- Goodsall's rule
Goodsall's rule relates the external opening of an
anal fistula to its internal opening. It states that the external opening situated behind the transverse anal line will open into the anal canal in the midline posteriorly. An anterior opening is usually associated with a radial tract.Fistula s can be described as anterior or posterior relating to a line drawn in thecoronal plane across theanus , the so called transverse anal line. Anterior fistulas will have a direct track into the anal canal. Posterior fistulas will have a curved track with their internal opening lying in the posterior midline of theanal canal . An exception to the rule are anterior fistulas lying more than 3 cm. from the anus, which may have a curved track (similar to posterior fistulas) that opens into the posterior midline of the anal canal.The investigation of choice for anal fistulas is
magnetic resonance imaging (MRI).References
* [http://www.surgical-tutor.org.uk/system/abdomen/perianal.htm "Perianal sepsis"] at Surgical Tutor
*cite book |title=Principles and Practice of Surgery for the Colon, Rectum and Anus |author=Philip H Gordon |publisher=Informa Health Care |year=2002 |pages=245 |isbn=0824742826 |url=http://books.google.com/books?id=4ZEeXDuknU0C&pg=PA245&lpg=PA245&dq=%22Goodsall's+rule%22+-wikipedia&source=web&ots=_eqp-frUIG&sig=bbt08BcFivLAUx8KYP1Qu95uQYE&hl=en
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