Our study examines the impact of PoCUS/CT on ED-LOS and time to surgical consultation in patients with mild AC. Patients in the PoCUS-first and CT-first groups showed similar overall ED-LOS and time to surgical consultation. Notably, PoCUS performed within 60 min in the PoCUS-first group significantly reduced ED-LOS and facilitated earlier surgical consultation, as well as CT performed within 120 min in the CT-first group. Our findings suggest that the timely use of PoCUS and CT is associated with improved clinical outcomes, including a reduction in ED-LOS and expedited time to surgical consultation. This underscores the importance of performing PoCUS or CT at optimal times to enhance patient flow.

Modern EDs not only deliver urgent care for life-threatening conditions but also provide diagnostic assessments for a wide range of diseases [16]. Consequently, ED-LOS has significantly increased, leading to crowding and potential complications [17]. While the optimal time target for patients with AC remains uncertain, ED-LOS of less than 36 h has been frequently reported [10, 18, 19]. Furthermore, previous studies have shown that the time to surgical consultation in ED patients typically ranges from 3 to 12 h [10, 19]. In our study, the overall time to surgical consultation in the PoCUS group and the CT group fell within these reported benchmarks although the ED-LOS was higher.

While cholecystectomy remains the gold-standard treatment for AC, non-operative management has emerged as a proposed alternative in recent years [20, 21]. Our findings indicate that patients undergoing emergency cholecystectomy had a shorter ED-LOS, with a median time of approximately 15 h when following a streamlined workflow from ED presentation to operative unit transfer and subsequent ward admission. Reported median times from presentation to surgery in the literature range from 10 to 34 h [10,11,12], and our results align with this range. Notably, the proportion of patients undergoing emergency cholecystectomy (18%) was comparable between the CT-first and PoCUS-first groups, resulting in similar overall ED-LOS for both cohorts. The majority of patients in this study received non-operative management, which likely contributed to the longer ED-LOS observed compared to the durations reported in the literature. Furthermore, ED admissions, which accounted for less than 20% of total hospital admissions, were associated with a prolonged ED-LOS.

PoCUS is considered a “21st-century stethoscope” to evaluate a broad spectrum of illnesses and possibly change the management in emergency settings [22, 23]. PoCUS offers several advantages, including real-time imaging, non-invasiveness, and the absence of ionizing radiation. Unlike CT, PoCUS does not require waiting for renal function data, allowing for quicker diagnostic decisions. While previous studies primarily assessed the diagnostic accuracy of PoCUS for AC by comparing it with CT scans, operative notes, or pathological reports [24,25,26], few have explored its integration into clinical workflows. One notable study found that PoCUS performed by surgeons had a mean diagnostic time of 2.5 h, significantly shorter than the 11.9 h required for radiologist-performed US [24]. In our study, although the ED-LOS was similar between patients receiving CT within 120 min and those receiving US within 60 min, the diagnosis was made earlier in patients who underwent PoCUS first. This underscores the potential of PoCUS to expedite clinical diagnosis.

There are possible explanations for why PoCUS facilitates management process. PoCUS is performed at the bedside by the treating physician, eliminating the need to wait for radiology department availability or patient transport. The rapid diagnostic capability of PoCUS enables a more efficient clinical pathway, allowing ED physicians to quickly determine the need for collaboration with other specialties, thereby streamlining workflow and enhancing overall efficiency. Scholars have underscored the need to improve inter-clinician communication to enhance ED patient flow and increase patient safety [14, 27]. The real-time findings from PoCUS provide timely information and facilitate quicker and more direct communication and coordination with surgical or radiological teams, enabling faster management process. At our hospital, ED physicians promptly communicated with surgeons after performing PoCUS although formal surgical consultations were generally initiated only after CT confirmation.

Also, physicians who are willing to perform US may be relatively more proactive [28, 29], as this often indicates a tendency to actively seek immediate information to expedite decision-making. Moreover, the value of PoCUS is particularly significant during night shifts when radiology reports are not readily available. In our study, a higher proportion of patients presenting during night shifts underwent PoCUS as the initial diagnostic modality.

The characteristic sonographic findings of AC are thickened gallbladder wall, gallbladder distention, incarcerated gallstone, pericholecystic fluid collection, and sonographic Murphy’s sign [30, 31]. The distribution of sonographic findings was similar between PoCUS performed in under 60 min and over 60 min. The sensitivity observed in the PoCUS group was consistent with values reported in the literature [32, 33]. However, true-negative cases were not included, which prevented the evaluation of other diagnostic performance metrics for PoCUS.

This study had limitations. First, its retrospective design meant that certain clinical details, such as specific symptoms, patient flow, and physicians' discretion in selecting PoCUS or CT, were not documented. However, key symptoms of AC (RUQ pain and fever) were routinely recorded and included in the analysis. Additionally, door-to-physician time was accounted for, serving as a partial proxy for patient presentation time. Second, the data were collected from a single institution with active US training and ready access to US devices. This limits generalizability, and further validation in other emergency settings is necessary. Third, as a tertiary medical center, our hospital's patient population had more severe and complex comorbidities. A higher proportion of patients with malignancies received CT first in our study. Nevertheless, the effect of PoCUS on ED-LOS remained significant after adjusting for covariates, including comorbid conditions. Fourth, there was an imbalance in the number of patients between the PoCUS-first and CT-first groups, which may have introduced selection bias. This discrepancy reflects real-world practice, where ED physicians often have individual preferences for using US or CT during evaluations. Implementing a randomized study design could help eliminate this bias and provide a more accurate assessment of the clinical efficacy of PoCUS and CT. Fifth, no patients with mild AC at our hospital were managed using PoCUS alone. All patients with mild AC were included in the analysis. Sixth, we did not compare PoCUS performed by ED physicians with US conducted by radiologists, as all sonographic examinations for ED patients at our hospital were exclusively performed by ED physicians. Seventh, although ED physicians promptly communicated with surgeons after performing PoCUS, formal surgical consultations were generally initiated only after CT confirmation. This practice may have contributed to the similar time to surgical consultation observed between the PoCUS-first and CT-first groups. Eighth, we excluded patients with grade II and III AC, so our results may not be generalizable to those patient groups. Ninth, we collected data only up to June 2020 due to the onset of the COVID-19 pandemic. During the pandemic, ED visits declined significantly [34], and management processes were likely impacted by factors such as universal precautions, enhanced disinfection protocols, and other pandemic-related changes [35]. Tenth, although the ED-LOS for patients undergoing emergent cholecystectomy fell within the time frames reported in the literature [36], the overall ED-LOS was longer than expected [9]. A substantial percentage of patients received non-operative management, which may explain the extended ED-LOS and limit the generalizability of the findings. Also, our hospital is an academic medical center where ED admissions account for only 18% of total hospital admissions. A shortage of hospital beds significantly impacts patient flow, making the facilitation of ED processes a critical component of our mission to reduce ED crowding. Eleventh, this study did not evaluate whether the PoCUS-first group incurred lower overall medical costs. However, Taiwan's National Health Insurance (NHI) system, a compulsory single-payer social insurance program, provides coverage for approximately 99% of its 23 million residents [37]. Under this system, patients pay 10–30% of their medical expenses, with the remainder covered by the NHI. As a result, assessing medical costs in Taiwan is challenging to generalize for external comparisons. Finally, this study only included patients with CT-confirmed AC, excluding false-positive and true-negative cases. As a result, the diagnostic accuracy of PoCUS beyond sensitivity could not be fully assessed. Additionally, the impact of varying training levels on diagnostic accuracy was not evaluated. However, PoCUS performed by residents was supervised by attending physicians, likely minimizing the influence of training variability on the results.