Acute appendicitis (AA) is one of the most performed surgical procedures in emergency departments. AA has a hazard rate of 1.17 to 1.9 per 1,000 habitants/year, and a lifetime risk of 8.6% for men and 6.7% for women. The treatment of acute appendicitis is traditionally emergency appendectomy.

Open appendectomy was first described by George Thomas Martin in 1887 and then by Charles McBurney in 1889. The first laparoscopic appendectomy (LA) was not performed until 1983 by Kurt Semm [1].

The first time an appendectomy was performed as outpatient surgery was in 1994 [2]. However, an increase in complications and hospital readmissions was observed. Since then, many systematic reviews have been published [3,4]. Data reported in 17 studies (mainly retrospective) suggested that outpatient appendectomy might be feasible. Several observational studies have shown that outpatient surgery is not associated with increased readmissions, increased morbidity rates, or reoperation [2,4-6].

In 2019 de Wijkerslooth [4] published a systemic review and meta-analysis of comparative studies. However, significant clinical heterogeneity was observed and therefore no recommendations could be given. Currently available data [4,7-9] suggest that in selected patients with uncomplicated AA, patients can be managed via an outpatient route, but there is no good-quality evidence for this.

In November 2022, the first RCTs have been published by Elvira Lopez et al. [10], in Tarragona, Spain.

AA is one of the most common general surgical emergencies worldwide. The reported life-time risk of appendicitis in the United States is 8.6% in men and 6.7% in women, with an annual incidence of 9.38 per 100.000 persons. The most common age range is between 25 and 35 [7].

Classically, a scale of degrees of appendicitis had been proposed: flemmonose, gangrenous and perforated. The postoperative average evolution for each degree of inflammation ranges from 1 to 7 days. The concern lies in the postoperative complications derived from patients with gangrenous or perforated appendicitis. Hence the importance of being able to establish the degree of appendicitis before the operation to predict the complications that may occur. However, current scientific evidence has not been conclusive regarding the predictors of acute uncomplicated appendicitis.

The severity of clinical classification of AA is based on preoperative assessment. During the WSES in 2015 [11], a group of AA-experts discussed many current aspects ending with a new comprehensive disease grading system. Gomes et al. [12], proposed a new comprehensive grading system of AA. Operative findings and intra-operative grading seem to correlate better than histopathology in terms of morbidity, overall outcomes, and costs. This intraoperative grading can determine the optimal postoperative management according to the grade of the disease and the improvement of the utilization of resources [11].

Different options have been described for the treatment of AA. Some authors have proposed a non-surgical treatment [11,13]. However, major complications have been reported in the antibiotic-alone treatment group, and a high recurrence rate (22.6%) during the first year of the appendicitis episode [11,13]. For this reason, the COMA trial concludes that surgery should continue to be the mainstay of treatment for AA [14].

Several systematic reviews of RCTs compared LA with open appendectomy. They reported that LA is often associated with longer operative times and higher operative costs, but leads to less postoperative pain, shorter stay, lower incidence of surgical site infection, earlier return to work and physical activity, and better outcomes, and quality of life scores [11,15]. Thus, in most hospitals in Western countries, LA has become the preferred approach.

Nechay et al. [16] published a modified Enhanced Recovery after Surgery (ERAS) protocol based on the well-known ERAS program for elective (colorectal) surgery [17]. The choice of modified ERAS protocol components was determined by how well they could be adapted to the emergency setting [16,18]. The behind publications showed that the management of outpatient appendectomy [19] was safe and feasible. This evidence was validated for patients with uncomplicated AA [20].

Trejo-Avila demonstrated in 2019 that implementation of ERAS for appendectomy is associated with a significantly shorter LOS, allowing for outpatient management. The authors concluded that outpatient LA is safe and feasible with similar morbidity and readmission rates compared to conventional care [21].

Regarding the definition of outpatient criteria, the definitions used so far for early discharge vary widely. There is no globally accepted definition of ambulatory care or outpatient management. If we review the medical literature on outpatient management, we find that the best definitions are given by Viñoles [22] and Cosse [3], in which a hospital stay of less than 23 hours was defined as the standard for ambulatory surgery. Although these standards do not include emergency procedures. Nevertheless, the laparoscopic appendectomy could be comparable with a laparoscopic cholecystectomy, included in group II of the Davis classification [23].

The first experience of ambulatory care in the management of AA was published in 2015 by Lefrancois [24] as a prospective descriptive study. Multivariate analysis was performed to create a predictive score of same-day discharge. It allowed to select patients eligible for ambulatorization with a success rate of 97%. However, this study did not assess the severity of appendicitis based on the intraoperative findings. This type of care needs to be validated on a largest cohort.

Di Saverio in a 2020 update to the WSES Jerusalem [11] guidelines, and Wijkerslooth in a systematic review, established that outpatient LA for uncomplicated AA is feasible and safe with no difference in morbidity and readmission rates. These results are associated with the potential benefits of earlier recovery after surgery and lower hospital and social costs. However, the quality of the evidence was moderate and the strength of recommendation weak (2B).

Since 2017, four comparative studies have been published in adult patients, using a prospective protocol of a historical control cohort [2,5,24,25]. In addition, two other non-RCT multicenter studies [2,25] and only one systematic review [4] with significant heterogeneity were published.

Finally, in 2022 a randomized clinical trial was published by Elvira Lopez [10]. In this study, 120 patients with uncomplicated acute appendicitis were operated by laparoscopic appendectomy. Once uncomplicated appendicitis was confirmed intraoperatively, the patients were randomized into two groups: hospitalization and outpatient management. The patients in the outpatient group were discharged in less than 23 hours if they met the ALDRETE criteria.

The length of hospital stay (LHS) is similar in all clinical studies with ambulatory. In the ASI trial, LHS was significantly lower in the outpatient group, 8.82h (SD 0.83), while in the hospitalization group it was 45.43h (SD 0.96). In the non-experimental clinical studies, the mean LHS ranged between 3.1h and 9.6h [4,9,27].

In the outpatient management, no increased incidence of complications has been reported. Studies such as those of Lefrancois or Debois have shown that following an ERAS protocol and outpatient management of uncomplicated AA in adult patients is a safe procedure, with low complications and readmission rates ranging from 0% to 4.6% [24,25]. The ASI trial has shown no further complications or readmissions were observed in either group (p=0.320) [10]. The ASI trial published a lower percentage of complications especially Clavien-Dindo 1 (all related to the presence of postoperative abdominal pain) in the outpatient groups than the Hospitalization group [26]. For these remarkable and significant findings, there is no clear clinical or pathophysiological explanation despite having evaluated inflammatory parameters, such as C-reactive protein and leukocyte levels, and surgical findings. It would be interesting to carry out other studies to try to explain these findings.

In terms of costs, AA is associated with a considerable financial burden due to its high incidence and the cost of hospitalization. The effective use of resources by minimizing costs and maintaining quality is the goal of health care. In 2009, the estimated cost of hospitalization for patients with AA was estimated to be $1,900 in the US [7]. Various prospective studies with same-day surgery, such us de Wijkerslooth or Frazee, reported a median reduction in hospital costs ranging from $323 to $4111 per patient [4,9,26]. In the ASI study, health savings were $516.52 per patient [10].

Assessing possible limitations of randomized clinical trials of laparoscopic appendectomies is that the study designs are not blinded. This fact may be considered a limitation, but the nature of the interventions performed made it clear to patients and physicians which group was assigned treatment.

Another possible limitation of the use of outpatient management of acute appendicitis is the change in the mentality of both patients and surgeons. It is a difficult habit change. Classically, an admission of at least 1 day has been performed. The most difficult thing is to convince patients and surgeons that this management is possible and feasible. An outpatient management that does not lead to further risks, complications, or readmissions. It is a global change of mentality about the management of emergency appendectomy, since McBurney performed the first published appendectomy in 1889. During the first stage of the COVID-19 pandemic, the outpatient management allowed a greater availability of hospital beds to care for patients with medical conditions. Thus, outpatient appendectomy allows better optimization of resources. This helped to enable the use of outpatient management, and to demonstrate its usefulness.

All studies agree that outpatient management is safe and feasible [2,4,5,8,9,10,24,28,29]. We can conclude that in our experience it is possible to start an ERAS protocol and an outpatient appendectomy program with an experienced team. Although several studies [2,4,8] had shown, a reduction in LHS in patients selected for outpatient treatment. The ASI trial has shown that ambulatory appendectomy with the ERAS protocol is safe in selected patients, due to the improvement in terms of quality of care, clinical and economic benefits. The following studies should aim to test the outpatient management of complicated appendicitis, and to be able to select predictors of severity.

The emergency outpatient appendectomy with an ERAS protocol is a safe and feasible procedure in selected patients with non-complicated appendectomy. Outpatient management achieves low morbidity, low readmissions, high patient satisfaction and reduced costs. This approach will become the standard of care for patients with uncomplicated AA in the future.

Obtained.

The authors declare that they have no competing interests.

The study was not funded by any grant.