), 5 % (1/20), and 40 % (8/20) of cases, respectively. At 3D-EAUS, one supraelevator abscess was undiagnosed and the 19 abscesses were correctly classified. Fistula primary tracts During surgery, 171 primary fistula tracts were identified and classified as superficial in 4.1 % (7/171), intersphincteric in 28.7 % (49/171), transphincteric in 60.8 % (104/171), suprasphincteric in 5.3 % (9/171), and extransphincteric in 1.2 % (2/171) of cases. Superficial fistulas were correctly identified at 3DEAUS in 71.4 % (5/7) and undetected in 28.6 % (2/7) of cases. Intersphicteric fistulas were rightly identified in 95.9 % (47/49) and misinterpreted as transphincteric fistulas in 4.1 % (2/49) of cases, by 3D-EAUS.

Fig. 2 Unenhanced 3D-EAUS image of an intersphincteric fistula

Int J Colorectal Dis Fig. 3 Unenhanced (a) and enhanced (b) 3D-EAUS images of a transphincteric posterior fistula



Suprasphincteric fistulas were exactly diagnosed at 3D-EAUS in 66.6 % (6/9) and misdiagnosed as transphincteric fistulas in 33.4 % (3/9) of cases. Extrasphincteric fistulas were correctly identified at 3D-EAUS in 100 % (2/2) of cases. All the surgically detected transphincteric fistulas were correctly identified and classified with 3D-EAUS. In summary, five fistulas (three suprasphincteric and two intersphincteric) were incorrectly classified as transphincteric fistulas, and two perianal superficial fistulas were undiagnosed at 3D-EAUS. Very good agreement (kappa =0.93) between 3DEAUS and EUA in the classification of primary fistula tracts was found. Fistula internal openings During surgery, 166 internal openings were identified in 159 patients with perianal fistulas. In two cases, the



internal openings detected by 3D-EAUS were not found at surgery and an intraoperative diagnosis of sinus pilonidalis was made. These three patients showed recurrent disease after surgery at 3 months follow-up. Very good agreement (kappa =0.97) between 3DEAUS and EUA in the identification of fistula internal opening was found. Fistula secondary tracts One or more secondary extensions were found in 23.8 % (41/171) of cases, and horseshoe tracts were identified in 3.5 % of perianal fistulas (6/171). There was a good concordance (kappa = 0.71) between 3D-EAUS and surgery in the detection of fistula secondary extensions

Discussion

Fig. 4 Enhanced 3D-EAUS image of an anterior suprasphincteric fistula

Perianal sepsis represents a common benign anal condition with multiple etiopathogenesis and variable treatment options [13–15]. The treatment strategy strictly depends on the origin of sepsis (criptoglandular or not) and on the anatomy and extension of the fistula tracts. Although anorectal abscess and fistula-in-ano are commonly diagnosed and managed by colorectal surgeons on the basis of clinical findings alone, adjunctive radiological studies can provide further and valuable pieces of information about the sepsis extension and anatomy. Particularly, previous studies suggested that 3D-EAUS, providing an accurate anatomic assessment of fistula-in-ano, is useful in the preoperative planning of definitive and appropriate surgical therapy, decreasing the risk of anal incontinence and recurrence [16–24]. However, the perianal sepsis may arise not only from criptoglandular infection but also from dermatological, gynecological, infectivological, and oncological

Int J Colorectal Dis Table 2

EUA findings EUA

NO ARO 10.5 % (21/200) pts

ARO 89.5 % (179/200) pts

Sinus pilonidalis Hidradenitis suppurativa Bartholin’s cyst Furunculosis Fournier’s syndrome Abscesses 11.2 % (20/179) pts

Fistulas 88.8 % (159/179) pts

Primary tracts no. 171

Internal openings Secondary tracts Horseshoe tracts

Superficial Intersphincteric Supraelevator Infraelevator Superficial Intersphincteric Transphincteric Suprasphincteric Extrasphincteric

52.4 % (11/21) 19 % (4/21) 9.5 % (2/21) 14.3 % (3/21) 4.8 % (1/21) 15 % (3/20) 40 % (8/20) 5 % (1/20) 40 % (8/20) 4.1 % (7/171) 28.7 % (49/171) 60.8 % (104/171) 5.3 % (9/171) 1.2 % (2/171) 98.2 % (166/171) 23.8 % (41/171) 3.5 % (6/171)

EUA examination under anesthesia, ARO anorectal origin, pts patients

conditions that may simulate an abscess or fistula of criptoglandular origin, challenging the preoperative differential diagnosis. The aim of this study was to evaluate the role of 3D-EAUS in the management of perianal sepsis. The 3D-EAUS appeared to be a simple, safe, and welltolerated procedure: No adverse events related to transanal probe introduction or H2O2 perianal injection were registered, and the cannulation of external orifices was possible and tolerated in the majority of patients. Basing on our results, the 3D-EAUS was a useful tool to evaluate the origin of sepsis. In our series, the 3D-EAUS detected an anorectal origin of perianal sepsis in 89 % of patients, and in only two cases, the internal openings detected by 3D-EAUS were not confirmed at surgery. However, these last two patients showed recurrent disease at 3 months follow-up, suggesting an inadequate intraoperative evaluation. In two patients with acute anal pain and fever and without external sings of perianal fissures and suppurations, 3DEAUS detected an intersphincteric abscess, missed to preoperative physical examination. These findings emphasize the role of 3D-EAUS in the differential diagnosis of perianal sepsis and seem to encourage the routine use of 3D-EAUS in the preoperative evaluation of perianal fistulas. In addition, the 3D-EAUS showed high accuracy in the definition of primitive perianal fistula morphology.

Indeed, good agreement between 3D-EAUS and surgery was found in the detection of internal openings, primary tracts, and secondary tracts. However, at 3D-EAUS, one pelvirectal abscess was not detected and five fistulas (three suprasphincteric and two intersphincteric) were classified incorrectly as transphincteric fistulas. These findings suggest that 3D-EAUS evaluation could overestimate the external sphincter involvement of the intersphincteric fistula tracts and underestimate the suprasphincteric extension of the transphincteric fistula tracts. According to other authors, this may be related with the structure alterations of anal canal and perianal muscles and tissues (which can overstage the fistula) and with the poor definition of the fistula tract when filled by inflammatory tissue (which can downstage the fistula) [25]. In our opinion, other factors may condition an accurate ultrasonographic definition of fistula anatomy. The normal configuration of puborectalis muscle, which appears as a ventrally open U-shaped ring, may influence the evaluation of the anatomical relationships between the sphincteric complex and the high anterior fistulas. For this reason, the anterior fistula tracts going through the puborectalis muscle level can be hardly defined with ultrasonography. Moreover, the lacking contact between endoprobe and lower rectal wall may lead to a poor definition of the fistula tracts extending over the puborectalis level and of the pelvirectal abscesses.

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Concerning this, during endosonographic evaluation of the high transphincteric fistulas and suspected suprasphinteric fistulas or abscesses, the routine use of the dedicated water-filled balloon into the lower rectum should be encouraged. In these cases, pelvic magnetic resonance imaging may represent a precious, valuable, and additional tool to accurately define the abscesses and fistula anatomy and their possible suprasphincteric extension such as in the presence of complex fistulas, recurrent fistulas, and Crohn’s disease [26–34].

Conclusion In view of these results, 3D-EAUS is a safe and reliable technique in the assessment of perianal sepsis. It may assist the surgeon in delineating the fistula tract anatomy and in determining the origin of sepsis, supporting the preoperative planning of definitive and appropriate surgical therapy. Other prospective studies are needed to assess whether concordance of preoperative EAUS imaging with intraoperative findings may impact the surgical outcome.

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