Risk of re‐operation after Bascom I for pilonidal sinus disease. A Danish population‐based cohort study

BACKGROUND: The treatment of chronic pilonidal sinus disease (PSD) is controversial. Minor PSD can be treated minimally invasively. The preferred minimally invasive treatment in Denmark is the Bascom I procedure. AIM: To evaluate re-operation rates following elective Bascom I and to identify potential risk factors. METHODS: Using nationwide Danish databases from 2010 to 2021, we identified patients diagnosed with PSD undergoing incident Bascom I. Based on previous surgery, patients were divided into four groups: (i) Bascom I with no previous PSD treatment; Bascom I with history of (ii) one or (iii) two incision & drainage (I&D) procedures; and (iv) Bascom I with history of other PSD procedures. Patients were followed until re-operation, death or emigration. Stratified by sex, 1-, 2- and 5-year risk of re-operation was examined. A subsequent analysis assessed the risk of re-operation after second Bascom I procedure. RESULTS: Of 3555 (79% male) PSD patients undergoing Bascom I procedure, 2417 had the procedure without previous PSD surgery, 382 underwent Bascom I after one I&D procedure, 108 after two I&D procedures and 648 after other/more PSD procedures. The overall 5-year re-operation risk was 30%, highest in younger age groups. As much as 65% of re-operations occurred within the first 12 months. After a second Bascom I, the 5-year risk was 45%. CONCLUSION: High rates of early failures seem to drive a high risk of re-operation after the Bascom I procedure. Patient selection, technique and training likely need improvements to ensure acceptable outcomes.