The Emergency Department (ED) has been facing challenges for years as the demand for its services grows faster than it can accommodate. This condition, exacerbated by congestion, forces patients out of the ED. Not only does this put patients at risk of losing contact with care systems, but it can also be used as a quality measure for performance evaluations due to the phenomenon known as “left without being seen” (LWBS). The LWBS rate for 2021 at ASL Naples 3 South’s Emergency Department in Italy was investigated in this study. Hence, the study incorporated statistical analysis and firth logistic regression to look at the LWBS phenomenon from the Naples emergency department, which is part of the ASL Naples 3 South (Italy). The results show that non-critical patients who visit the ED in the evening have a higher chance of leaving the institution. In particular, patients who leave the emergency department (ED) typically have a younger average age, a White or Green code, and they arrive between 12:00 and 24:00 independently. The average ED-LOS wait time for both groups, when considering thinking, is 180 min. The aim is to ascertain if the identified and readily available risk factors function as indicators of ED exit behavior. The entire activity for the year 2021 was elaborated at the Emergency Department of the ASL Napoli 3 Sud (Italy), providing a knowledge base from which to combat the LWBS phenomenon through Lean methodology.