Pilonidal Sinus

By | June 10, 2022

The pilonidal sinus is also called the coccyx fistula. It is a cavity under the skin in the buttock crease area. This can lead to painful inflammation and even abscesses that have to be treated surgically.

What is a pilonidal sinus?

Chronic inflammation of the rima ani (buttock fold) is referred to as pilonidal sinus. The term comes from Latin. Sinus means depression or cavity. The term pilonidalis is made up of the words pilus and nidus. Pilus stands for hair. Nidus is translated as nest. The disease is also synonymously called pilonidal sinus, pilonidal cyst, coccyx fistula or sacral dermoid. For groin strain definitions, please visit definitionexplorer.com.

The pilonidal sinus occurs frequently with an incidence of 26 per 100,000 inhabitants per year. A disease peak is between the 20th and 30th year of life. Men are affected far more often than women. People with a sedentary job, such as drivers or office workers, have an increased risk of developing the disease. With an incidence of 150 to 100,000 Bundeswehr soldiers per year, the disease is particularly common in this population group.


The pilonidal cyst can be congenital or acquired. In the congenital variant, the opening of the neural tube remains after the embryonic period. This creates a connection between the anal edge and the tip of the coccyx, where inflammation can occur. This variant is very rare.

The acquired forms of the pilonidal sinus occur more frequently. Friction of the skin in the gluteal fold causes hair to penetrate the upper layer of the skin. There they encapsulate themselves. A cavity filled with hair develops under the skin. As a result, inflammation and abscesses can occur. Another form discussed is a hair formation disorder. Newly formed hair cannot penetrate the skin and thus forms a cavity that can become infected.

The development of a pilonidal cyst can also be caused by trauma. The cyst develops in a hematoma that has not healed. Risk factors for inflammation of the fistula are obesity and heavy sweating in the anal region. The warm, humid environment allows bacteria to multiply, penetrate the fistula and infect it.

Symptoms, Ailments & Signs

A pilonidal sinus without inflammation causes no symptoms. Only one or more fistula openings in the skin are visible. Invasion of bacteria into the pilonidal cyst leads to an acute infection. Swelling, overheating and reddening of the skin in the coccyx area occurs.

The swelling can take on a considerable size in the sense of an abscess in a short time. The patients complain of sometimes severe pain. Sitting may not be possible due to pain. Pus may come out. In the chronic course, the fistula continuously secretes pus or wound secretion. Patients notice contamination in their underwear. Pain can occur. There are no acute signs of inflammation. This form of the pilonidal sinus can progress to acute inflammation at any time.

Diagnosis & course of disease

The diagnosis is made on the basis of the medical history and a clinical examination. Patients report pain, swelling, or secretion. The examination reveals fistula openings and bloody or purulent discharges in the chronic form in the coccyx region. In acute inflammation, swelling, redness and overheating are noticeable.

In some cases, pus can be drained with pressure. If necessary, a fistula opening can be explored with the button probe. Severe pain in the acute infection and persistent pain and secretion in the chronic course justify the need for therapy.


The symptoms of a coccyx fistula can develop into serious complications if treated too late or incorrectly. In general, the pain increases as the disease progresses and eventually becomes permanent. The area around the coccyx is particularly affected and reacts painfully to pressure, resulting in poor posture and evasive movements.

Furthermore, abscesses can form and, in extreme cases, cause blood poisoning. The fistula itself can scar and cause permanent skin changes. Occasionally there are permanent sensory disturbances and signs of paralysis in the affected area. When surgically removing a coccyx fistula, there is a risk of bleeding and secondary bleeding. In the case of an open wound treatment, a superinfection can develop, in the course of which further fistula tracts develop.

Injuries to surrounding structures can also occur. If the sphincter is involved, transient incontinence may occur. Occasionally, one to two weeks after treatment, there is a discharge of wound fluid, which delays healing. Finally, the prescribed medication always carries the risk of side effects or interactions or allergic reactions.

When should you go to the doctor?

Pilonidal sinus disease should always be treated by a doctor. In most cases, the disease can spread to other parts of the body, making treatment essential. The sooner the doctor is consulted for pilonidal sinus, the better the further course. A doctor should be consulted if fistulas develop on the skin. In most cases, the affected areas are also slightly swollen or reddened. They can also itch and therefore have a very unpleasant effect on the quality of life of those affected.

If these symptoms occur, a doctor must be consulted in any case. Purulent discharge from these fistulas can also indicate pilonidal sinus and should also be examined by a doctor. Proper treatment is the only way to prevent further inflammation. In the case of pilonidal sinus, a general practitioner or a dermatologist can be consulted. The disease can be treated relatively well, and the patient’s life expectancy is not limited by the disease.

Treatment & Therapy

The treatment of the pilonidal sinus is surgical. Depending on the findings, inpatient or outpatient treatment can be useful. In the classic operation under general anesthesia, the fistula tract is visualized by staining it with methylene blue. The affected area is then cut out extensively. The wound can be closed with sutures or treated openly.

The course of the disease is shorter in closed wounds than in open ones. However, the anatomical position, which causes tension and friction on the wound, leads to wound healing disorders in 40 percent of cases. The naturally high bacterial colonization of the area also contributes to this. The recurrence rate with this procedure is high at 20 percent within three years.

In the case of open wound treatment, the course of the disease is longer, since the secondary wound healing of the mostly large wound can take several months. Daily wound care and regular wound checks are necessary. One advantage of open wound treatment is the significantly lower recurrence rate. Vacuum therapy can shorten the duration of secondary wound healing.

A sponge is inserted into the wound and it is sealed airtight with foil. A pump is connected via a tube, which creates a vacuum in the wound and continuously sucks off wound secretions. This treatment is only carried out in the inpatient area. Various surgical procedures are used to treat the pilonidal sinus.

Classically, the affected area is excised symmetrically to the midline. However, due to the anatomical location, recurrences often occur. An asymmetric excision, as in the Karydakis surgical procedure, can reduce the recurrence rate. Flaps and endoscopic procedures are also treatment options.


The formation of the pilonidal sinus can be prevented by permanently removing the hair in the coccyx region using laser epilation. Conventional hair removal is not enough because the hair is not completely removed. While the wound is healing after an operation, the affected area should be shaved extensively and consistently.


After the successful removal of a pilonidal sinus (coccyx fistula), good follow-up treatment is essential to prevent the development of secondary diseases and the recurrence of a pilonidal sinus. For this purpose, the scarred skin tissue at the operated site should be regularly examined by the dermatologist and/or attending surgeon for residual or new inflammation in the subcutaneous tissue.

If there is a suspicion that another focus of inflammation has developed under the skin, the additional use of imaging methods (MRT) for diagnosis and the renewed surgical removal of the affected tissue may be necessary. In addition, the inflammatory values ​​in the blood should be checked regularly in order to be able to identify and treat new foci of inflammation in the body at an early stage.

Since a pilonidal sinus that has occurred once, especially if it is chronically recurring (recurring), increases the likelihood of further chronic inflammatory skin diseases (acne inversa), good and regular skin hygiene should be maintained to prevent infection of the skin with bacteria ( Staphylococcus aureus) to avoid.

This includes daily showering and intensive hand disinfection. In addition, permanent hair removal using laser epilation and not smoking can help to prevent the disease or other chronic inflammatory skin diseases from breaking out again. Overweight patients should also aim to lose weight, since being overweight also increases the risk of developing a pilonidal sinus.

You can do that yourself

The coccyx fistula must be surgically removed. For this reason, the possibilities of self-help are limited to supporting one’s own health in coping with the initiated therapy. In addition, the existing fistula often causes inflammation. The person affected should therefore do everything possible to support their body’s own defense system. The more stable and healthier the immune system is, the better it can assert itself against pathogens.

This is helpful in the development of a possible secondary disease and in coping with the healing process after the surgical intervention. With a healthy and vitamin-rich diet, the affected person contributes a lot to strengthening the body’s own defenses. Sufficient exercise, avoiding obesity and participating in sporting activities are also helpful in the recovery process. In order for the body to be able to regenerate itself sufficiently, sleep hygiene must be optimally designed. A good sleeping and waking rhythm, sufficient oxygen and continuous sleep are beneficial. At the same time, the consumption of harmful substances such as alcohol and nicotine should be avoided.

Mental strength also helps to better deal with the disease. The person concerned can use relaxation methods to reduce stressors and experience mental relief. It is particularly important to work with a doctor so that possible changes or complications can be identified as quickly as possible.

Pilonidal Sinus