When does oasis cause de novo pelvic floor dysfunction? role of the surgeon's skills

Introduction and hypothesis: Minorly skilled gynecologists are less likely to repair obstetric anal sphincter injuries (OASIS), and this can lead to higher rate of de novo onset of pelvic floor dysfunction (PFD). The aim of this study was to understand the impact of surgeon skills in OASIS repair on de novo incidence of PFDs. Methods: An observational prospective cohort study performed between January 2019 and December 2020. We included 116 women with OASIS. At 6-weeks from delivery, women were divided into two groups in relation to the onset of PFDs. Characteristics were compared; categorical and continuous variables were assessed with chi-squared test and the Mann–Whitney rank-sum test respectively. Factors involved in PFDs development were analysed with explorative univariate analysis; significant (p<0.05) or approaching significance (p≤0.10) variables were included in multivariable analysis. Results: Seventy-six women (76/116; 65.5%) reported at least one PFD symptom and anal incontinence was the most prevalent (44.73%; 34/76). OASIS management by a skilled gynaecologist resulted protective for PFDs [aOR 0.33 (0.13-0.61)]. Skilled surgeon reported fewer PFDs than less skilled surgeon (4% vs 82.4%; p<0.0001). Operative delivery was more performed (32.5% vs 15.8%; p= 0.03) and severe OASIS resulted more prevalent (60% vs 17.1%; p<0.0001) among women without PDFs, even if these didn’t affect the incidence of de novo PFDs [aOR 1.03 (0.23-1.45) and 0.83 (0.13-1.45), respectively]. Conclusions: Surgeons skilled in OASIS repair resulted the only protective factor for incidence of de novo PFDs in women with OASIS at 6 weeks of follow up. Improvement of training in OASIS repair is necessary.