anal fistula

Fistula-in-Ano

Anal fistula symptoms: These complaints make you sit up and take notice

Moisture, blood, pus or unpleasant odour at the anus

The anal fistula can become quite acutely noticeable with an anal abscess. After the surgeon opens the abscess, the pain subsides. Despite the best care, the wound does not heal completely and a small opening or a non-healing pimple remains? This is highly suspicious of an anal fistula! Also, if an abscess occurs repeatedly in the same place, anal fistula is the most likely cause.

Sometimes the symptoms also start insidiously: if there is dampness and itching, you might first think of haemorrhoids. Even after careful hygiene, the anus never stays clean for long; one discovers traces of blood or purulent secretion in the laundry. Sometimes a patient also notices the uncontrolled discharge of intestinal gases or traces of stool via the external fistula opening.

Anal fistula - what is it?

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). 

Royal anal fistula: Sun King Louis XIV

Anal fistula history: In prominent company

From Louis XIV to Charles Dickens

The oldest descriptions of anal fistulas date back to the 4th Pharaonic Dynasty in 2600 BC in Egypt. Sushruta in India around 600 BC and Hippocrates in Greece around 400 BC treated fistulas with textile drainages 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 of Arderne (1307 - 1370). 

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 best-known patients was author Charles Dickens, whose gratitude led to funding for the hospital extension from Lord Iveagh, a member of the Guinness Brewery dynasty. After the conversion, the hospital in City Road was named "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), he then founded the Parks then established the still recognised theory of the cryptoglandular origin of anal fistulas and the classification of these fistulas depending on their positional relationship to the sphincter muscle. He was able to prove that the intersphincteric glands located between the two concentric muscle rings of the internal and external sphincter are the cause of the vast majority of anal fistulas and have an excretory duct running through the internal sphincter. He identified tuberculosis, which was still more common at the time, and chronic inflammatory bowel diseases such as Crohn's disease as rare causes.

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).
  • A fistula tract that begins at the inner fistula opening and ends blindly is called an incomplete anal fistula. It often causes few symptoms for a long time and suddenly becomes conspicuous by pain, noticeable hardening or an acute abscess. An episode of diarrhoea is often the trigger for acute symptoms.

A sustainable cure of an anal fistula without surgery is not to be expected. Nevertheless, some therapeutic approaches can be of importance in individual cases:

  • Wait and see, do nothing: If an anal fistula does not cause any complaints apart from the occasional secretion of small amounts of fluid, wait-and-see observation may be sufficient in individual cases.
  • Antibiotics: Antibiotics as systemic treatment will not cure an anal fistula, but they reduce inflammatory activity. This results in a place sometimes as a bridging treatment when inflammation increases and immediate surgical therapy is not available or desired. In patients with inflammatory bowel disease, long-term treatment with antibiotics may be the best therapeutic option if surgical repair of the fistula is not possible. Topical treatment with the antibiotic metronidazole is occasionally recommended for delayed wound healing after surgery.
  • Antibodies, "biologicals": The immunomodulators used in the treatment of chronic inflammatory bowel diseases can, in individual cases, reduce the activity of an anal fistula to such an extent that a good quality of life can be achieved.

If the level of discomfort is high enough, surgery is unavoidable. Please visit our page about the different surgical procedures.

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.

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