The injection of phenol (carbolic acid) is one of the oldest methods of treating the tailbone fistula and was first described in a publication in 1964.
The mostly 80 % phenolic solution is injected into the fistula and should lead to scarring and healing of the fistula due to an inflammatory reaction. According to the literature, the procedure is said to have healing rates between 30 and 92 %. The treatment is carried out on an outpatient basis under local anaesthetic and is only associated with a short period of absence from work and leisure activities.
In the last 15 years, numerous studies on this procedure have appeared, mainly from Turkey. However, the studies hardly permit a meaningful evaluation of the procedure on the basis of the quality criterion "fistula recurrence", i.e. recurrence of a fistula after phenol instillation. This is because the disease stages differed from study to study: Sometimes patients with purulent secretion or previous operations were excluded, in other studies they were also considered. Some patients were treated with phenol only once, others several times. In others, in addition to phenol injection, additional surgical measures were performed on the fistulas. Differences probably also result from the use of phenol in liquid or crystalline form as in the following film example:
The term "fistula recurrence" was also defined inconsistently or was completely absent. The proportion of patients for whom the fistulas did not heal after the first injection and further injection treatments had to be carried out is strikingly high at 70%. After multiple injections, the recurrence rate (however defined) was 5%. However, the varying length of follow-up periods, which ranged from 14 to 56 months depending on the study, is problematic, which hardly allows a reliable statement on the quality of the procedure and explains recurrence rates of between 9 and 40 %.
Studies in which phenol injection was compared with other treatment methods of the tailbone fistula hardly exist. In two older studies from 1975 and 1989, the phenol treatment performed significantly worse than other treatment methods. However, a recent American guideline recommends phenol injection for selected cases.
Phenol injection is one of the oldest treatment methods for tailbone fistula. Compared to the low burden on the patient (outpatient treatment under local anaesthesia, low downtime), the procedure can be considered for selected cases, as the cure rate is acceptable in these selected cases ("small findings").
Phenol is not approved in Germany because of its high toxicity and possible absorption into the body.
Literature sources:
Maurice BA, Greenwood RK (1964) A conservative treatment of pilonidal sinus. Br J Surg 51:510– 512
Dogru O, Camci C et al (2004) Pilonidal sinus treated with crystallized phenol: an eight-year experience. Dis Colon Rectum 47:1934–1938
Kaymakcioglu N, Yagci G et al (2005) Treatment of pilonidal sinus by phenol application and factors affecting the recurrence. Tech Coloproctol 9:21–24
Olmez A, Kayaalp C et al (2013) Treatment of pilonidal disease by combination of pit excision and phenol application. Tech Coloproctol 17:201–206
Aygen E, Arslan K et al (2010) Crystallized phenol in nonoperative treatment of previously operated, recurrent pilonidal disease. Dis Colon Rectum 53:932–935
Shorey BA (1975) Pilonidal sinus treated by phenol injection. Br J Surg 62:407–408
Stansby G, Greatorex R (1989) Phenol treatment of pilonidal sinuses of the natal cleft. Br J Surg 76:729–730
Steele SR, Perry WB et al (2013) Practice parameters for the management of pilonidal disease. Dis Colon Rectum 56:1021–1027
Bruce RM, Santodonato J et al (1987) Summaryreview of the health effects associated with phenol. Toxicol Ind Health 3:535–568
