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Anal diseases (final)
- 1. ANAL DISEASES PRESENTED BY DR. AASEF MANSOOR SUPERVISED BY DR. NEELAM MALIK AND DR. NAWAL AL HAMMAR
- 2. Objectives Understanding the : Pathophysiology and classification of the anal fistulas and anal carcinomas in brief. To be familiar with the role of fistulograms , ultrasounds , PET and MRI.
- 3. ANATOMY The anal canal is a cylindrical structure surrounded by two muscular layers, the internal and external sphincters. The internal sphincter is composed of smooth muscle, the fibers of which are continuous with the circular smooth muscle of the rectum The external sphincter is composed of striated muscle and has posterior attachments to the anococcygeal ligament and anterior attachments to the perineal body and urogenital diaphragm. The two sphincters are separated by the intersphincteric space, which contains fat, areolar tissue, and the longitudinal muscle. This space forms a natural plane of lower resistance in which fistulas and pus can readily spread.
- 4. ANAL FISTULAS Basically an anal fistula is a tract that connects an anal ( or rectal ) internal opening with an external opening ( perianal skin).
- 6. Etiology and Pathogenesis Primary causes : The most common cause is due to obstruction of anal gland which leads to stasis and infection with abscess and fistula formation. Or they may be secondary to: Surgery (eg. hemorrhoideal surgery) Inflammatory bowel diseases ( eg. Crohn's disease) diverticulitis Infections (viral, fungal or TB) trauma during childbirth Malignancy radiation therapy
- 7. CLINICAL FINDINGS Chronic draining abscess Pain with defecation Pruritis ani O/E : Erythema , induration and excoriated skin.
- 8. RADIOLOGICAL ASSESSMENT Simple fistulography Endo –anal ultrasound MRI ( golden standard )
- 10. Fiistulogram of a male patient showing several high extensions surrounding the anorectal junction Limitations: The pelvis floor ( levator ani muscles ) cannot be visualized directly. The exact level of the internal opening in the anal canal is often impossible to determine with sufficient accuracy The sphincter muscles themselves are not directly imaged. ??Supra- or an infralevator location. Acute tracks may not have a patent lumen. Locating these extension is central for surgical management.
- 13. EAUS – TRANSSPHINCTER IC FISTULA AT 7 O’CLOCK
- 20. Classification of Perianal Fistulas The most widely used classification is the Parks Classification which distinguishes four kinds of fistula:
- 21. PARKS CLASSIFICATION. A = Intersphincteric (45%) B = Transsphincteric (30%) C = Suprasphincteric (20%) D = Extrasphincteric The most common fistulas are the intersphincteric and the transsphincteric. The extrasphincteric fistula is uncommon and only seen in patients who had multiple operations. In these cases the connection with the original fistula tract to the bowel is lost. A superficial fistula is a fistula that has no relation to the sphincter or the perianal glands and is not part of the Parks classification. These are more often due to Crohns disease or anorectal procedures such as haemorrhoidectomy or sphincterotomy.
- 22. Reporting When describing a fistula, it is important to mention the following characteristics: -Position of the mucosal opening on axial images (using the anal clock). -Distance of the mucosal defect to the perianal skin on coronal images. -Secondary fistulas or abscesses. The drawing illustrates the anal clock, which is the surgeon's view of the perianal region when the patient is in the supine lithotomy position. This scheme corresponds to the orientation of axial MR images of the perianal region.
- 23. Examples of Perirectal Fistulas Intersphincteric fistula T2W images with and without fat saturation. An intersphincteric fistula is located at 6 o'clock. Continue with coronal images.
- 24. On the coronal image the fistula runs caudally towards the skin. There is no connection with the external sphincter.
- 25. Transsphincteric fistula Axial T2WI and T2WI + fatsat of a transsphincteric fistula. The defect through the internal and external sphincter at 6 o'clock is clearly visible and more apparent on the fat sat images.
- 26. Axial T2W-fatsat images of a transsphincteric fistula with the mucosal opening at 11 o'clock.
- 27. An example of a suprasphincteric fistula. There are two tracts in the ischioanal region. The right sided tract runs over the puborectal muscle (asterisk) and the mucosal opening lies at the level of the linea dentata (black arrow).
- 28. Extrasphincteric fistula Coronal T2W-images of a small abscess in the left ischioanal fossa, the fistula runs through the levator ani. It is therefore above the sphincter complex and extrasphincteric.
- 29. Complex Fistula Two tracts in the left buttock form a single tract (no. 1-2). This fistula breaks through the external sphincter (no. 4). In the intersphincteric space it divides again into two tracts (no. 5). One ends blindly in the intersphincteric space (no. 6). The other breaks through the internal sphincter with the mucosal defect at 1 o'clock.complex fistula
- 30. Crohn's disease Patient with a perianal fistula who has Crohn's disease Axial fatsat images depict the transmural inflammation with infiltration of the mesenteric fat. Coronal images shows the thickening of the bowel wall
- 31. Fistulography Fistulography is a traditional radiologic technique used to define the anatomy of fistulas, yet it is an unreliable technique and is difficult to interpret. Ultrasonography The benefits of ultrasonography over MRI are the former's ubiquity and lower operating costs MRI MRI is the imaging modality of choice.
- 32. Treatment Seton fistulotomy Fistulotomy Fistulectomy This patient was already known to have an interspinchteric fistula, the mucosal defect is at 1 o'clock. In the tract there is a linear structure with a low signal intensity. This is the Seton which was inserted to treat the fistula.
- 33. ANAL CARCINOMA
- 34. EPIDEMILOGY Anal cancer is a relatively uncommon malignancy & accounts for only 1 – 2 % of all large bowel malignancy. Ratio of 1:2 for men to women. Median age is 60 yrs. RISK FACTOR HIV infection Immunosuppression The number of lifetime sexual partners, and receptive anal intercourse Smoking In females: previous in situ or invasive cervical, vulval or vaginal cancer.
- 35. Clinical Presentation Approximately 45% of patients may present with bleeding per rectum. Around 30% of patients may have pain and/or a sensation of a mass.
- 36. Pathology Anal carcinoma typically originates between the anorectal junction above and the anal verge below. The vast majority of anal canal cancers are squamous cell cancers.
- 37. Imaging Modalities •MRI and PET/CT scan
- 39. Early T1 anal tumor MR image shows that normal low signal of anal canal muscle has been replaced by intermediate- signal tumor (arrow) that is less than 2 cm.
- 40. T2 Anterior Anal canal carcinoma. -MR image shows that lesion measures >2 cm and < 5cms. -There is invasion of external sphincter (arrow).
- 41. T3 Anal Carcinoma - Size more than 5 cm. - No evidence of adjacent organ invasion, as evidenced by complete low-signal rim (arrowheads) separating tumor from prostate anteriorly.
- 42. T4 anal cancer MR image shows lobulated tumor with invasion into posterior vagina (arrow).
- 43. T4 Anal Carcinoma + nodal & organ metastasis - Size More than 5cms and invasion into adjacent organs. - Inguinal nodal metastases. - Bilateral enhancing perirectal adenopathy (arrows)
- 44. FDG PET/CT alters staging…
- 45. Conclusion… • MR imaging has emerged as the imaging technique of choice for preoperative evaluation of perianal fistulas and anal carcinomas providing a highly accurate, rapid, and noninvasive means of performing pre-surgical and post treatment assessment. • FDG PET/CT alters staging of anal carcinoma in approximately 20% of cases and treatment intent in approximately 3–5% of cases.
- 46. THANK YOU
Editor's Notes
- This is how it actually looks like…….
- This is what the surgeon sees . The external openings…. What is actually important is the internal opening and their extensions…
- Extensions from the primary tract may fail to fill with contrast material if they are plugged with debris, are very remote, or there is excessive contrast material reflux from either the internal or external opening • the sphincter muscles themselves are not directly imaged, which means that the relationship between any tract and the sphincter must be guessed • difficult to decide whether an extension has a supra- or an infralevator location • the exact level of the internal opening in the anal canal is often impossible to determine with sufficient accuracy • Acute tracks may not have a patent lumen • Difficult to relate the track to the sphincter and levator ani • Shown to be accurate in only 16 % • cannot distinguish between the different types of fistula and its exact course through/in between anal sphincters and also fails to know the integrity of sphincters
- Water soluble iodine dye is used.
- This can be used intraoperatively.
- Intersphincteric fistulas accounted for 45% of cases. These fistulas ramify only in the inter-sphincteric space and do not traverse the external sphincter, which forms a relative barrier to the spread of infection. The track runs along the longitudinal muscle layer between the internal and external sphincters and may reach the perianal skin through or medial to the subcutaneous external sphincter. In transsphincteric fistulas (30% of cases in the study), the track passes from the intersphincteric space through the external sphincter into the ischiorectal fossa. In suprasphincteric fistulas (20% of cases in the study), the track progresses upward into the intersphincteric space, passes over the top of the puborectalis muscle, then descends through the levator plate to the ischiorectal fossa and finally to the skin. In extrasphincteric fistulas, the track passes from the perineal skin through the ischiorectal fossa and levator muscles then into the rectum. Thus, this fistula lies completely outside the external sphincter complex.
- Anal fistulas are classified according to their progression relative to the anal sphincter and pelvic floor structures. To locate the point of origin and describe the direction of the fistulous track, we use an “anal clock” scheme, which is the same as that used by surgeons to describe injuries around the anal region
- When you see fistulas track passes from the perineal skin through the ischiorectal fossa and levator muscles then into the rectum… Think of Crohns disease
- References can be provided
- Seton fistulotomy is a technique where a rubber ligature or vessel loop is pulled through the fistula, it then is tightened every 2 weeks or so in order to obtain pressure necrosis so that the Seton is slowly pulled through the muscle. This has the advantage that the muscle is slowly cut and fibroses at the same time in order to cause as little damage as possible to the sphincter complex.
- MRI has become the imaging modality of choice for locoregional staging and assessment of tumor response after chemoradiotherapy. MRI provides high-resolution multiplanar information about the location, size, circumferential and craniocaudal extent of the primary tumor and information regarding the involvement of adjacent structures. FDG PET/CT has an increasing role in staging and treatment planning of anal carcinoma, particularly because up to 98% of anal tumors are FDG-avid. At diagnosis, FDG PET/CT is used to evaluate primary tumor size, lymph node status, and whether distant metastases are present. FDG PET/CT can also be useful for planning radiation therapy by clearly defining sites of metabolically active tumor. .
- Increased FDG uptake (arrow) and metabolically active right inguinal node, pelvic side wall lymph node and distant liver metastasis…