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Transperineal and Transvaginal Sonography of Perianal Inflammatory Disease

¹ All authors: Department of Medical Imaging, Toronto General Hospital-University Health Network, 200 Elizabeth St., Toronto, Ontario, Canada M5G 2C4.

Received January 23, 2001; accepted after revision March 8, 2001.

 
Address correspondence to S. R. Wilson.

Abstract

Top Abstract Introduction Subjects and Methods Results Discussion References

 
OBJECTIVE. Perianal infection arises in small intersphincteric anal glands predominantly located at the dentate line. Documentation of fluid collections and the relationship of inflammatory tracts to the sphincter mechanism is important for surgical treatment. Transanal sonography for assessment of perianal inflammatory disease is limited because placement of the rigid probe into the anal canal does not allow assessment of disease in the perineal region. The purpose of this study was to validate the use of transperineal sonography in men and both transvaginal and transperineal sonography in women for evaluation of perianal inflammatory disease.

SUBJECTS AND METHODS. Fifty-four patients, 28 men and 26 women, were imaged with transperineal and a combination of transperineal and transvaginal sonography, respectively. All patients were examined in the supine lithotomy and left lateral position with a transvaginal 8-to 4-MHz probe or a linear 12- to 7-MHz transducer. All fluid collections, sinus tracts, and fistulas were described by their location in relation to the sphincter mechanism and perineum.

RESULTS. Forty-six of 54 patients had perianal fistulas or sinus tracts: 33 transphincteric, seven intersphincteric, and six extrasphincteric. Fifteen patients had an associated abscess. In the eight remaining patients, there were two anovaginal fistulas, one rectovaginal fistula, one prolapsed internal hemorrhoid, two perianal complex masses, and two vascular perianal or perirectal inflammatory masses. Twenty-six patients underwent surgical procedures involving the anorectal canal or perirectal region, and of these, preoperative sonographic findings were confirmed in 22 (85%) of 26 patients. Three patients refused surgery, and six are awaiting surgery at this writing. Fifteen patients were treated conservatively.

CONCLUSION. Transperineal and transvaginal sonography are accurate, painless, and cost-effective methods for documenting perianal fluid collections and fistulas or sinus tracts or both.

Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Perianal abscess and fistula in ano are thought to arise from infection in small intersphincteric anal glands with abscess representing the acute manifestation and fistula in ano, a chronic condition. Fistulous abscess is the descriptive term given to both of these entities [1]. Perianal inflammatory disease is particularly common in Crohn's disease, with as many as one third of all patients presenting with perianal fissures, fistulas, or perianal abscesses at some stage [2]. In patients who do not have Crohn's disease, perianal inflammatory disease is still largely cryptoglandular in origin, likely caused by obstruction of intersphincteric anal glands either as a result of fecal material, foreign bodies, or trauma, with subsequent stasis and infection. Infection may spread caudally to the skin at the anal margin, cranially into the rectal wall, or laterally through the external anal sphincter into the ischioanal space [1].

Parks et al. [3] provided the currently used classification of fistula in ano. This classification system provides an anatomic description of fistulous tracts, which acts as a guide to operative treatment. According to this classification system, there are four main subtypes: intersphincteric (between the internal and external sphincter) (Fig. 1A), transphincteric (crossing both the internal and external anal sphincter into the ischiorectal or ischioanal fossa) (Fig. 1B), suprasphincteric (a tract passing upward in the intersphincteric plane to a point above the puborectalis muscle where it tracks laterally and caudally into the ischioanal fossa), and extrasphincteric (a tract passing directly from the perineal skin to the rectum outside both sphincters) (Fig. 1C).

View larger version (36K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A. —Selected schematic diagrams based on classification system by Parks et al. [3] illustrating most commonly encountered fistulas in our study population. (Reprinted with permission from [1]) Illustration of intersphincteric fistula shows infection spreading from intersphincteric anal glands caudally to skin at anal margin.

View larger version (29K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B. —Selected schematic diagrams based on classification system by Parks et al. [3] illustrating most commonly encountered fistulas in our study population. (Reprinted with permission from [1]) Illustration of uncomplicated transphincteric fistula shows that in this type of fistula, infection arising in intersphincteric anal glands spreads laterally through both internal and external anal sphincters into ischioanal fossa.

View larger version (35K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1C. —Selected schematic diagrams based on classification system by Parks et al. [3] illustrating most commonly encountered fistulas in our study population. (Reprinted with permission from [1]) Illustration of complicated extrasphincteric fistula shows that in this type of fistula, infection of intersphincteric anal glands crosses both sphincters and spreads caudally to perineum and cranially to point above levator ani muscle at which it opens secondarily into rectum.

Transanal sonography is useful in the investigation of fecal incontinence [4, 5], anorectal neoplasia [6], and complex perirectal infection [7]. Imaging of perianal inflammatory disease is, however, limited with this technique because placement of the rigid probe into the anal canal does not allow assessment of disease in the perineal region. MR imaging has been shown to be useful in the evaluation of perianal fistula [8] and in the assessment of the perineal complications of Crohn's disease [9]. However, this modality lacks real-time capability and is time-consuming and costly.

Transperineal sonography has been shown useful for imaging the incompetent cervix in pregnant patients [10]. More recently, Rubens et al. [11] have described it as a potentially effective technique for assessment of the anal sphincter in fecal incontinence, for anal tumor evaluation, and for the evaluation of perianal inflammatory disease, although it is not widely used for any of these three indications.

At our institution, we have confirmed that transvaginal sonography is an accurate method for evaluation of the anal sphincter [5]. In female patients with perianal disease, we discovered the relative ease with which the transvaginal technique could be modified to include a transperineal approach to document the course of fistulous and sinus tracts. Currently, we use transperineal sonography in male patients and a combination of transvaginal and transperineal sonography in female patents to evaluate perianal inflammatory disease. In both sexes, we frequently choose the transvaginal probe for the transperineal scan because its small footprint and high resolution are excellent for superficial abnormalities. Because the documentation of all fluid collections and the relationship of fistulous and sinus tracts to the internal and external sphincter is crucial in planning appropriate treatment, we designed a study to validate the use of transperineal sonography and transvaginal sonography for the evaluation of perianal inflammatory disease.

Subjects and Methods

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Our study population comprised 54 consecutive patients (28 men and 26 women) with clinically suspected perianal inflammatory disease. Patients were 23-69 years old. Twenty-eight patients had Crohn's disease, and three had ulcerative colitis. Specific indications for the scans included suspected perianal abscess (n = 32), suspected fistula in ano (n = 12), suspected rectovaginal fistula (n = 4), proctalgia (n = 2), and one patient each with a tender rectal mass, a tender perineal mass, and a tender rectovaginal septal mass. One patient was referred for examination of cordlike thickening in the perineum.

All patients had routine pelvic sonography to assess any high pelvic abscess beyond the range of the transperineal probe. Transperineal scans were then obtained in the supine lithotomy and left lateral positions with either a linear 12- to 7-MHz transducer or a transvaginal 8- to 4-MHz probe (ATL 3000 or 5000; ATL Ultrasound, Bothell, WA). The probe was covered with a sterile glove or condom filled with transducer gel. Axial images of the anal canal were initially obtained for orientation in all patients. The probe was placed on the perineum anterior to the anal canal in male patients. Pressure was applied to the perineal body, and the probe was angled posteriorly and cephalad to image the anal canal and perianal region. A rocking motion of the probe from the site of optimal visualization was performed to allow visualization of the full length of the anal canal. In female patients, the transvaginal probe was placed low in the vagina and angled posteriorly to image the anal canal as described by Stewart and Wilson [5]. A transperineal scan was added if an inflammatory process extended beyond the field of view allowed by the transvaginal probe. The transducer was placed over any external opening in all patients, and oblique images were obtained as necessary to show any collections and to follow the course of fistulous and sinus tracts in relation to the sphincter mechanism. The external sphincter was visualized as a layer of mixed echogenicity outside a continuous circular hypoechoic band, representing the internal anal sphincter (Figs. 2A,2B and 3A,3B).

View larger version (126K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A. —35-year-old woman with normal anal canal who was referred for investigation of proctalgia. Transvaginal axial sonogram shows mid anal canal at level at which intersphincteric glands are most densely populated. Note internal anal sphincter (white arrow) and external anal sphincter (black arrow).

View larger version (150K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B. —35-year-old woman with normal anal canal who was referred for investigation of proctalgia. Transvaginal sagittal sonogram shows entire length of anal canal.

View larger version (164K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A. —42-year-old man with remote total colectomy and ileoanal pouch for ulcerative colitis. Normal transperineal transverse sonogram of mid anal canal was obtained with conventional transvaginal probe.

View larger version (171K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B. —42-year-old man with remote total colectomy and ileoanal pouch for ulcerative colitis. Sagittal transperineal sonogram shows normal anal canal.

All fluid collections, sinus tracts, and fistulas were described by their location in relation to the internal and external sphincter, according to the classification system of Parks et al. [3]. The opening of any fistulous tract in the rectum, anal canal, vagina, or perineal skin was described with the 12 o'clock position directed anteriorly as in standard cross-sectional imaging. An internal opening was defined as an opening into the rectum or anus, whereas an external opening was defined as an opening on the perineum at physical examination. Because by definition, a fistula is an abnormal communication between any two epithelial lined surfaces, any tract which was blind-ending and did not have both an external and internal opening was labeled as a sinus tract. Defects in the sphincter mechanism were also recorded. Clinical charts were retrospectively reviewed to obtain additional clinical history and to determine the course of treatment and operative findings if any.

Results

Top Abstract Introduction Subjects and Methods Results Discussion References

 
All patients underwent sonography that revealed abnormal findings. Forty-six (85%) of 54 patients had fistulas or sinus tracts classifiable according to the system of Parks et al. [3] (Table 1). Fifteen (33%) of 46 patients also had perianal abscesses. Sonography revealed 33 transphincteric (Fig. 4A,4B), seven intersphincteric (Fig. 5), and six extrasphincteric tracts.

View larger version (121K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4A. —35-year-old woman with history of perianal abscess. At physical examination, external opening was noted on perineum. Findings on contrast sinogram were negative. Transverse sonogram of mid anal canal shows transphincteric fistula (arrow) extending posteriorly into abscess collection (arrowhead).

View larger version (121K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4B. —35-year-old woman with history of perianal abscess. At physical examination, external opening was noted on perineum. Findings on contrast sinogram were negative. Oblique transperineal sonogram shows portion of fluid-filled tract (arrows) extending from abscess (A) to external opening (double arrow) on perineum.

View larger version (132K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5. —45-year-old woman with no known history of bowel disease but with recurrent perianal abscess. Transverse transvaginal sonogram of mid anal canal shows multiple blind-ending intersphincteric sinus tracts (arrow) and large horseshoe-shaped ischioanal abscess (arrowhead).

Eight patients had sonographic findings that were not classifiable according to the system of Parks et al. [3]. These included two anovaginal fistulas (Fig. 6A,6B), one rectovaginal fistula, one prolapsed internal hemorrhoid, and two perianal complex masses. In addition, there were two solid vascular perianal or perirectal wall masses, both in patients with previously documented anorectal suppuration.

View larger version (130K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6A. —43-year-old multiparous woman with previous subtotal colectomy for ulcerative colitis who was referred to rule out rectovaginal fistula. Oblique transverse sonogram obtained transvaginally shows defect in external and internal and sphincter (between arrowheads) and gas-filled fistulous tract (arrows) extending from lumen of anal canal to posterior vaginal wall.

View larger version (131K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6B. —43-year-old multiparous woman with previous subtotal colectomy for ulcerative colitis who was referred to rule out rectovaginal fistula. Transvaginal sagittal sonogram also shows gas-filled fistula (arrows) extending from lumen of anal canal to posterior vaginal wall.

Thirty (56%) of 54 patients had surgical intervention. Four patients with known Crohn's disease had either a proctocolectomy or a defunctioning ileostomy, preventing potential confirmation of preoperative sonographic findings. The sonographic findings were confirmed in 22 (85%) of the remaining 26 patients. Twenty patients had perianal fistulas or sinus tracts or both, the exact anatomic location and course accurately identified on sonography before surgery. Two perianal complex masses identified on transvaginal sonography were surgically excised, and pathologic evaluation revealed scar endometriomas.

In four of the 26 patients, the sonographic findings were not confirmed at surgery (Table 2). Three of the four had internal openings identified on sonography that were not confirmed at the time of surgery, although the location and course of any fistula or sinus tract in all these patients were confirmed (false-positive for internal opening only). In the fourth patient with Crohn's disease, sonography revealed a high intersphincteric sinus and a transphincteric fistula. Surgery confirmed the transphincteric fistula, but the intersphincteric sinus was actually a high intersphincteric fistula with a posterior opening into the rectum that was not detected on sonography (false-negative for internal opening only).

Of the remaining 24 patients who did not have surgery, three patients refused surgery, and six patients are awaiting surgery at this writing. Fifteen patients were treated conservatively. This nonsurgical subgroup included a perianal inflammatory mass and a rectovaginal septal mass, both in patients with a history of perianal suppuration. Thirteen of the 16 patients treated conservatively had complex perianal fistulas or sinus tracts or both caused by Crohn's disease.

Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Our results validate the use of the transperineal technique for imaging perianal disease. In three (75%) of four patients in whom surgery failed to confirm sonographic findings, an internal opening identified on sonography was not confirmed at surgery. However, if the cryptoglandular theory of origin for fistula in ano is correct, then a primary internal opening must have existed at some stage during the disease process in these patients. Perhaps the internal opening in these three patients closed at some stage in the interval between sonography and the surgical procedure, and this change explained the lack of confirmation. An alternative explanation is that sonography is actually more sensitive than direct visualization or probing when the openings are only a few millimeters. In fact, it is common to fail to identify at surgery the internal orifice in patients with perianal inflammatory disease. In one large surgical series, an internal opening was not found in 14% of patients [12].

In a fourth surgical patient, sonography failed to identify the posterior opening of an intersphincteric tract into the rectum. It did, however, visualize this tract and correctly depict an additional transphincteric tract. This patient illustrates one potential disadvantage of transperineal sonography; on occasion it may be limited in the assessment of high perirectal disease, particularly in male patients.

In our study, the incidence of the various types of fistulas or sinus tracts was as follows: intersphincteric, 15%; transphincteric, 72%; and extrasphincteric, 13%. The background incidence in the population is estimated as follows: intersphincteric, 70%; transphincteric, 23%; suprasphincteric, 5%; and extrasphincteric, 2% [3]. This discrepancy is most likely the result of a selection bias in our study population that included a large group of patients with inflammatory bowel disease. Fifty-two percent of the patients in this study had Crohn's disease, and these patients are much more likely to have more complex disease.

There are several advantages to imaging patients with perianal inflammatory disease. The differentiation between fistula-in-ano and associated abscess can be clinically difficult, particularly in patients with Crohn's disease, in whom occult sepsis is common and disease is often complex (Fig. 7A,7B,7C,7D). All collections should be surgically drained. There is little, if any, use for antibiotics in the primary treatment of perianal suppuration [1]. The discovery of a primary internal orifice is crucial because the most common cause of recurrence of fistula in ano is failure to eradicate the infected anal gland in the intersphincteric space. Sonography may be more sensitive for identifying an internal opening and may also reveal additional unsuspected tracts preoperatively. Again, failure to detect and treat lateral or upward extension also can lead to recurrence of disease.

View larger version (79K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7A. —18-year-old man with Crohn's disease and two previous surgeries for perianal suppuration who was referred to rule out occult infection. No external openings were seen on perineum. Sonography revealed complex disease. Transverse suprapublic sonogram at supralevator levels shows intramural fluid collection (arrow) with particulate debris in rectal wall.

View larger version (124K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7B. —18-year-old man with Crohn's disease and two previous surgeries for perianal suppuration who was referred to rule out occult infection. No external openings were seen on perineum. Sonography revealed complex disease. Sagittal transperineal sonogram shows posterior fluid collection (arrow) extending caudally in intersphincteric location to most inferior aspect of anal canal.

View larger version (144K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7C. —18-year-old man with Crohn's disease and two previous surgeries for perianal suppuration who was referred to rule out occult infection. No external openings were seen on perineum. Sonography revealed complex disease. Transverse transperineal sonogram of mid anal canal shows internal opening (arrowhead) posteriorly at 6 o'clock position. Bulk of caudal aspect of perianal and perirectal abscess (arrow) extends cranially in intersphincteric plane.

View larger version (112K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7D. —18-year-old man with Crohn's disease and two previous surgeries for perianal suppuration who was referred to rule out occult infection. No external openings were seen on perineum. Sonography revealed complex disease. Transverse transperineal sonogram more caudally in anal canal than C shows additional transphincteric sinus tract with internal opening at 11 o'clock position (arrow). This tract crosses both internal and external anal sphincter and extends into right ischioanal fossa at which it ends blindly.

Endoanal sonography has already been shown useful in the evaluation of perianal sepsis and fistula in ano [13]. However, placement of the rigid probe in the anal canal and rectum limits assessment of the perineal region because the perineum and the buttocks are on a plane caudal to the inferior aspect of the anal canal. In addition to providing a much larger field of view than endoanal sonography, transperineal sonography is also much better tolerated in patients with this condition, and the examination can be completed in approximately 20 min.

In our department, we have successfully implemented transvaginal and transperineal sonography as routine sonographic procedures for the evaluation of patients with any disease in the perianal region. The procedure is extremely well tolerated, and we believe that our findings support its value in rapid and accurate diagnosis. Although the learning curve to become proficient at performing anal canal evaluation in the male patient is substantial, most experienced abdominal sonographers achieve competency after approximately 12 patients.

References

Top Abstract Introduction Subjects and Methods Results Discussion References

 

1. Gordon PH. Anorectal abscesses and fistula-in-ano. In: Gordan PH, Nivatvongs S, eds. Principles and practice of surgery for the colon, rectum and anus. St. Louis: Quality Medical, 1992: 222-263
2. Kornbluth A, Salomen P, Sachar DB. Crohn's disease. In: Sleisenger MH, Fordtran JS, eds. Gastrointestinal disease: dathophysiology, diagnosis, management, 5th ed. Philadelphia: Saunders, 1993: 1276-1277
3. Parks AG, Gordon PH, Hardcastle JE. A classification of fistula-in-ano. Br J Surg 1976;63:1 -12[Medline]
4. Nielson MB, Hauge C, Pedersen JF, Christiansen J. Endosonographic evaluation of patients with anal incontinence: findings and influence on surgical management. AJR 1993;163:771 -775
5. Stewart LK, Wilson SR. Transvaginal sonography of the anal sphincter: reliable or not? AJR 1999;173:179 -185[Abstract/Free Full Text]
6. Senagore AJ, Milson JW, Talbott TM, Muldoon JP, Mazie WP. Intrarectal ultrasonography in the staging and management of rectal tumors. Am Surg 1988;54:352 -355[Medline]
7. Cataldo PA, Senagore A, Luchtefeld MA. Intrarectal ultrasound in the evaluation of perirectal abscesses. Dis Colon Rectum 1993;36:554 -558[Medline]
8. Myhr GE, Myrvold HE, Nilsen G, Thoresen JE, Rinck PA. Perianal fistulas: use of MR imaging for diagnosis. Radiology 1994;191:545 -549[Abstract/Free Full Text]
9. Haggett PJ, Moore NR, Sheaman JD, Travis SPL, Jewell DP, Mortensen NJ. Pelvic and perineal complications of Crohn's disease: assessment using magnetic resonance imaging. Gut 1995;36:407 -410[Abstract/Free Full Text]
10. Hertzberg BS, Bowie JD, Weber TM, Carroll BA, Kliewer MA, Jordan SG. Sonography of the cervix during the third trimester of pregnancy: value of the transperineal approach. AJR 1991;157:73 -76[Abstract/Free Full Text]
11. Rubens DJ, Strang JG, Bogineni-Misra S, Wexler IE. Transperineal sonography of the rectum: anatomy and pathology revealed by sonography compared with CT and MR imaging. AJR 1998;170:637 -642[Free Full Text]
12. Mazier WP. The treatment and care of anal fistulas: a study of 1000 patients. Dis Colon Rectum 1971;14:134 -144[Medline]
13. Law PJ, Talbot RW, Bartram CJ. Anal endosonography in the evaluation of perianal sepsis and fistula-in-ano. Br J Surg 1989;76:752 -755[Medline]

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This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stewart, L. K. Articles by Wilson, S. R. Search for Related Content PubMed PubMed Citation Articles by Stewart, L. K. Articles by Wilson, S. R. Social Bookmarking                      What's this? Hotlight (NEW!) What's Hotlight?