Fistula in ano or Bhagandar has been described one among the eight difficultly curable disease (Asta Mahagadas) by the Great Indian Surgery Sage Acharya Sushruta. Fistula presents usually in the form of a boil in an area nearby to anus (perianal region) which communicates through inside of anal canal or rectum. There are structures known as anal glands and anal crypts, located just inside the sphincter muscle of anus, inside the anal canal. When these anal gland or crypt gets infected or blocked, an abscess can form which advances towards the perianal skin and leads to the formation of a passage between perianal skin and inside of anal canal or rectum. This is known as track of Fistula and the disease is itself known as Fistula in ano or Anal fistula.

Anal fistulas commonly occur due to an anal abscess. An abscess is a collection of pus and infected fluid. An anal abscess usually develops after a small gland, just inside the anus, becomes infected with bacteria. A fistula may occur if an abscess has not completely healed, or if the infected fluid has not been entirely drained away. An anal fistula may also develop as a result of: A growth or ulcer (painful sore), an infected Fissure, a complication of surgery, a congenital abnormality (a health problem that you were born with).

Sometimes Anal fistulae are also a common complication of conditions that result in inflammation of the intestines. Some of these conditions include:

• Irritable bowel syndrome (IBS) : A chronic (long-term) disorder that affects the digestive system, causing abdominal pain, diarrhoea and constipation.
• Diverticulitis : The formation of small pouches that stick out of the side of the large intestine (colon), which become infected and inflamed.
• Ulcerative colitis : A chronic condition that causes the colon to become inflamed and can cause ulcers to form on the lining of the colon.
• Crohn's disease : A chronic condition that causes inflammation of the lining of the digestive system.

The diagnosis of the disease Fistula in ano can be made by a local examination by your physician. Usually the external opening is visible at any point in perianal region. Digital examination (Check-up by finger) gives an idea of possible site of internal opening while probing is the technique which is used to find out the direction and depth of Fistula track. Radiological investigations like Fistulography and / or MRI pelvis region, provide the information about the course of the Fistulous track.

Under local anaesthesia, the kshara sutra is inserted into the tract and the two ends of the thread are tied forming a loop. The alkalis coated on the thread are continuously released throughout the length of the track there by cutting, curetting, draining, cleansing (debridment) and healing the track. This therapeutic action of the thread lasts for seven days. The old thread is then replaced with a new thread by a special technique known as Rail road technique by the surgeon. Depending on the length and depth of the tract many sittings of kshara sutra may be required repeatedly and old thread is changed by the new one usually on weekly basis. The changing of the thread is a simple procedure taking about 2 to 5 minutes and usually requires no anaesthesia. Though the entire duration of treatment of Fistula in ano by kshara sutra may be longer than classical excision surgery, the safety, efficacy and the permanent results and the chances of recurrence and incontinence are almost nil, makes this treatment an ideal choice.