To develop a modified version of Objective Structured Assessment of Technical Skill (OSATS) rating scale for evaluation of surgical skills specific to caesarean and to assess its relevance in documenting the residents’ learning curve during their training. Secondarily, to verify the scale’s stability to caesarean’s level of difficulty and comparing self-assessment to hetero-assessment in order to propose a practical application of this rating scale during residency.

We conducted a multicentre observational prospective study, from May 2018 to November 2018. All residents at that time could participate and fill in the rating scale after caesarean. Senior surgeons had to fill in the same rating scale. We analysed correlation between self-assessments and hetero-assessments and sensitivity to change of the rating scale. Analysis of feature’s relevance was performed by principal component analysis, factor analysis and reliability analysis.

In total, 234 rating scales were completed evaluating 18 residents. Our study demonstrated that our rating scale could be used to evaluate surgical skills of residents during caesarean and distinguish their year of residency (p < 0.001) with a high correlation between self and hetero-assessment (Intraclass Correlation coefficient for global score: 0.78; 95% CI 0.68−0.86). The principal component analysis revealed two dimensions corresponding to the two parts of the rating scale and the factorial analysis allowed us to confirm distribution of features according to these two dimensions. Cronbach’s alpha allowed us to highlight the percentage of representation of the scale’s features in relation to all potential theoretical features (0.93, 95% CI 0.82−0.95).

Our rating scale could be used for self-assessment during residency and as a hetero-assessment tool for validating defined stages of the internship.