KEY POINTS: - Our goal was to indentify the most common and most influential postoperative reasons causing persistent ABG. Our focus was concentrated on the mechanical dysfunctions in the middle ear, with special regard to postoperative fibrosis formation. - Periprosthetic adhesion formation was seen in 64% of the cases, and it was the primary cause behind the unsatisfactory hearing result in 32% of all cases - There was no significant difference in the level of persistent ABGs across groups of fibrosis and surgical failure after primary surgery - Periprosthetic fibrosis is the most common reason for compromised audiological outcomes after stapedotomy, and has the same negative effect on ABG development as any other surgical failure, while the revision could be more challenging in these cases - The use of the most atraumatic surgical technique and preservation of intact intratympanic mucosa is a key factor during middle ear surgery.