Learning objectives
This exhibit will review the aetiology,
relevant anatomy,
magnetic resonance imaging (MRI) sequences,
MRI appearances and classification of perianal fistulas,
and management options of perianal fistulas.
Background
Introduction:
Perianal fistulas are one of the many complications of Crohn’s disease and are often difficult to manage if not diagnosed correctly.
This may be due to occult sepsis not identified on probing or examination under anaesthesia by the surgeon.
For example,
they may be located within the pelvis from supralevator abscess/fistula formation.
Hence if treated incorrectly,
they can cause significant morbidity to the patient and decrease their quality of life(1).
It is important for radiologists to understand the pathophysiology of perianal fistulas and the...
Imaging findings OR Procedure details
MRI appearance and classification of perianal fistulas using the St James University Hospital Classification(1).
Grade 1 = simple intersphincteric fistula.
Fistulous tract extends from skin of perineum or natal cleft to the anal canal.
No ramification or abscess formation in the intersphincteric plane,
or involvement of the ishioanal or ischiorectal fossa is present.
The fistula is confined entirely within the external sphincter (Fig.
9 & 10).
Grade 2 = intersphincteric fistula with either ramification,
secondary sinus tract or abscess formation within the intersphincteric plane.
No...
Conclusion
Perianal fistulas contribute to significant morbidity in patients and are difficult to manage correctly if their relevant anatomy is not adequately identified.
As radiologists,
it is important to correlate imaging findings with the pathophysiology and anatomy of perianal fistulas so as to guide management options - either conservative medical therapy or with surgery.
Personal information
Dr.
Wei Che Tsai
Radiology Registrar (year 2)
Royal Hobart Hospital
Dr.
Aditya Varma
Consultant Radiologist
Royal Hobart Hospital
References
1.
Morris J,
Spencer JA,
Ambrose NS.
MR imaging classification of perianal fistulas and its implication for patient management.
RadioGraphics.
2000 May; 20(3):623-635.
2.
Chiari H.
Uber die analen divertikel der rectumschleimhaut und ihre beziehung zu den anal fisteln.
Wien Med Pres.
1878; 19:1482-1483.
3.Halligan S,
Stoker J.
Imaging of fistula in ano.
Radiology.
2006; 239(1):18-33.
4.
McColl I.
The comparative anatomy and pathology of anal glands.
Ann R Coll Surg Engl.
1967;40:36-67.
5.
Fucini C.
One stage treatment of anal abscesses and fistulae.
A...