Short-term clinical outcomes following crystallized phenol treatment for recurrent pilonidal sinus: a prospective uncontrolled cohort study

Crystallized phenol is used as a minimally invasive treatment for pilonidal sinus disease. Evidence describing short-term outcomes in patients with recurrent disease remains limited. This study describes wound healing, postoperative symptoms, and pain scores after crystallized phenol treatment in a small uncontrolled cohort. This prospective uncontrolled cohort included 31 patients with recurrent pilonidal sinus following previous surgery. All patients received crystallized phenol treatment. Complete healing was defined as closure of the sinus opening and cessation of discharge. Healing within four weeks was examined as an exploratory descriptive category because this threshold was not prespecified. Pain was assessed using a visual analogue scale (VAS) on the day after treatment and at weeks 1 and 2. No pretreatment VAS measurement or concurrent control group was available. Complete healing within four weeks was documented in 18/31 patients (58.1%); 11 (35.5%) healed after four weeks and 2 (6.5%) had no documented healing. Pruritus was reported by 28 patients (90.3%) and burning sensation by 9 (29.0%); no abscess or collection was documented during follow-up. Mean postoperative VAS scores were 3.81 ± 1.37 on the day after treatment, 1.13 ± 0.84 at week 1, and 0.84 ± 0.82 at week 2. These observations describe postoperative pain over time and do not establish a phenol-specific analgesic effect. This small uncontrolled cohort provides a descriptive account of short-term outcomes after crystallized phenol treatment for recurrent pilonidal sinus. The observed postoperative decline in VAS scores cannot be attributed specifically to phenol, and conclusions about comparative effectiveness and safety are limited by the lack of a control group and incomplete characterization of adverse events. Larger comparative studies with standardized outcome assessment and longer follow-up are needed. Trial registration Iranian Registry of Clinical Trials (IRCT), IRCT20130826014483N13. Registered on 2025–08-05. URL: https://www.irct.ir/search/result?query=IRCT20130826014483N13