What are the differences between high and low anal fistulas?

High-position anal fistula and low-position anal fistula are two completely different anorectal diseases. To correctly distinguish them, you need to start with the lesion. Generally, the one above the deep part of the muscle is high-position, and the one below is low-position, so the treatment methods are also different. However, there are many similarities between the two, mainly manifested as pus discharge, pain, itching, nodules or scars, etc. There are also systemic symptoms, such as weight loss, anemia, constipation, etc.

1. Distinguishing between high and low anal fistula

If you want to make a strict distinction between high and low anal fistulas, you only need to understand them from the lesions. The lesion is also called the fistula. At the beginning of the formation of the fistula, there is usually only one lesion, which is called the main focus. As the disease progresses, multiple small fistulas, called tributaries, may develop. There are two types of main stove structures. One is that the pipe is quite long, the inner mouth is deep, and the extension range is very wide. The other is that the pipe is quite short, the inner mouth is shallow, and the extension range is limited. Anal fistulas with an opening above the deep external anal sphincter are high-position anal fistulas, while anal fistulas with an opening below the deep external anal sphincter are low-position anal fistulas.

2. Common Performance

1. Pus discharge: Pus discharge is the main symptom. Generally speaking, newly formed fistulas discharge more pus, which is thick, yellow and smelly. Fistulas that have been in existence for a long time will discharge relatively less pus, or it may come and go and be as thin as water. If the amount of pus increases, it means that a new fistula has been formed. The fistula is sometimes temporarily blocked and pus is not discharged, resulting in local swelling and pain and increased body temperature. Later, the blocked fistula will rupture and pus will be discharged again. Gas or feces may also be discharged from the fistula.

2. Pain: When the fistula is unobstructed and there is no inflammation, there is generally no pain, only a slight swelling in the anus, which may worsen when walking. If the external opening is closed, pus accumulates in the fistula, or feces enters the fistula, the pain will worsen or the pain will worsen during defecation. For internal blind fistula, there is often a burning discomfort in the lower rectum and anus, and the pain worsens during defecation.

3. Itching: The skin of the anus often feels itchy due to irritation from pus and other discharges.

4. Nodules or scars: Due to repeated stimulation of the fistula wall and fistula opening, fibrous tissue proliferates and tough connective tissue is formed on the wall and fistula opening. It often manifests as discoloration of the skin around the fistula, epidermal shedding, depression and deformation, and the presence of cord-like nodules leading to the anus.

5. Systemic symptoms: Most cases have no systemic symptoms. When the anal fistula invades a large and deep area or has many branches, repeated inflammation and infection will lead to systemic symptoms such as weight loss, anemia, constipation, and difficulty in defecation.