Goodsall's rule
Goodsall's rule relates the external opening (in the perianal skin) of an anal fistula to its internal opening (in the anal canal). It states that if the perianal skin opening is posterior to the transverse anal line, the fistulous tract will open into the anal canal in the midline posteriorly, sometimes taking a curvilinear course. A perianal skin opening anterior to the transverse anal line is usually associated with a radial fistulous tract.[1]
Or in more direct terms, it means that anterior-opening fistulas tend to follow a simple, direct course while posterior-opening fistulas may follow a devious, curving path with some even being horseshoe-shaped before opening in the posterior midline.[2]
According to a study on patients undergoing operations for cryptoglandular anal fistulas, 92.9% of fistulas within 1.5 cm followed the Goodsall rule, whereas only 47.4% followed it beyond 3.6 cm.[3]
In situations where there are multiple anal fistulae, the course would be similar to that of posterior-opening fistulae because of branching and communication between these openings.[citation needed]
The investigation of choice for anal fistulas is magnetic resonance imaging (MRI). Fistulograms can be used to demonstrate the track of the fistula.
Goodsall's rule is named after David Henry Goodsall who described it in 1900.
References
- Perianal sepsis at Surgical Tutor
- Philip H Gordon (2002). Principles and Practice of Surgery for the Colon, Rectum and Anus. Informa Health Care. p. 245. ISBN 0-8247-4282-6.
- ^ "Goodsall's Rule". UpToDate. Retrieved 8 April 2023.
- ^ Burgess BE. Chapter 88. Anorectal Disorders. In: Tintinalli JE, Stapczynski JS, Cline DM, Ma OJ, Cydulka RK, Meckler GD, eds. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill; 2011. http://www.accessmedicine.com/content.aspx?aID=6361536. Accessed June 14, 2012.
- ^ Cuiñas, K. "PTU-196 Goodsall's rule – past its sell-by date?". Gut.