| Absence | Circulating nurse out of theatre when she is needed to get clipper for cystic duct/artery |
| Coordination/communication problem | Surgeon asks nurse ×3 for vascular sling before receiving it |
| Distraction | Mobile phone rings loudly during case |
| Equipment/workspace management problem | Diathermy unplugged when required |
| Equipment operation problem | Transducer not zeroed giving false readings |
| Equipment problem | Sutures break |
| Expertise/skill problem | Consultant surgeon captures error made by trainee surgeon |
| External resource problem | Piece of equipment is missing from standard set |
| Patient-sourced procedural difficulties | Difficult anatomy causing operative difficulties |
| Planning problem | Difficult intubation anticipated but not planned for |
| Procedure-related error | Arterial clamp time not recorded |
| Non-operative psychomotor error | Retractor is dropped |
| Resource management problem | Surgeon leaves assistant to close without confirming ability to do so |
| Safety consciousness problem | Anaesthetist not wearing face mask in carotid endarterectomy, despite being protocol during vascular cases |
| Vigilance/awareness problem | Anaesthetist fails to note significant drop in arterial pressure |