No validated triaging systems to manage emergency surgical patients in non-austere or war environments are reported in the literature [16].

The COVID-19 pandemic showed that implementing an effective surgical triage is crucial in particular in periods of restricted resources in order to protect frail patients and healthcare workers, and guarantee good use of the available resources while maintaining an acceptable quality of care. After the COVID-19 pandemic, the already stretched healthcare systems are facing the issue of unacceptable long elective waiting lists and the risk of another pandemic. During the early stages of the pandemic, the emergency surgeon was in charge of the decision to operate or delay a surgical procedure or treat non-operatively patients on the basis of national and international specific guidelines for COVID and non-COVID patients, often on the ground of non-evidence-based concepts, with high responsibility [17]. Currently, as “normal” daily practice has returned, the organization of emergency surgery must deal with the necessary rescheduling of previously cancelled elective non-time-dependent surgery but also the issue of restricted staff and lack of dedicated emergency theatres, while considering that outcomes in the emergency setting are time-dependent, in particular in critically ill and frail patients whose survival can be affected by unexpected delays.

An effective triaging system should be clear, simple, transparent, fast and related to the decision‐making process taking into account priorities, the patient’s clinical condition (haemodynamic stability or instability), and the severity of disease (diffuse peritonitis with and without shock; localized peritonitis; bowel obstruction with and without bowel ischaemia; soft tissue infections with and without sepsis) according to evidence-based guidelines [18]. Prioritizing emergency operations by using a risk-stratifying system of different classes is the most effective tool to triage multiple urgent conditions with different severity.

To our knowledge, there are no effective and validated triaging and organization systems to manage the access to the emergency theatre able to decrease the time between admission to the ED and surgical management when needed. The ORSA study [3] showed that most hospitals have no dedicated emergency operating theatre; the emergency operating theatre is not always available; elective surgical procedures were postponed or cancelled to make room for emergency surgery during the day; and the operating rooms flow is managed empirically by the anaesthesiologist often on the basis of local, non-validated and non-reproducible triage systems.

It necessarily follows that the emergency pathway must be reorganized to improve patients' safety, guarantee good use of resources, and decrease costs.

Different triage systems have been recently proposed to improve the flow of emergency surgical patients. To our knowledge, the triaging systems that are largely available are the NCEPOD and TACS classifications. The NCEPOD classification includes 4 categories: immediate, urgent, expedited, and elective. Although largely used in the UK, it is quite inaccurate in defining the right timing to perform a surgical procedure according to the class of priority [6].

The TACS classification was designed to have 5 colour-code classes according to an ideal time for surgery.

It was reported that the traffic light colour-coding system could decrease the delay in operative management. The experience of a single hospital after the introduction of a colour-coding system showed that night emergency surgical procedures significantly decreased from 27.4% before to 23.5% (p < 0.001) and red code surgery increased from 45.2 to 62.7% [11].

A prospective study assessed the rate of adherence between the realization of planned surgical urgency and triaging made through the local triage system including 4 classes and based on the surgeon’s perceptions. The study demonstrated that the higher the degree of priority, the greater the chance of the surgery being performed within the required time [12].

A retrospective study in a tertiary hospital which implemented TACS classification in daily routine for 4 surgical specialties with high demand for emergencies demonstrated that the TACS classification significantly improved the timing of surgery in the yellow class and during the night [13].

Moreover, the TACS classification showed more accuracy than NCEPOD in describing a patient’s clinical condition, but the attribution of a patient to a specific class of priority depends on the surgeon’s evaluation which could be questioned by the anaesthesiologist who often regulates the priority of urgent surgical procedures, and surgeons of other specialities, waiting to perform an emergency procedure.

The new TACS classification was conceived to improve clarity in the processes of assigning a patient to a specificity class of severity and reproducibility.

The new TACS provides 6 colour-coding classes correlated with a defined optimal timing of surgery, defined scenarios, patient’s condition and surgical diseases. The WHITE colour-code class was introduced in the new TACS to reschedule cancelled or postponed surgical procedures that need to be rapidly planned, within the week. Haemodynamic stability after resuscitation remains the main tool to stratify patients for immediate surgery or not in the presence of sepsis/septic shock, in defined scenarios such as diffuse peritonitis with and without shock, localized peritonitis, bowel obstruction with and without bowel ischaemia and soft tissues infection with and without sepsis.

By including well-defined surgical diseases in the different colour-coded classes of priority, validated by an expert multidisciplinary panel, the new TACS improves communication among surgeons and anaesthesiologists and decreases conflicts and wasted time.

The attribution of a patient to one or the other colour-coded class makes immediately evident to the anaesthesiologist and the OR team the severity of the condition and the optimal timing of surgery. However, the implementation of an emergency surgery pathway, and therefore the optimization of the workflow in the emergency theatre, is up to the managers of each trust, bearing in mind that there is no acceptable delay for patients when a prolonged delay might lead to life-threatening conditions and poorer outcomes or more invasive surgical treatment and prolonged hospital stay.

Well-defined clinical pathways and timely and appropriate surgical interventions improve outcomes and decrease healthcare systems costs.

To the best of our knowledge, the new TACS is the only available content-validated triage system through a Delphi consensus of experts.

Further prospective multicentric global study is needed to definitely demonstrate the validity and reproducibility of the new TACS in surgical practice and outcomes in terms of timing of OR access and postoperative morbidity and mortality rate.