This multicenter, prospective observational study (APENERAS) evaluates adherence to the RICA (ERAS Zaragoza 2022) perioperative care pathway in adults undergoing urgent laparoscopic appendectomy for uncomplicated acute appendicitis. The study aims to describe real-world adherence to the pathway across participating hospitals and to explore its association with patient safety and recovery outcomes.

Key outcomes include postoperative complications (including severity), length of hospital stay, and readmissions within 30 days. Patient-reported satisfaction is also assessed using a structured survey. In addition, the study evaluates the feasibility of early discharge/ambulatory management by intention-to-treat, using a standardized checklist of clinical, functional, and social discharge criteria assessed during the first 24 hours after surgery.

No changes to usual clinical care are introduced. Data are collected from routine perioperative management and follow-up.

APENERAS is a prospective, multicenter observational study conducted in adult patients undergoing urgent laparoscopic appendectomy for uncomplicated acute appendicitis. The study assesses real-world adherence to the RICA (ERAS Zaragoza 2022) pathway, a structured set of perioperative recommendations intended to optimize recovery and standardize care in urgent surgery settings.

The primary objective is to quantify overall adherence and adherence by individual components of the pathway. Secondary objectives include evaluating the association between adherence and (1) postoperative safety outcomes (complications and severity classification), (2) efficiency outcomes (length of stay), (3) unplanned healthcare use (readmissions within 30 days), and (4) patient experience (satisfaction survey completed at discharge). In addition, feasibility of early discharge/ambulatory management is assessed by intention-to-treat using a standardized discharge-readiness checklist (clinical stability, pain control with oral analgesia, oral tolerance, mobilization, spontaneous urination, wound status, and social support), evaluated during the first postoperative day.

Candidate profiles for early discharge are also explored using established clinical prediction tools (e.g., Saint-Antoine Score), together with demographic and clinical covariates. Follow-up is performed up to 30 days after surgery to capture postoperative events and readmissions.

This study does not involve any experimental intervention, drug, or device, and does not require changes to standard clinical practice. It is based on systematic data collection from routine care processes and clinical records in each participating center.

Inclusion Criteria:

• Age ≥ 18 and ≤ 75 years.
• Immunocompetent patients.
• ASA physical status I-III.
• Preoperative diagnosis of uncomplicated acute appendicitis (based on clinical assessment, laboratory tests, and imaging such as ultrasound and/or CT according to availability).
• Indication for urgent appendectomy for uncomplicated appendicitis.
• Laparoscopic approach.
• Expected operative time < 90 minutes.
• Cooperative patient able to understand and follow instructions.
• Voluntary participation and written informed consent.
• Adequate social/family support (availability of a responsible adult for transport home and support during the first postoperative days).
• Travel time from home to hospital < 1 hour and access to transportation.
• Acceptable home environment for recovery (telephone access and basic habitability/hygiene).

Exclusion Criteria:

• ASA physical status IV.
• Age < 18 years or > 75 years.
• BMI > 35 kg/m² with significant respiratory or cardiovascular complications.
• Ischemic heart disease class IV or acute myocardial infarction within the last 6 months.
• Congestive heart failure NYHA class III-IV.
• Sleep apnea or severe COPD, or need for home oxygen therapy.
• Poorly controlled diabetes mellitus.
• Severe psychiatric disorders, drug addiction, or severe alcoholism.
• History of major anesthesia-related complications or malignant hyperthermia.
• Epilepsy.
• Pregnancy.
• Use of anticoagulants, MAO inhibitors, systemic corticosteroids, or immunosuppressive drugs.
• Complicated appendicitis (gangrenous or perforated appendicitis, abscess, diffuse peritonitis).
• Severe sepsis.
• Primary open appendectomy or conversion to open surgery.
• Positive SARS-CoV-2 PCR or symptoms compatible with COVID-19.

Adults aged 18-75 years undergoing urgent laparoscopic appendectomy for uncomplicated acute appendicitis in participating hospitals. The study evaluates adherence to the RICA (ERAS Zaragoza 2022) pathway in routine clinical practice, early discharge feasibility (8, 12, and 24 hours after surgery), and safety outcomes (complications, readmissions, reinterventions, and mortality) up to 30 days after surgery. No experimental intervention is introduced.

De-identified individual participant data (IPD) underlying the results reported in publications will be shared. The shared dataset will contain coded study IDs and will exclude direct identifiers (e.g., name, medical record number, address). Variables will be minimized/modified as needed to reduce re-identification risk in accordance with GDPR and institutional policies.

Available beginning 12 months after publication of the primary results and for 5 years thereafter.

Access will be granted to researchers with a clear research question and an appropriate analysis plan, subject to review and approval by the study team and compliance with GDPR and applicable institutional policies. Data will be provided in de-identified form after completion of a data sharing agreement. Requests should be submitted by email to: estudioapeneras@gmail.com