Table 1.

Framework to which observations are categorized

Risk domain	Influencing factor	Observation (quantity)
Input
Surgical team	Knowledge and experience of individual team member	Experience of every individual team member defined as the estimated number of similar procedures previously performed
Social interaction	Verbal and nonverbal communication	Events concerning verbal miscommunication
	Teamwork	Events concerning teamwork
Technology	Availability and functioning of equipment and instruments	Events concerning the presence or correct positioning of instruments or equipment
		Events concerning the functioning of instruments or equipment
Organization	Staffing and planning	Adequate scheduling
		Adequate staffing
	Availability of recourses	Availability of supplies
		Availability of technological items
Safeguarding system	Compliance of policies adapted for patient safety	Correct execution of the time-out procedure
Environment	Case-irrelevant disturbing factors	Door movements
		Telephone calls
		Pager calls
		Radio use
		Case-irrelevant conversation
Patient characteristics	Condition of the patient	ASA score
		BMI
Complexity of surgery	Difficulty level of the surgery	MIS: type of procedure that can be categorized in RCOG levels
		CS: type of procedure
Output
Performed procedure		Was the procedure performed as intended?
Intraoperative complication		Did intraoperative complications occur?
Postoperative complication		Postoperative complications up to 6 weeks afterward
Blood loss		Amount of blood loss
Procedure time		Total observational and intraoperative procedure time

ASA American society of anesthesiologists; BMI body mass index; MIS minimally invasive surgery; RCOG Royal college of obstetricians and gynecologists; CS conventional surgery