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ANAL FISTULA - FISTULA IN ANO

Anal fistula - Definition

A fistula (lat. tube, pipe) describes a tubular duct, which is usually the result of a chronic, inflammatory process. The anal fistula in the true sense of the word has its origin in the anal canal and pierces variable parts of the sphincter muscle. Rarer forms of fistula originate from higher intestinal sections (rectal fistula) or are caused independently of the anal canal by impaled hair (sine pilonidalis) or systemic inflammation (acne inversa). 

The oldest descriptions of anal fistulas date back to the 4th Pharaonic Dynasty 2600 BC in Egypt. Sushruta in India around 600 BC and Hippocrates in Greece around 400 BC treated fistulas with textile drains impregnated with extracts from medicinal plants.

The surgical treatment of anal fistula goes back to the Frenchman Guy de Chauliac (1300 - 1368) and his British colleague John von Arderne (1307 - 1370).

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Royal anal fistula: Sun King Louis XIV

Probably the most prominent fistula patient in history was Sun King Louis XIV. Charles Francois Felix freed him from his suffering by fistula splitting in 1686. The successful surgeon was elevated to the nobility and was henceforth allowed to call himself Felix de Tassy, furthermore he was granted land and the sum of 300,000 francs.

In 1835 Frederic Salmon opened the first specialist clinic for anal fistula in London. One of his most famous patients was author Charles Dickens, whose gratitude led to the financing of the clinic's expansion by Lord Iveagh, a member of the Guinness Brewery dynasty. After the reconstruction, the hospital on City Road was given the name "St. Mark's Hospital for Fistula and other Diseases of the Rectum" (Video Prof. Robin Philipps), today one of the most renowned colorectal departments in the world.

Hippocrates still believed that a local trauma, for example while riding or rowing, would lead to a bruise which would then become festering. In the Middle Ages, knights were considered particularly at risk of developing anal fistula because they spent long periods in the saddle wearing heavy armour.

1878 discovered Chiari small glands in the wall of the anal canal (the proctodeal glands). He suspected that an infection of these glands could lead to anal fistula. Studies of Desfosses (1880) and Johnson (1914), who were able to demonstrate lymphatic tissue around the excretory ducts of the proctodeal glands.

Building on the work of Lockhart-Mummery (1929) and Eisenhammer (1958), the Parks then the theory of the cryptoglandular development of anal fistulas, which is still accepted today, and the classification of these fistulas depending on their positional relationship to the sphincter muscle. He was able to prove that the "intersphinctary" glands located between the two concentric muscle rings of the inner and outer sphincter are the cause of the vast majority of anal fistulas and have an excretory duct running through the inner sphincter. As rare causes he identified tuberculosis, which was even more common at that time, and chronic inflammatory intestinal diseases such as Crohn's disease.

Sir Alan Parks, founder of the modern theory and classification of anal fistula © St. Marks Hospital Foundation

A distinction is made between the complete anal fistula, in which a tunnel leads from an inner opening in the anal canal to the skin surface, and the incomplete fistula, in which the outer opening is missing.

  • The symptoms of complete anal fistula result from the secretion of fluid, pus or blood. The moisture leads to irritation of the skin, called irritant anal eczema with itching and traces of blood on the toilet paper. The secretion of pus may cause an unpleasant odour, which can be a first symptom. Bleeding scares the patient most and should always be the reason for an endoscopic examination of the colon (colonoscopy).

The fistulotomy is probably more suitable than surgeons or patients are willing to accept.

Phil J. Tozer, Consultant Colorectal Surgeon to St Marks Private Healthcare (2020). Expert Commentary on Perianal Fistulas. Diseases of the Colon & Rectum, 63(2), 133-134.

Michael R.B. Keighley, Norman S. Williams (Eds.): Keighley & Williams' Surgery of the Anus, Rectum and Colon, Fourth Edition. CRC Press, 2018, ISBN 1351105027, Chapter 10, Anorectal Abscess and Fistula

Chiari H. (1878): On the anal diverticula of the rectal mucosa and their relation to anal fistulas. Med Yearbooks 1878;8;419-27

Hermann G., Desfosses L. (1880): Sur la muqueuse de la region cloacale du rectum. Acad Sc 1880; 90:13017-2

Parks, A., & Morson, B. (1962). Fistula-in-Ano [Abridged]. Proceedings of the Royal Society of Medicine, 55(9), 751-758.