A 55-year-old male undergoes an emergency laparoscopic cholecystectomy for acute calculous cholecystitis. During the procedure, significant hemorrhage is encountered, necessitating conversion to an open laparotomy. The surgical field becomes challenging due to extensive bleeding and adhesions. As the bleeding is controlled and the team prepares for closure, the circulating nurse announces that the sponge count is incorrect, with one laparotomy sponge unaccounted for. The lead surgeon performs a brief manual exploration of the surgical cavity, states that no sponge is palpable, and proceeds with closure, citing the patient's hemodynamic instability and prolonged operative time. Two days post-operatively, the patient develops increasing abdominal pain, fever, and a palpable tender mass in the right upper quadrant. A CT scan confirms the presence of a retained laparotomy sponge. Subsequent surgical removal is successful, but the patient experiences a protracted recovery with wound infection. From a medical-legal perspective in Canada, what is the most significant aspect contributing to the retained surgical item in this scenario?